diff --git a/public/ch1-discover-docker-tp/index.html b/public/ch1-discover-docker-tp/index.html
index f3cf3bd9a6ad5c9dd1237bd53936e353a6516cdd..a1d9981e0d1f3553ad46ca16a561b89c18e7dee8 100644
--- a/public/ch1-discover-docker-tp/index.html
+++ b/public/ch1-discover-docker-tp/index.html
@@ -920,7 +920,7 @@ We use <code>-–network</code> instead of <code>-–link</code> because the lat
 <ul>
 <li>Project: Maven  </li>
 <li>Language: Java 21  </li>
-<li>Spring Boot: 3.4.2</li>
+<li>Spring Boot: 3.4.5</li>
 <li>Packaging: Jar  </li>
 <li>Dependencies: <strong>Spring Web</strong></li>
 </ul>
diff --git a/public/search/search_index.json b/public/search/search_index.json
index eb1a394bf42751781c6c6ead6622f6f34e43fff3..427f119dec40dcd992d200aefc0877dd3650b5d0 100644
--- a/public/search/search_index.json
+++ b/public/search/search_index.json
@@ -1 +1 @@
-{"config":{"indexing":"full","lang":["en"],"min_search_length":3,"prebuild_index":false,"separator":"[\\s\\-]+"},"docs":[{"location":"","text":"Devops in Action - Guide For each step you have a TD to discover the subject and a TP to put it into practice. The TPs follow each other and the goal is to make you start from a local application and get to an application delivered in production and accessible to all. For that we will give you each a server and a Java application. Part 1 - Docker session Docker TDs are available here Docker TPs are available here Docker slides are available here Please read the indications carefully, most of the time what you need is in front of your eyes! \u00a9 Takima 2025","title":"Devops in Action - Guide"},{"location":"#devops-in-action-guide","text":"For each step you have a TD to discover the subject and a TP to put it into practice. The TPs follow each other and the goal is to make you start from a local application and get to an application delivered in production and accessible to all. For that we will give you each a server and a Java application. Part 1 - Docker session Docker TDs are available here Docker TPs are available here Docker slides are available here Please read the indications carefully, most of the time what you need is in front of your eyes! \u00a9 Takima 2025","title":"Devops in Action - Guide"},{"location":"ch1-discover-docker-td/","text":"Discover Docker Check Checkpoint: do a commit and call us to check your results (don\u2019t stay blocked on a checkpoint if we are busy, we can check \u2154 checkpoints at the same time) Question Point to document/report Tip Interesting information Setup Prerequisites There are no specific skills needed for this tutorial beyond a basic comfort with the command line and using a text editor. Prior experience in developing web applications will be helpful but is not required. As you proceed further along the tutorial, we'll make use of https://cloud.docker.com/. Setting up your computer Getting all the tooling setup on your computer can be a daunting task, but getting Docker up and running on your favorite OS has become very easy. The getting started guide on Docker has detailed instructions for setting up Docker on Mac , Linux and Windows If you're using Docker for Windows make sure you have shared your drive. Important note If you're using an older version of Windows or MacOS you may need to use Docker Machine instead. All commands work in either bash or Powershell on Windows Once you are done installing Docker, test your Docker installation by running the following: docker run hello-world Unable to find image 'hello-world:latest' locally latest: Pulling from library/hello-world 03f4658f8b78: Pull complete a3ed95caeb02: Pull complete Digest: sha256:8be990ef2aeb16dbcb9271ddfe2610fa6658d13f6dfb8bc72074cc1ca36966a7 Status: Downloaded newer image for hello-world:latest Hello from Docker. ... This message shows that your installation appears to be working correctly. Running your first container Now that you have everything setup, it's time to get our hands dirty. In this section, you are going to run an Alpine Linux container (a lightweight linux distribution) on your system and get a taste of the docker run command. To get started, let's run the following in our terminal: docker pull alpine Note Depending on how you've installed docker on your system, you might see a permission denied error after running the above command. Try the commands from the Getting Started tutorial to verify your installation . If you're on Linux, you may need to prefix your docker commands with sudo . Alternatively you can create a docker group to get rid of this issue. The pull command fetches the alpine image from the Docker registry and saves it in our system. You can use the docker images command to see a list of all images on your system. docker images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE alpine latest c51f86c28340 4 weeks ago 1 .109 MB hello-world latest 690ed74de00f 5 months ago 960 B 1.1 Docker Run Great! Let's now run a Docker container based on this image. To do that you are going to use the docker run command. docker run alpine ls -l total 48 drwxr-xr-x 2 root root 4096 Mar 2 16:20 bin drwxr-xr-x 5 root root 360 Mar 18 09:47 dev drwxr-xr-x 13 root root 4096 Mar 18 09:47 etc drwxr-xr-x 2 root root 4096 Mar 2 16:20 home drwxr-xr-x 5 root root 4096 Mar 2 16:20 lib ...... ...... What happened? Behind the scenes, a lot of stuff happened. When you call run : 1. The Docker client contacts the Docker daemon. The Docker daemon checks local store if the image (alpine in this case) is available locally, and if not, downloads it from Docker Store. (Since we have issued docker pull alpine before, the download step is not necessary) The Docker daemon creates the container and then runs a command in that container. The Docker daemon streams the output of the command to the Docker client When you run docker run alpine , you provided a command ( ls -l ), so Docker started the command specified and you saw the listing. Let's try something more exciting. docker run alpine echo \"hello from alpine\" hello from alpine OK, that's some actual output. In this case, the Docker client dutifully ran the echo command in our alpine container and then exited it. If you've noticed, all of that happened pretty quickly. Imagine booting up a virtual machine, running a command and then killing it. Now you know why they say containers are fast! Try another command. docker run alpine /bin/sh Wait, nothing happened! Is that a bug? Well, no. These interactive shells will exit after running any scripted commands, unless they are run in an interactive terminal - so for this example to not exit, you need to docker run -it alpine /bin/sh . You are now inside the container shell and you can try out a few commands like ls -l , uname -a and others. Exit out of the container by giving the exit command. Ok, now it's time to see the docker ps command. The docker ps command shows you all containers that are currently running. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES Since no containers are running, you see a blank line. Let's try a more useful variant: docker ps -a docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 36171a5da744 alpine \"/bin/sh\" 5 minutes ago Exited ( 0 ) 2 minutes ago fervent_newton a6a9d46d0b2f alpine \"echo 'hello from alp\" 6 minutes ago Exited ( 0 ) 6 minutes ago lonely_kilby ff0a5c3750b9 alpine \"ls -l\" 8 minutes ago Exited ( 0 ) 8 minutes ago elated_ramanujan c317d0a9e3d2 hello-world \"/hello\" 34 seconds ago Exited ( 0 ) 12 minutes ago stupefied_mcclintock What you see above is a list of all containers that you ran. Notice that the STATUS column shows that these containers exited a few minutes ago. You're probably wondering if there is a way to run more than just one command in a container. Let's try that now: docker run -it alpine /bin/sh / # ls bin dev etc home lib linuxrc media mnt proc root run sbin sys tmp usr var / # uname -a Linux 97916e8cb5dc 4.4.27-moby #1 SMP Wed Oct 26 14:01:48 UTC 2016 x86_64 Linux Running the run command with the -it flags attaches us to an interactive tty in the container. Now you can run as many commands in the container as you want. Take some time to run your favorite commands. Tip run -it is a very useful command to debug at the lowest level a container. That concludes a whirlwind tour of the docker run command which would most likely be the command you'll use most often. It makes sense to spend some time getting comfortable with it. To find out more about run , use docker run --help to see a list of all flags it supports. As you proceed further, we'll see a few more variants of docker run. 1.2 Terminology In the last section, you saw a lot of Docker-specific jargon which might be confusing to some. So before you go further, let's clarify some terminology that is used frequently in the Docker ecosystem. Images - The file system and configuration of our application which are used to create containers. To find out more about a Docker image, run docker inspect alpine . In the demo above, you used the docker pull command to download the alpine image. When you executed the command docker run hello-world , it also did a docker pull behind the scenes to download the hello-world image. Containers - Running instances of Docker images \u2014 containers run the actual applications. A container includes an application and all of its dependencies. It shares the kernel with other containers, and runs as an isolated process in user space on the host OS. You created a container using docker run which you did using the alpine image that you downloaded. A list of running containers can be seen using the docker ps command. Docker daemon - The background service running on the host that manages building, running and distributing Docker containers. Docker client - The command line tool that allows the user to interact with the Docker daemon. Docker Store - A registry of Docker images, where you can find trusted and enterprise ready containers, plugins, and Docker editions. You'll be using this later in this tutorial. 2.0 Webapps with Docker Great! So you have now looked at docker run , played with a Docker container and also got the hang of some terminology. Armed with all this knowledge, you are now ready to get to the real stuff \u2014 deploying web applications with Docker. 2.1 Run a static website in a container Note Code for this section is in this repo in the static-site directory Let's start by taking baby-steps. First, we'll use Docker to run a static website in a container. The website is based on an existing image. We'll pull a Docker image from Docker Store, run the container, and see how easy it is to set up a web server. The image that you are going to use is a single-page website that was already created for this demo and is available on the Docker Store as dockersamples/static-site . You can download and run the image directly in one go using docker run as follows. docker run -d dockersamples/static-site Note The current version of this image doesn't run without the -d flag. The -d flag enables detached mode, which detaches the running container from the terminal/shell and returns your prompt after the container starts. We are debugging the problem with this image but for now, use -d even for this first example. Tip -d is a very useful option. So, what happens when you run this command? Since the image doesn't exist on your Docker host, the Docker daemon first fetches it from the registry and then runs it as a container. Now that the server is running, do you see the website? What port is it running on? And more importantly, how do you access the container directly from our host machine? Actually, you probably won't be able to answer any of these questions yet! \u263a In this case, the client didn't tell the Docker Engine to publish any of the ports, so you need to re-run the docker run command to add this instruction. Let's re-run the command with some new flags to publish ports and pass your name to the container to customize the message displayed. We'll use the -d option again to run the container in detached mode. First, stop the container that you have just launched. In order to do this, we need the container ID. Since we ran the container in detached mode, we don't have to launch another terminal to do this. Run docker ps to view the running containers. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES a7a0e504ca3e dockersamples/static-site \"/bin/sh -c 'cd /usr/\" 28 seconds ago Up 26 seconds 80 /tcp, 443 /tcp stupefied_mahavira Check out the CONTAINER ID column. You will need to use this CONTAINER ID value, a long sequence of characters, to identify the container you want to stop, and then to remove it. The example below provides the CONTAINER ID on our system; you should use the value that you see in your terminal. docker stop a7a0e504ca3e docker rm a7a0e504ca3e Note A cool feature is that you do not need to specify the entire CONTAINER ID . You can just specify a few starting characters and if it is unique among all the containers that you have launched, the Docker client will intelligently pick it up. Now, let's launch a container in detached mode as shown below: docker run --name static-site -e AUTHOR = \"Enter Your Name Here\" -d -P dockersamples/static-site e61d12292d69556eabe2a44c16cbd54486b2527e2ce4f95438e504afb7b02810 In the above command: -d will create a container with the process detached from our terminal -P will publish all the exposed container ports to random ports on the Docker host -e is how you pass environment variables to the container. --name allows you to specify a container name AUTHOR is the environment variable name and Your Name is the value that you can pass. Now you can see the ports by running the docker port command. docker port static-site 443 /tcp -> 0 .0.0.0:32772 80 /tcp -> 0 .0.0.0:32773 You can open your freshly created website on http://localhost:[YOUR_PORT_FOR 80/tcp] . For our example this is http://localhost:32773 . You can now open http://localhost:[YOUR_PORT_FOR 80/tcp] to see your site live! For our example, this is: http://192.168.99.100:32773 . You can also run a second webserver at the same time, specifying a custom host port mapping to the container's webserver. docker run --name static-site-2 -e AUTHOR = \"Enter Your Name Here\" -d -p 8888 :80 dockersamples/static-site To deploy this on a real server you would just need to install Docker, and run the above docker command (as in this case you can see the AUTHOR is Docker which we passed as an environment variable). Now that you've seen how to run a webserver inside a Docker container, how do you create your own Docker image? This is the question we'll explore in the next section. But first, let's stop and remove the containers since you won't be using them anymore. docker stop static-site docker rm static-site Let's use a shortcut to remove the second site: docker rm -f static-site-2 Tip rm -f is a very useful option Run docker ps to make sure the containers are gone. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 2.2 Docker Images In this section, let's dive deeper into what Docker images are. You will build your own image, use that image to run an application locally, and finally, push some of your own images to Docker Cloud. Docker images are the basis of containers. In the previous example, you pulled the dockersamples/static-site image from the. registry and asked the Docker client to run a container based on that image. To see the list of images that are available locally on your system, run the docker images command. docker images REPOSITORY TAG IMAGE ID CREATED SIZE dockersamples/static-site latest 92a386b6e686 2 hours ago 190 .5 MB nginx latest af4b3d7d5401 3 hours ago 190 .5 MB python 2 .7 1c32174fd534 14 hours ago 676 .8 MB postgres 9 .4 88d845ac7a88 14 hours ago 263 .6 MB containous/traefik latest 27b4e0c6b2fd 4 days ago 20 .75 MB node 0 .10 42426a5cba5f 6 days ago 633 .7 MB redis latest 4f5f397d4b7c 7 days ago 177 .5 MB mongo latest 467eb21035a8 7 days ago 309 .7 MB alpine 3 .3 70c557e50ed6 8 days ago 4 .794 MB java 7 21f6ce84e43c 8 days ago 587 .7 MB Above is a list of images that I've pulled from the registry and those I've created myself (we'll shortly see how). You will have a different list of images on your machine. The TAG refers to a particular snapshot of the image and the ID is the corresponding unique identifier for that image. For simplicity, you can think of an image akin to a git repository - images can be committed with changes and have multiple. versions. When you do not provide a specific version number, the client defaults to latest. For example you could pull a specific version of ubuntu image as follows: docker pull ubuntu:12.04 If you do not specify the version number of the image then, as mentioned, the Docker client will default to a version named latest . So for example, the docker pull command given below will pull an image named ubuntu:latest : docker pull ubuntu To get a new Docker image you can either get it from a registry (such as the Docker Store) or create your own. There are hundreds of thousands of images available on Docker Store . You can also search for images directly from the command line using docker search . An important distinction with regard to images is between base images and child images . Base images are images that have no parent images, usually images with an OS like ubuntu, alpine or debian. Child images are images that build on base images and add additional functionality. Another key concept is the idea of official images and user images. (Both of which can be base images or child images.) Official images are Docker sanctioned images. Docker, Inc. sponsors a dedicated team that is responsible for reviewing and publishing all Official Repositories content. This team works in collaboration with upstream software maintainers, security experts, and the broader Docker community. These are not prefixed by an organization or user name. In the list of images above, the python , node , alpine and nginx images are official (base) images. To find out more about them, check out the Official Images Documentation . User images are images created and shared by users like you. They build on base images and add additional functionality. Typically these are formatted as user/image-name . The user value in the image name is your Docker Store user or organization name. 2.3 Create your first image Now that you have a better understanding of images, it's time to create your own. Our main objective here is to create an image that sandboxes a small Flask application. The goal of this exercise is to create a Docker image which will run a Flask app. We'll do this by first pulling together the components for a random cat picture generator built with Python Flask, then dockerizing it by writing a Dockerfile . Finally, we'll build the image, and then run it. 2.3.1 Create a Python Flask app that displays random cat pix. For the purposes of this workshop, we've created a fun little Python Flask app that displays a random cat .gif every time it is loaded - because, you know, who doesn't like cats? Start by creating a directory called flask-app where we'll create the following files: app.py requirements.txt templates/index.html Dockerfile Make sure to cd flask-app before you start creating the files, because you don't want to start adding a whole bunch of other random files to your image. app.py Create the app.py with the following content: from flask import Flask , render_template import random app = Flask ( __name__ ) # list of cat images images = [ \"https://c.tenor.com/GTcT7HODLRgAAAAM/smiling-cat-creepy-cat.gif\" , \"https://media0.giphy.com/media/10dU7AN7xsi1I4/giphy.webp?cid=ecf05e47gk63rd81vzlot57qmebr7drtgf6a3khmzvjsdtu7&rid=giphy.webp&ct=g\" , \"https://media0.giphy.com/media/S6VGjvmFRu5Qk/giphy.webp?cid=ecf05e478yofpawrhffnnvb3sgjkos96vyfo5mtqhds35as6&rid=giphy.webp&ct=g\" , \"https://media3.giphy.com/media/JIX9t2j0ZTN9S/200w.webp?cid=ecf05e47gk63rd81vzlot57qmebr7drtgf6a3khmzvjsdtu7&rid=200w.webp&ct=g\" ] @app . route ( '/' ) def index (): url = random . choice ( images ) return render_template ( 'index.html' , url = url ) if __name__ == \"__main__\" : app . run ( host = \"0.0.0.0\" ) requirements.txt In order to install the Python modules required for our app, we need to create a file called requirements.txt and add the following line to that file: Flask==3.1.0 templates/index.html Create a directory called templates and create an index.html file in that directory with the following content in it: < html > < head > < style type = \"text/css\" > body { background : black ; color : white ; } div . container { max-width : 500 px ; margin : 100 px auto ; border : 20 px solid white ; padding : 10 px ; text-align : center ; } h4 { text-transform : uppercase ; } </ style > </ head > < body > < div class = \"container\" > < h4 > Cat Gif of the day </ h4 > < img src = \"{{url}}\" /> < p >< small > Courtesy: < a href = \"http://www.buzzfeed.com/copyranter/the-best-cat-gif-post-in-the-history-of-cat-gifs\" > Buzzfeed </ a ></ small ></ p > </ div > </ body > </ html > 2.3.2 Write a Dockerfile We want to create a Docker image with this web app. As mentioned above, all user images are based on a base image. Since our application is written in Python, we will build our own Python image based on Alpine . We'll do that using a Dockerfile. A Dockerfile is a text file that contains a list of commands that the Docker daemon calls while creating an image. The Dockerfile contains all the information that Docker needs to know to run the app \u2014 a base Docker image to run from, location of your project code, any dependencies it has, and what commands to run at start-up. It is a simple way to automate the image creation process. The best part is that the commands you write in a Dockerfile are almost identical to their equivalent Linux commands. This means you don't really have to learn new syntax to create your own Dockerfiles. 1 - Create a file called Dockerfile, and add content to it as described below. We'll start by specifying our base image, using the FROM keyword. We are using alpine:3.21.0, a lightweight Linux distribution that helps keep our container small and efficient: FROM alpine:3.21.0 2 - Next, we need to install Python 3, pip, and other system dependencies required for our application. The apk add command is used to install packages in Alpine Linux. We use --no-cache to prevent unnecessary image bloat. Add the following RUN command: RUN apk add --no-cache build-base libffi-dev openssl-dev py3-pip python3 3 - Now, we set the working directory inside the container. This ensures that all subsequent commands run within this directory: WORKDIR /usr/src/app 4 - To create an isolated Python environment, we set up a virtual environment inside our container. This helps prevent conflicts between system-wide and project-specific dependencies: RUN python3 -m venv venv 5 - To ensure that all commands within the container use the virtual environment by default, we modify the PATH environment variable: ENV PATH = \"/usr/src/app/venv/bin: $PATH \" 6 - Next, we copy the application's dependencies file (requirements.txt) into the container and install the necessary Python packages. We also upgrade pip to the latest version to ensure compatibility: COPY requirements.txt ./ RUN pip install --no-cache-dir --upgrade pip && pip install --no-cache-dir -r requirements.txt 7 - Copy the files you have created earlier into our image by using COPY command. COPY app.py ./ COPY templates/index.html ./templates/ 8 - Since our Flask application runs on port 5000, we specify that this port should be exposed. This does not automatically publish the port but serves as documentation and can be used by orchestration tools: EXPOSE 5000 9 - The last step is the command for running the application which is simply - python ./app.py . Use the CMD command to do that: CMD [ \"python\" , \"/usr/src/app/app.py\" ] The primary purpose of CMD is to tell the container which command it should run by default when it is started. 10 - Verify your Dockerfile. Our Dockerfile is now ready. This is how it looks: # our base image FROM alpine:3.21.0 # Install Python 3, pip, and system dependencies RUN apk add --no-cache build-base libffi-dev openssl-dev py3-pip python3 # Set the working directory WORKDIR /usr/src/app # Create and activate a virtual environment RUN python3 -m venv venv # Use the virtual environment for all commands ENV PATH = \"/usr/src/app/venv/bin: $PATH \" # Copy and install dependencies COPY requirements.txt ./ RUN pip install --no-cache-dir --upgrade pip && pip install --no-cache-dir -r requirements.txt # Copy application files COPY app.py ./ COPY templates/index.html ./templates/ # Expose the application port EXPOSE 5000 # Run the application inside the virtual environment CMD [ \"python\" , \"/usr/src/app/app.py\" ] 2.3.3 Build the image Now that you have your Dockerfile , you can build your image. The docker build command does the heavy-lifting of creating a docker image from a Dockerfile . When you run the docker build command given below, make sure to replace <YOUR_USERNAME> with your username. This username should be the same one you created when registering on Docker Cloud . If you haven't done that yet, please go ahead and create an account. The docker build command is quite simple - it takes an optional tag name with the -t flag, and the location of the directory containing the Dockerfile - the . indicates the current directory: docker build -t <YOUR_USERNAME>/myfirstapp . If you don't have the alpine:3.21.0 image, the client will first pull the image and then create your image. Therefore, your output on running the command will look different from mine. If everything went well, your image should be ready! Run docker images and see if your image ( <YOUR_USERNAME>/myfirstapp ) shows. 2.3.4 Run your image The next step in this section is to run the image and see if it actually works. docker run -p 8888 :5000 --name myfirstapp YOUR_USERNAME/myfirstapp * Serving Flask app 'app' * Debug mode: off WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead. * Running on all addresses ( 0 .0.0.0 ) * Running on http://127.0.0.1:5000 * Running on http://172.17.0.2:5000 Press CTRL+C to quit Head over to http://localhost:8888 and your app should be live. Note If you are using Docker Machine, you may need to open up another terminal and determine the container ip address using docker-machine ip default . Hit the Refresh button in the web browser to see a few more cat images. Check Show us your running flask-app ! 2.3.4 Dockerfile commands summary Here's a quick summary of the few basic commands we used in our Dockerfile. FROM starts the Dockerfile. It is a requirement that the Dockerfile must start with the FROM command. Images are created in layers, which means you can use another image as the base image for your own. The FROM command defines your base layer. As arguments, it takes the name of the image. Optionally, you can add the Docker Cloud username of the maintainer and image version, in the format username/imagename:version . RUN is used to build up the Image you're creating. For each RUN command, Docker will run the command then create a new layer of the image. This way you can roll back your image to previous states easily. The syntax for a RUN instruction is to place the full text of the shell command after the RUN (e.g., RUN mkdir /user/local/foo ). This will automatically run in a /bin/sh shell. You can define a different shell like this: RUN /bin/bash -c 'mkdir /user/local/foo ' COPY copies local files into the container. CMD defines the commands that will run on the Image at start-up. Unlike a RUN , this does not create a new layer for the Image, but simply runs the command. There can only be one CMD per a Dockerfile/Image. If you need to run multiple commands, the best way to do that is to have the CMD run a script. CMD requires that you tell it where to run the command, unlike RUN . So example CMD commands would be: CMD [ \"python\" , \"./app.py\" ] CMD [ \"/bin/bash\" , \"echo\" , \"Hello World\" ] EXPOSE creates a hint for users of an image which ports provide services. It is included in the information which can be retrieved via docker inspect <container-id> . Note The EXPOSE command does not actually make any ports accessible to the host! Instead, this requires publishing ports by means of the -p flag when using docker run . Note If you want to learn more about Dockerfiles, check out Best practices for writing Dockerfiles . (source: https://github.com/docker/labs/tree/master/beginner ) Now that you know how to run docker container and create Dockerfiles let\u2019s move on to the practical part.","title":"TD part 01 - Docker"},{"location":"ch1-discover-docker-td/#discover-docker","text":"Check Checkpoint: do a commit and call us to check your results (don\u2019t stay blocked on a checkpoint if we are busy, we can check \u2154 checkpoints at the same time) Question Point to document/report Tip Interesting information","title":"Discover Docker"},{"location":"ch1-discover-docker-td/#setup","text":"","title":"Setup"},{"location":"ch1-discover-docker-td/#prerequisites","text":"There are no specific skills needed for this tutorial beyond a basic comfort with the command line and using a text editor. Prior experience in developing web applications will be helpful but is not required. As you proceed further along the tutorial, we'll make use of https://cloud.docker.com/.","title":"Prerequisites"},{"location":"ch1-discover-docker-td/#setting-up-your-computer","text":"Getting all the tooling setup on your computer can be a daunting task, but getting Docker up and running on your favorite OS has become very easy. The getting started guide on Docker has detailed instructions for setting up Docker on Mac , Linux and Windows If you're using Docker for Windows make sure you have shared your drive. Important note If you're using an older version of Windows or MacOS you may need to use Docker Machine instead. All commands work in either bash or Powershell on Windows Once you are done installing Docker, test your Docker installation by running the following: docker run hello-world Unable to find image 'hello-world:latest' locally latest: Pulling from library/hello-world 03f4658f8b78: Pull complete a3ed95caeb02: Pull complete Digest: sha256:8be990ef2aeb16dbcb9271ddfe2610fa6658d13f6dfb8bc72074cc1ca36966a7 Status: Downloaded newer image for hello-world:latest Hello from Docker. ... This message shows that your installation appears to be working correctly.","title":"Setting up your computer"},{"location":"ch1-discover-docker-td/#running-your-first-container","text":"Now that you have everything setup, it's time to get our hands dirty. In this section, you are going to run an Alpine Linux container (a lightweight linux distribution) on your system and get a taste of the docker run command. To get started, let's run the following in our terminal: docker pull alpine Note Depending on how you've installed docker on your system, you might see a permission denied error after running the above command. Try the commands from the Getting Started tutorial to verify your installation . If you're on Linux, you may need to prefix your docker commands with sudo . Alternatively you can create a docker group to get rid of this issue. The pull command fetches the alpine image from the Docker registry and saves it in our system. You can use the docker images command to see a list of all images on your system. docker images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE alpine latest c51f86c28340 4 weeks ago 1 .109 MB hello-world latest 690ed74de00f 5 months ago 960 B","title":"Running your first container"},{"location":"ch1-discover-docker-td/#11-docker-run","text":"Great! Let's now run a Docker container based on this image. To do that you are going to use the docker run command. docker run alpine ls -l total 48 drwxr-xr-x 2 root root 4096 Mar 2 16:20 bin drwxr-xr-x 5 root root 360 Mar 18 09:47 dev drwxr-xr-x 13 root root 4096 Mar 18 09:47 etc drwxr-xr-x 2 root root 4096 Mar 2 16:20 home drwxr-xr-x 5 root root 4096 Mar 2 16:20 lib ...... ...... What happened? Behind the scenes, a lot of stuff happened. When you call run : 1. The Docker client contacts the Docker daemon. The Docker daemon checks local store if the image (alpine in this case) is available locally, and if not, downloads it from Docker Store. (Since we have issued docker pull alpine before, the download step is not necessary) The Docker daemon creates the container and then runs a command in that container. The Docker daemon streams the output of the command to the Docker client When you run docker run alpine , you provided a command ( ls -l ), so Docker started the command specified and you saw the listing. Let's try something more exciting. docker run alpine echo \"hello from alpine\" hello from alpine OK, that's some actual output. In this case, the Docker client dutifully ran the echo command in our alpine container and then exited it. If you've noticed, all of that happened pretty quickly. Imagine booting up a virtual machine, running a command and then killing it. Now you know why they say containers are fast! Try another command. docker run alpine /bin/sh Wait, nothing happened! Is that a bug? Well, no. These interactive shells will exit after running any scripted commands, unless they are run in an interactive terminal - so for this example to not exit, you need to docker run -it alpine /bin/sh . You are now inside the container shell and you can try out a few commands like ls -l , uname -a and others. Exit out of the container by giving the exit command. Ok, now it's time to see the docker ps command. The docker ps command shows you all containers that are currently running. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES Since no containers are running, you see a blank line. Let's try a more useful variant: docker ps -a docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 36171a5da744 alpine \"/bin/sh\" 5 minutes ago Exited ( 0 ) 2 minutes ago fervent_newton a6a9d46d0b2f alpine \"echo 'hello from alp\" 6 minutes ago Exited ( 0 ) 6 minutes ago lonely_kilby ff0a5c3750b9 alpine \"ls -l\" 8 minutes ago Exited ( 0 ) 8 minutes ago elated_ramanujan c317d0a9e3d2 hello-world \"/hello\" 34 seconds ago Exited ( 0 ) 12 minutes ago stupefied_mcclintock What you see above is a list of all containers that you ran. Notice that the STATUS column shows that these containers exited a few minutes ago. You're probably wondering if there is a way to run more than just one command in a container. Let's try that now: docker run -it alpine /bin/sh / # ls bin dev etc home lib linuxrc media mnt proc root run sbin sys tmp usr var / # uname -a Linux 97916e8cb5dc 4.4.27-moby #1 SMP Wed Oct 26 14:01:48 UTC 2016 x86_64 Linux Running the run command with the -it flags attaches us to an interactive tty in the container. Now you can run as many commands in the container as you want. Take some time to run your favorite commands. Tip run -it is a very useful command to debug at the lowest level a container. That concludes a whirlwind tour of the docker run command which would most likely be the command you'll use most often. It makes sense to spend some time getting comfortable with it. To find out more about run , use docker run --help to see a list of all flags it supports. As you proceed further, we'll see a few more variants of docker run.","title":"1.1 Docker Run"},{"location":"ch1-discover-docker-td/#12-terminology","text":"In the last section, you saw a lot of Docker-specific jargon which might be confusing to some. So before you go further, let's clarify some terminology that is used frequently in the Docker ecosystem. Images - The file system and configuration of our application which are used to create containers. To find out more about a Docker image, run docker inspect alpine . In the demo above, you used the docker pull command to download the alpine image. When you executed the command docker run hello-world , it also did a docker pull behind the scenes to download the hello-world image. Containers - Running instances of Docker images \u2014 containers run the actual applications. A container includes an application and all of its dependencies. It shares the kernel with other containers, and runs as an isolated process in user space on the host OS. You created a container using docker run which you did using the alpine image that you downloaded. A list of running containers can be seen using the docker ps command. Docker daemon - The background service running on the host that manages building, running and distributing Docker containers. Docker client - The command line tool that allows the user to interact with the Docker daemon. Docker Store - A registry of Docker images, where you can find trusted and enterprise ready containers, plugins, and Docker editions. You'll be using this later in this tutorial.","title":"1.2 Terminology"},{"location":"ch1-discover-docker-td/#20-webapps-with-docker","text":"Great! So you have now looked at docker run , played with a Docker container and also got the hang of some terminology. Armed with all this knowledge, you are now ready to get to the real stuff \u2014 deploying web applications with Docker.","title":"2.0 Webapps with Docker"},{"location":"ch1-discover-docker-td/#21-run-a-static-website-in-a-container","text":"Note Code for this section is in this repo in the static-site directory Let's start by taking baby-steps. First, we'll use Docker to run a static website in a container. The website is based on an existing image. We'll pull a Docker image from Docker Store, run the container, and see how easy it is to set up a web server. The image that you are going to use is a single-page website that was already created for this demo and is available on the Docker Store as dockersamples/static-site . You can download and run the image directly in one go using docker run as follows. docker run -d dockersamples/static-site Note The current version of this image doesn't run without the -d flag. The -d flag enables detached mode, which detaches the running container from the terminal/shell and returns your prompt after the container starts. We are debugging the problem with this image but for now, use -d even for this first example. Tip -d is a very useful option. So, what happens when you run this command? Since the image doesn't exist on your Docker host, the Docker daemon first fetches it from the registry and then runs it as a container. Now that the server is running, do you see the website? What port is it running on? And more importantly, how do you access the container directly from our host machine? Actually, you probably won't be able to answer any of these questions yet! \u263a In this case, the client didn't tell the Docker Engine to publish any of the ports, so you need to re-run the docker run command to add this instruction. Let's re-run the command with some new flags to publish ports and pass your name to the container to customize the message displayed. We'll use the -d option again to run the container in detached mode. First, stop the container that you have just launched. In order to do this, we need the container ID. Since we ran the container in detached mode, we don't have to launch another terminal to do this. Run docker ps to view the running containers. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES a7a0e504ca3e dockersamples/static-site \"/bin/sh -c 'cd /usr/\" 28 seconds ago Up 26 seconds 80 /tcp, 443 /tcp stupefied_mahavira Check out the CONTAINER ID column. You will need to use this CONTAINER ID value, a long sequence of characters, to identify the container you want to stop, and then to remove it. The example below provides the CONTAINER ID on our system; you should use the value that you see in your terminal. docker stop a7a0e504ca3e docker rm a7a0e504ca3e Note A cool feature is that you do not need to specify the entire CONTAINER ID . You can just specify a few starting characters and if it is unique among all the containers that you have launched, the Docker client will intelligently pick it up. Now, let's launch a container in detached mode as shown below: docker run --name static-site -e AUTHOR = \"Enter Your Name Here\" -d -P dockersamples/static-site e61d12292d69556eabe2a44c16cbd54486b2527e2ce4f95438e504afb7b02810 In the above command: -d will create a container with the process detached from our terminal -P will publish all the exposed container ports to random ports on the Docker host -e is how you pass environment variables to the container. --name allows you to specify a container name AUTHOR is the environment variable name and Your Name is the value that you can pass. Now you can see the ports by running the docker port command. docker port static-site 443 /tcp -> 0 .0.0.0:32772 80 /tcp -> 0 .0.0.0:32773 You can open your freshly created website on http://localhost:[YOUR_PORT_FOR 80/tcp] . For our example this is http://localhost:32773 . You can now open http://localhost:[YOUR_PORT_FOR 80/tcp] to see your site live! For our example, this is: http://192.168.99.100:32773 . You can also run a second webserver at the same time, specifying a custom host port mapping to the container's webserver. docker run --name static-site-2 -e AUTHOR = \"Enter Your Name Here\" -d -p 8888 :80 dockersamples/static-site To deploy this on a real server you would just need to install Docker, and run the above docker command (as in this case you can see the AUTHOR is Docker which we passed as an environment variable). Now that you've seen how to run a webserver inside a Docker container, how do you create your own Docker image? This is the question we'll explore in the next section. But first, let's stop and remove the containers since you won't be using them anymore. docker stop static-site docker rm static-site Let's use a shortcut to remove the second site: docker rm -f static-site-2 Tip rm -f is a very useful option Run docker ps to make sure the containers are gone. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES","title":"2.1 Run a static website in a container"},{"location":"ch1-discover-docker-td/#22-docker-images","text":"In this section, let's dive deeper into what Docker images are. You will build your own image, use that image to run an application locally, and finally, push some of your own images to Docker Cloud. Docker images are the basis of containers. In the previous example, you pulled the dockersamples/static-site image from the. registry and asked the Docker client to run a container based on that image. To see the list of images that are available locally on your system, run the docker images command. docker images REPOSITORY TAG IMAGE ID CREATED SIZE dockersamples/static-site latest 92a386b6e686 2 hours ago 190 .5 MB nginx latest af4b3d7d5401 3 hours ago 190 .5 MB python 2 .7 1c32174fd534 14 hours ago 676 .8 MB postgres 9 .4 88d845ac7a88 14 hours ago 263 .6 MB containous/traefik latest 27b4e0c6b2fd 4 days ago 20 .75 MB node 0 .10 42426a5cba5f 6 days ago 633 .7 MB redis latest 4f5f397d4b7c 7 days ago 177 .5 MB mongo latest 467eb21035a8 7 days ago 309 .7 MB alpine 3 .3 70c557e50ed6 8 days ago 4 .794 MB java 7 21f6ce84e43c 8 days ago 587 .7 MB Above is a list of images that I've pulled from the registry and those I've created myself (we'll shortly see how). You will have a different list of images on your machine. The TAG refers to a particular snapshot of the image and the ID is the corresponding unique identifier for that image. For simplicity, you can think of an image akin to a git repository - images can be committed with changes and have multiple. versions. When you do not provide a specific version number, the client defaults to latest. For example you could pull a specific version of ubuntu image as follows: docker pull ubuntu:12.04 If you do not specify the version number of the image then, as mentioned, the Docker client will default to a version named latest . So for example, the docker pull command given below will pull an image named ubuntu:latest : docker pull ubuntu To get a new Docker image you can either get it from a registry (such as the Docker Store) or create your own. There are hundreds of thousands of images available on Docker Store . You can also search for images directly from the command line using docker search . An important distinction with regard to images is between base images and child images . Base images are images that have no parent images, usually images with an OS like ubuntu, alpine or debian. Child images are images that build on base images and add additional functionality. Another key concept is the idea of official images and user images. (Both of which can be base images or child images.) Official images are Docker sanctioned images. Docker, Inc. sponsors a dedicated team that is responsible for reviewing and publishing all Official Repositories content. This team works in collaboration with upstream software maintainers, security experts, and the broader Docker community. These are not prefixed by an organization or user name. In the list of images above, the python , node , alpine and nginx images are official (base) images. To find out more about them, check out the Official Images Documentation . User images are images created and shared by users like you. They build on base images and add additional functionality. Typically these are formatted as user/image-name . The user value in the image name is your Docker Store user or organization name.","title":"2.2 Docker Images"},{"location":"ch1-discover-docker-td/#23-create-your-first-image","text":"Now that you have a better understanding of images, it's time to create your own. Our main objective here is to create an image that sandboxes a small Flask application. The goal of this exercise is to create a Docker image which will run a Flask app. We'll do this by first pulling together the components for a random cat picture generator built with Python Flask, then dockerizing it by writing a Dockerfile . Finally, we'll build the image, and then run it.","title":"2.3 Create your first image"},{"location":"ch1-discover-docker-td/#231-create-a-python-flask-app-that-displays-random-cat-pix","text":"For the purposes of this workshop, we've created a fun little Python Flask app that displays a random cat .gif every time it is loaded - because, you know, who doesn't like cats? Start by creating a directory called flask-app where we'll create the following files: app.py requirements.txt templates/index.html Dockerfile Make sure to cd flask-app before you start creating the files, because you don't want to start adding a whole bunch of other random files to your image.","title":"2.3.1 Create a Python Flask app that displays random cat pix."},{"location":"ch1-discover-docker-td/#apppy","text":"Create the app.py with the following content: from flask import Flask , render_template import random app = Flask ( __name__ ) # list of cat images images = [ \"https://c.tenor.com/GTcT7HODLRgAAAAM/smiling-cat-creepy-cat.gif\" , \"https://media0.giphy.com/media/10dU7AN7xsi1I4/giphy.webp?cid=ecf05e47gk63rd81vzlot57qmebr7drtgf6a3khmzvjsdtu7&rid=giphy.webp&ct=g\" , \"https://media0.giphy.com/media/S6VGjvmFRu5Qk/giphy.webp?cid=ecf05e478yofpawrhffnnvb3sgjkos96vyfo5mtqhds35as6&rid=giphy.webp&ct=g\" , \"https://media3.giphy.com/media/JIX9t2j0ZTN9S/200w.webp?cid=ecf05e47gk63rd81vzlot57qmebr7drtgf6a3khmzvjsdtu7&rid=200w.webp&ct=g\" ] @app . route ( '/' ) def index (): url = random . choice ( images ) return render_template ( 'index.html' , url = url ) if __name__ == \"__main__\" : app . run ( host = \"0.0.0.0\" )","title":"app.py"},{"location":"ch1-discover-docker-td/#requirementstxt","text":"In order to install the Python modules required for our app, we need to create a file called requirements.txt and add the following line to that file: Flask==3.1.0","title":"requirements.txt"},{"location":"ch1-discover-docker-td/#templatesindexhtml","text":"Create a directory called templates and create an index.html file in that directory with the following content in it: < html > < head > < style type = \"text/css\" > body { background : black ; color : white ; } div . container { max-width : 500 px ; margin : 100 px auto ; border : 20 px solid white ; padding : 10 px ; text-align : center ; } h4 { text-transform : uppercase ; } </ style > </ head > < body > < div class = \"container\" > < h4 > Cat Gif of the day </ h4 > < img src = \"{{url}}\" /> < p >< small > Courtesy: < a href = \"http://www.buzzfeed.com/copyranter/the-best-cat-gif-post-in-the-history-of-cat-gifs\" > Buzzfeed </ a ></ small ></ p > </ div > </ body > </ html >","title":"templates/index.html"},{"location":"ch1-discover-docker-td/#232-write-a-dockerfile","text":"We want to create a Docker image with this web app. As mentioned above, all user images are based on a base image. Since our application is written in Python, we will build our own Python image based on Alpine . We'll do that using a Dockerfile. A Dockerfile is a text file that contains a list of commands that the Docker daemon calls while creating an image. The Dockerfile contains all the information that Docker needs to know to run the app \u2014 a base Docker image to run from, location of your project code, any dependencies it has, and what commands to run at start-up. It is a simple way to automate the image creation process. The best part is that the commands you write in a Dockerfile are almost identical to their equivalent Linux commands. This means you don't really have to learn new syntax to create your own Dockerfiles. 1 - Create a file called Dockerfile, and add content to it as described below. We'll start by specifying our base image, using the FROM keyword. We are using alpine:3.21.0, a lightweight Linux distribution that helps keep our container small and efficient: FROM alpine:3.21.0 2 - Next, we need to install Python 3, pip, and other system dependencies required for our application. The apk add command is used to install packages in Alpine Linux. We use --no-cache to prevent unnecessary image bloat. Add the following RUN command: RUN apk add --no-cache build-base libffi-dev openssl-dev py3-pip python3 3 - Now, we set the working directory inside the container. This ensures that all subsequent commands run within this directory: WORKDIR /usr/src/app 4 - To create an isolated Python environment, we set up a virtual environment inside our container. This helps prevent conflicts between system-wide and project-specific dependencies: RUN python3 -m venv venv 5 - To ensure that all commands within the container use the virtual environment by default, we modify the PATH environment variable: ENV PATH = \"/usr/src/app/venv/bin: $PATH \" 6 - Next, we copy the application's dependencies file (requirements.txt) into the container and install the necessary Python packages. We also upgrade pip to the latest version to ensure compatibility: COPY requirements.txt ./ RUN pip install --no-cache-dir --upgrade pip && pip install --no-cache-dir -r requirements.txt 7 - Copy the files you have created earlier into our image by using COPY command. COPY app.py ./ COPY templates/index.html ./templates/ 8 - Since our Flask application runs on port 5000, we specify that this port should be exposed. This does not automatically publish the port but serves as documentation and can be used by orchestration tools: EXPOSE 5000 9 - The last step is the command for running the application which is simply - python ./app.py . Use the CMD command to do that: CMD [ \"python\" , \"/usr/src/app/app.py\" ] The primary purpose of CMD is to tell the container which command it should run by default when it is started. 10 - Verify your Dockerfile. Our Dockerfile is now ready. This is how it looks: # our base image FROM alpine:3.21.0 # Install Python 3, pip, and system dependencies RUN apk add --no-cache build-base libffi-dev openssl-dev py3-pip python3 # Set the working directory WORKDIR /usr/src/app # Create and activate a virtual environment RUN python3 -m venv venv # Use the virtual environment for all commands ENV PATH = \"/usr/src/app/venv/bin: $PATH \" # Copy and install dependencies COPY requirements.txt ./ RUN pip install --no-cache-dir --upgrade pip && pip install --no-cache-dir -r requirements.txt # Copy application files COPY app.py ./ COPY templates/index.html ./templates/ # Expose the application port EXPOSE 5000 # Run the application inside the virtual environment CMD [ \"python\" , \"/usr/src/app/app.py\" ]","title":"2.3.2 Write a Dockerfile"},{"location":"ch1-discover-docker-td/#233-build-the-image","text":"Now that you have your Dockerfile , you can build your image. The docker build command does the heavy-lifting of creating a docker image from a Dockerfile . When you run the docker build command given below, make sure to replace <YOUR_USERNAME> with your username. This username should be the same one you created when registering on Docker Cloud . If you haven't done that yet, please go ahead and create an account. The docker build command is quite simple - it takes an optional tag name with the -t flag, and the location of the directory containing the Dockerfile - the . indicates the current directory: docker build -t <YOUR_USERNAME>/myfirstapp . If you don't have the alpine:3.21.0 image, the client will first pull the image and then create your image. Therefore, your output on running the command will look different from mine. If everything went well, your image should be ready! Run docker images and see if your image ( <YOUR_USERNAME>/myfirstapp ) shows.","title":"2.3.3 Build the image"},{"location":"ch1-discover-docker-td/#234-run-your-image","text":"The next step in this section is to run the image and see if it actually works. docker run -p 8888 :5000 --name myfirstapp YOUR_USERNAME/myfirstapp * Serving Flask app 'app' * Debug mode: off WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead. * Running on all addresses ( 0 .0.0.0 ) * Running on http://127.0.0.1:5000 * Running on http://172.17.0.2:5000 Press CTRL+C to quit Head over to http://localhost:8888 and your app should be live. Note If you are using Docker Machine, you may need to open up another terminal and determine the container ip address using docker-machine ip default . Hit the Refresh button in the web browser to see a few more cat images. Check Show us your running flask-app !","title":"2.3.4 Run your image"},{"location":"ch1-discover-docker-td/#234-dockerfile-commands-summary","text":"Here's a quick summary of the few basic commands we used in our Dockerfile. FROM starts the Dockerfile. It is a requirement that the Dockerfile must start with the FROM command. Images are created in layers, which means you can use another image as the base image for your own. The FROM command defines your base layer. As arguments, it takes the name of the image. Optionally, you can add the Docker Cloud username of the maintainer and image version, in the format username/imagename:version . RUN is used to build up the Image you're creating. For each RUN command, Docker will run the command then create a new layer of the image. This way you can roll back your image to previous states easily. The syntax for a RUN instruction is to place the full text of the shell command after the RUN (e.g., RUN mkdir /user/local/foo ). This will automatically run in a /bin/sh shell. You can define a different shell like this: RUN /bin/bash -c 'mkdir /user/local/foo ' COPY copies local files into the container. CMD defines the commands that will run on the Image at start-up. Unlike a RUN , this does not create a new layer for the Image, but simply runs the command. There can only be one CMD per a Dockerfile/Image. If you need to run multiple commands, the best way to do that is to have the CMD run a script. CMD requires that you tell it where to run the command, unlike RUN . So example CMD commands would be: CMD [ \"python\" , \"./app.py\" ] CMD [ \"/bin/bash\" , \"echo\" , \"Hello World\" ] EXPOSE creates a hint for users of an image which ports provide services. It is included in the information which can be retrieved via docker inspect <container-id> . Note The EXPOSE command does not actually make any ports accessible to the host! Instead, this requires publishing ports by means of the -p flag when using docker run . Note If you want to learn more about Dockerfiles, check out Best practices for writing Dockerfiles . (source: https://github.com/docker/labs/tree/master/beginner ) Now that you know how to run docker container and create Dockerfiles let\u2019s move on to the practical part.","title":"2.3.4 Dockerfile commands summary"},{"location":"ch1-discover-docker-tp/","text":"Discover Docker Check Checkpoint: do a commit and call us to check your results (don\u2019t stay blocked on a checkpoint if we are busy, we can check \u2154 checkpoints at the same time). Question Point to document/report. Tip Interesting information. Goals Good practice Do not forget to document what you do along the steps, the documentation provided will be evaluated as your report. Create an appropriate file structure, 1 folder per image. Target application 3-tiers application: HTTP server Backend API Database For each of those applications, we will follow the same process: choose the appropriate docker base image, create and configure this image, put our application specifics inside and at some point have it running. Our final goal is to have a 3-tier web API running. Base images HTTP server Backend API Database Database Basics We will use the image: postgres:17.2-alpine. Let\u2019s have a simple postgres server running, here is what would be a minimal Dockerfile: FROM postgres:17.2-alpine ENV POSTGRES_DB = db \\ POSTGRES_USER = usr \\ POSTGRES_PASSWORD = pwd Build this image and start a container properly. Your Postgres DB should be up and running. Check that everything is running smoothly with the docker command of your choice. Don\u2019t forget to name your docker image and container. Tip If you have difficulties go back to part 2.3.3 Build the image and 2.3.4 Run your image on TD01 - Docker ( TD 1 Discover Docker ). Re-run your database with adminer . Don't forget --network app-network to enable adminer/database communication. We use -\u2013network instead of -\u2013link because the latter is deprecated. Tip Don't forget to create your network docker network create app-network Also, does it seem right to have passwords written in plain text in a file? You may rather define those environment parameters when running the image using the flag -e . Question 1-1 For which reason is it better to run the container with a flag -e to give the environment variables rather than put them directly in the Dockerfile? It would be nice to have our database structure initialized with the docker image as well as some initial data. Any sql scripts found in /docker-entrypoint-initdb.d will be executed in alphabetical order, therefore let\u2019s add a couple scripts to our image: Tip Don't forget to restart the adminer: docker run \\ -p \"8090:8080\" \\ --net = app-network \\ --name = adminer \\ -d \\ adminer Init database 01-CreateScheme.sql CREATE TABLE public . departments ( id SERIAL PRIMARY KEY , name VARCHAR ( 20 ) NOT NULL ); CREATE TABLE public . students ( id SERIAL PRIMARY KEY , department_id INT NOT NULL REFERENCES departments ( id ), first_name VARCHAR ( 20 ) NOT NULL , last_name VARCHAR ( 20 ) NOT NULL ); 02-InsertData.sql INSERT INTO departments ( name ) VALUES ( 'IRC' ); INSERT INTO departments ( name ) VALUES ( 'ETI' ); INSERT INTO departments ( name ) VALUES ( 'CGP' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 1 , 'Eli' , 'Copter' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 2 , 'Emma' , 'Carena' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 2 , 'Jack' , 'Uzzi' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 3 , 'Aude' , 'Javel' ); Rebuild your image and check that your scripts have been executed at startup and that the data is present in your container. Tip When we talk about /docker-entrypoint-initdb.d it means inside the container, so you have to copy your directory's content and the container\u2019s directory. Persist data You may have noticed that if your database container gets destroyed then all your data is reset, a database must persist data durably. Use volumes to persist data on the host disk. -v /my/own/datadir:/var/lib/postgresql/data Check that data survives when your container gets destroyed. Link Docker volumes Question 1-2 Why do we need a volume to be attached to our postgres container? Question 1-3 Document your database container essentials: commands and Dockerfile. Backend API Basics For starters, we will simply run a Java hello-world class in our containers, only after will we be running a jar. In both cases, choose the proper image keeping in mind that we only need a Java runtime . Here is a complex Java Hello World implementation: Main.java public class Main { public static void main ( String [] args ) { System . out . println ( \"Hello World!\" ); } } 1- Compile with your target Java: javac Main.java . 2- Write dockerfile. FROM # TODO: Choose a java JRE # TODO: Add the compiled java (aka bytecode, aka .class) # TODO: Run the Java with: \u201cjava Main\u201d command. 3- Now, to launch app you have to do the same thing that Basic step 1. Here you have a first glimpse of your backend application. In the next step we will simply enrich the build (using maven instead of a minimalistic javac) and execute a jar instead of a simple .class. \u2192 If it\u2019s a success you must see \u201cHello Word\u201d in your console. Multistage build In the previous section we were building Java code on our machine to have it running on a docker container. Wouldn\u2019t it be great to have Docker handle the build as well? You probably noticed that the default openjdk docker images contain... Well... a JDK! Create a multistage build using the Multistage . Your Dockerfile should look like this: FROM eclipse-temurin:21-jdk-alpine # Build Main.java with JDK # TODO : in next steps (not now) FROM eclipse-temurin:21-jre-alpine # Copy resource from previous stage COPY --from = 0 /usr/src/Main.class . # Run java code with the JRE # TODO : in next steps (not now) Don\u2019t fill the Dockerfile now, we will have to do it in the next steps. Backend simple api We will deploy a Springboot application providing a simple API with a single greeting endpoint. Create your Springboot application on: Spring Initializer . Use the following config: Project: Maven Language: Java 21 Spring Boot: 3.4.2 Packaging: Jar Dependencies: Spring Web Generate the project and give it a simple GreetingController class: package fr.takima.training.simpleapi.controller ; import org.springframework.web.bind.annotation.* ; import java.util.concurrent.atomic.AtomicLong ; @RestController public class GreetingController { private static final String template = \"Hello, %s!\" ; private final AtomicLong counter = new AtomicLong (); @GetMapping ( \"/\" ) public Greeting greeting ( @RequestParam ( value = \"name\" , defaultValue = \"World\" ) String name ) { return new Greeting ( counter . incrementAndGet (), String . format ( template , name )); } record Greeting ( long id , String content ) {} } You can now build and start your application, of course you will need maven and a jdk-21. How convenient would it be to have a virtual container to build and run our simplistic API? Oh wait, we have docker, here is how you could build and run your application with Docker: # Build stage FROM eclipse-temurin:21-jdk-alpine AS myapp-build ENV MYAPP_HOME = /opt/myapp WORKDIR $MYAPP_HOME RUN apk add --no-cache maven COPY pom.xml . COPY src ./src RUN mvn package -DskipTests # Run stage FROM eclipse-temurin:21-jre-alpine ENV MYAPP_HOME = /opt/myapp WORKDIR $MYAPP_HOME COPY --from = myapp-build $MYAPP_HOME /target/*.jar $MYAPP_HOME /myapp.jar ENTRYPOINT [ \"java\" , \"-jar\" , \"myapp.jar\" ] Question 1-4 Why do we need a multistage build? And explain each step of this dockerfile. Check A working Springboot application with a simple HelloWorld endpoint. Did you notice that maven downloads all libraries on every image build? You can contribute to saving the planet caching libraries when maven pom file has not been changed by running the goal: mvn dependency:go-offline . Backend API Let\u2019s now build and run the backend API connected to the database. You can get the zipped source code here: simple-api . You can replace only your src directory and the pom.xml file with the ones available in the repository. Adjust the configuration in simple-api/src/main/resources/application.yml (this is the application configuration). How to access the database container from your backend application? Use the deprecated --link or create a docker network . Once everything is properly bound, you should be able to access your application API, for example on: /departments/IRC/students . [ { \"id\" : 1 , \"firstname\" : \"Eli\" , \"lastname\" : \"Copter\" , \"department\" : { \"id\" : 1 , \"name\" : \"IRC\" } } ] Explore your API other endpoints, have a look at the controllers in the source code. Check A simple web API on top of your database. Http server Basics Choose an appropriate base image. Create a simple landing page: index.html and put it inside your container. It should be enough for now, start your container and check that everything is working as expected. Here are commands that you may want to try to do so: docker stats docker inspect docker logs Link Httpd Getting Started Configuration You are using the default apache configuration, and it will be enough for now, you use yours by copying it in your image. Use docker exec to retrieve this default configuration from your running container /usr/local/apache2/conf/httpd.conf . Note You can also use docker cp . Reverse proxy We will configure the http server as a simple reverse proxy server in front of our application, this server could be used to deliver a front-end application, to configure SSL or to handle load balancing. So this can be quite useful even though in our case we will keep things simple. Here is the documentation: Reverse Proxy . Add the following to the configuration, and you should be all set: <VirtualHost *:80> ProxyPreserveHost On ProxyPass / http://YOUR_BACKEND_LINK:8080/ ProxyPassReverse / http://YOUR_BACKEND_LINK:8080/ </VirtualHost> LoadModule proxy_module modules/mod_proxy.so LoadModule proxy_http_module modules/mod_proxy_http.so Question 1-5 Why do we need a reverse proxy? Check Checkpoint: a working application through a reverse proxy. Link application Docker-compose 1- Install docker-compose if the docker compose command does not work . You may have noticed that this can be quite painful to orchestrate manually the start, stop and rebuild of our containers. Thankfully, a useful tool called docker-compose comes in handy in those situations. 2- Let\u2019s create a docker-compose.yml file with the following structure to define and drive our containers: services : backend : build : #TODO networks : #TODO depends_on : #TODO database : build : #TODO networks : #TODO httpd : build : #TODO ports : #TODO networks : #TODO depends_on : #TODO networks : #TODO volumes : #TODO The docker-compose will handle the three containers for us. The file above is a basic example of structure, you need to add more parameters and think about the cleanest and most optimized approach like you would do in a company (for example: env variables, volumes, restart policies and processes segregation). Once your containers are orchestrated as services by docker-compose you should have a perfectly running application, make sure you can access your API on localhost . Note The ports of both your backend and database should not be opened to your host machine. Question 1-6 Why is docker-compose so important? Question 1-7 Document docker-compose most important commands. Question 1-8 Document your docker-compose file. Check A working 3-tier application running with docker-compose. Publish Your docker images are stored locally, let\u2019s publish them, so they can be used by other team members or on other machines. You will need a Docker Hub account. 1- Connect to your freshly created account with docker login . 2- Tag your image. For now, we have been only using the latest tag, now that we want to publish it, let\u2019s add some meaningful version information to our images. docker tag my-database USERNAME/my-database:1.0 3- Then push your image to dockerhub: docker push USERNAME/my-database:1.0 Dockerhub is not the only docker image registry, and you can also self-host your images (this is obviously the choice of most companies). Once you publish your images to dockerhub, you will see them in your account: having some documentation for your image would be quite useful if you want to use those later. Question 1-9 Document your publication commands and published images in dockerhub. Question 1-10 Why do we put our images into an online repo? \u00a9 Takima 2025","title":"TP part 01 - Docker"},{"location":"ch1-discover-docker-tp/#discover-docker","text":"Check Checkpoint: do a commit and call us to check your results (don\u2019t stay blocked on a checkpoint if we are busy, we can check \u2154 checkpoints at the same time). Question Point to document/report. Tip Interesting information.","title":"Discover Docker"},{"location":"ch1-discover-docker-tp/#goals","text":"","title":"Goals"},{"location":"ch1-discover-docker-tp/#good-practice","text":"Do not forget to document what you do along the steps, the documentation provided will be evaluated as your report. Create an appropriate file structure, 1 folder per image.","title":"Good practice"},{"location":"ch1-discover-docker-tp/#target-application","text":"3-tiers application: HTTP server Backend API Database For each of those applications, we will follow the same process: choose the appropriate docker base image, create and configure this image, put our application specifics inside and at some point have it running. Our final goal is to have a 3-tier web API running.","title":"Target application"},{"location":"ch1-discover-docker-tp/#base-images","text":"HTTP server Backend API Database","title":"Base images"},{"location":"ch1-discover-docker-tp/#database","text":"","title":"Database"},{"location":"ch1-discover-docker-tp/#basics","text":"We will use the image: postgres:17.2-alpine. Let\u2019s have a simple postgres server running, here is what would be a minimal Dockerfile: FROM postgres:17.2-alpine ENV POSTGRES_DB = db \\ POSTGRES_USER = usr \\ POSTGRES_PASSWORD = pwd Build this image and start a container properly. Your Postgres DB should be up and running. Check that everything is running smoothly with the docker command of your choice. Don\u2019t forget to name your docker image and container. Tip If you have difficulties go back to part 2.3.3 Build the image and 2.3.4 Run your image on TD01 - Docker ( TD 1 Discover Docker ). Re-run your database with adminer . Don't forget --network app-network to enable adminer/database communication. We use -\u2013network instead of -\u2013link because the latter is deprecated. Tip Don't forget to create your network docker network create app-network Also, does it seem right to have passwords written in plain text in a file? You may rather define those environment parameters when running the image using the flag -e . Question 1-1 For which reason is it better to run the container with a flag -e to give the environment variables rather than put them directly in the Dockerfile? It would be nice to have our database structure initialized with the docker image as well as some initial data. Any sql scripts found in /docker-entrypoint-initdb.d will be executed in alphabetical order, therefore let\u2019s add a couple scripts to our image: Tip Don't forget to restart the adminer: docker run \\ -p \"8090:8080\" \\ --net = app-network \\ --name = adminer \\ -d \\ adminer","title":"Basics"},{"location":"ch1-discover-docker-tp/#init-database","text":"01-CreateScheme.sql CREATE TABLE public . departments ( id SERIAL PRIMARY KEY , name VARCHAR ( 20 ) NOT NULL ); CREATE TABLE public . students ( id SERIAL PRIMARY KEY , department_id INT NOT NULL REFERENCES departments ( id ), first_name VARCHAR ( 20 ) NOT NULL , last_name VARCHAR ( 20 ) NOT NULL ); 02-InsertData.sql INSERT INTO departments ( name ) VALUES ( 'IRC' ); INSERT INTO departments ( name ) VALUES ( 'ETI' ); INSERT INTO departments ( name ) VALUES ( 'CGP' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 1 , 'Eli' , 'Copter' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 2 , 'Emma' , 'Carena' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 2 , 'Jack' , 'Uzzi' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 3 , 'Aude' , 'Javel' ); Rebuild your image and check that your scripts have been executed at startup and that the data is present in your container. Tip When we talk about /docker-entrypoint-initdb.d it means inside the container, so you have to copy your directory's content and the container\u2019s directory.","title":"Init database"},{"location":"ch1-discover-docker-tp/#persist-data","text":"You may have noticed that if your database container gets destroyed then all your data is reset, a database must persist data durably. Use volumes to persist data on the host disk. -v /my/own/datadir:/var/lib/postgresql/data Check that data survives when your container gets destroyed. Link Docker volumes Question 1-2 Why do we need a volume to be attached to our postgres container? Question 1-3 Document your database container essentials: commands and Dockerfile.","title":"Persist data"},{"location":"ch1-discover-docker-tp/#backend-api","text":"","title":"Backend API"},{"location":"ch1-discover-docker-tp/#basics_1","text":"For starters, we will simply run a Java hello-world class in our containers, only after will we be running a jar. In both cases, choose the proper image keeping in mind that we only need a Java runtime . Here is a complex Java Hello World implementation: Main.java public class Main { public static void main ( String [] args ) { System . out . println ( \"Hello World!\" ); } } 1- Compile with your target Java: javac Main.java . 2- Write dockerfile. FROM # TODO: Choose a java JRE # TODO: Add the compiled java (aka bytecode, aka .class) # TODO: Run the Java with: \u201cjava Main\u201d command. 3- Now, to launch app you have to do the same thing that Basic step 1. Here you have a first glimpse of your backend application. In the next step we will simply enrich the build (using maven instead of a minimalistic javac) and execute a jar instead of a simple .class. \u2192 If it\u2019s a success you must see \u201cHello Word\u201d in your console.","title":"Basics"},{"location":"ch1-discover-docker-tp/#multistage-build","text":"In the previous section we were building Java code on our machine to have it running on a docker container. Wouldn\u2019t it be great to have Docker handle the build as well? You probably noticed that the default openjdk docker images contain... Well... a JDK! Create a multistage build using the Multistage . Your Dockerfile should look like this: FROM eclipse-temurin:21-jdk-alpine # Build Main.java with JDK # TODO : in next steps (not now) FROM eclipse-temurin:21-jre-alpine # Copy resource from previous stage COPY --from = 0 /usr/src/Main.class . # Run java code with the JRE # TODO : in next steps (not now) Don\u2019t fill the Dockerfile now, we will have to do it in the next steps.","title":"Multistage build"},{"location":"ch1-discover-docker-tp/#backend-simple-api","text":"We will deploy a Springboot application providing a simple API with a single greeting endpoint. Create your Springboot application on: Spring Initializer . Use the following config: Project: Maven Language: Java 21 Spring Boot: 3.4.2 Packaging: Jar Dependencies: Spring Web Generate the project and give it a simple GreetingController class: package fr.takima.training.simpleapi.controller ; import org.springframework.web.bind.annotation.* ; import java.util.concurrent.atomic.AtomicLong ; @RestController public class GreetingController { private static final String template = \"Hello, %s!\" ; private final AtomicLong counter = new AtomicLong (); @GetMapping ( \"/\" ) public Greeting greeting ( @RequestParam ( value = \"name\" , defaultValue = \"World\" ) String name ) { return new Greeting ( counter . incrementAndGet (), String . format ( template , name )); } record Greeting ( long id , String content ) {} } You can now build and start your application, of course you will need maven and a jdk-21. How convenient would it be to have a virtual container to build and run our simplistic API? Oh wait, we have docker, here is how you could build and run your application with Docker: # Build stage FROM eclipse-temurin:21-jdk-alpine AS myapp-build ENV MYAPP_HOME = /opt/myapp WORKDIR $MYAPP_HOME RUN apk add --no-cache maven COPY pom.xml . COPY src ./src RUN mvn package -DskipTests # Run stage FROM eclipse-temurin:21-jre-alpine ENV MYAPP_HOME = /opt/myapp WORKDIR $MYAPP_HOME COPY --from = myapp-build $MYAPP_HOME /target/*.jar $MYAPP_HOME /myapp.jar ENTRYPOINT [ \"java\" , \"-jar\" , \"myapp.jar\" ] Question 1-4 Why do we need a multistage build? And explain each step of this dockerfile. Check A working Springboot application with a simple HelloWorld endpoint. Did you notice that maven downloads all libraries on every image build? You can contribute to saving the planet caching libraries when maven pom file has not been changed by running the goal: mvn dependency:go-offline .","title":"Backend simple api"},{"location":"ch1-discover-docker-tp/#backend-api_1","text":"Let\u2019s now build and run the backend API connected to the database. You can get the zipped source code here: simple-api . You can replace only your src directory and the pom.xml file with the ones available in the repository. Adjust the configuration in simple-api/src/main/resources/application.yml (this is the application configuration). How to access the database container from your backend application? Use the deprecated --link or create a docker network . Once everything is properly bound, you should be able to access your application API, for example on: /departments/IRC/students . [ { \"id\" : 1 , \"firstname\" : \"Eli\" , \"lastname\" : \"Copter\" , \"department\" : { \"id\" : 1 , \"name\" : \"IRC\" } } ] Explore your API other endpoints, have a look at the controllers in the source code. Check A simple web API on top of your database.","title":"Backend API"},{"location":"ch1-discover-docker-tp/#http-server","text":"","title":"Http server"},{"location":"ch1-discover-docker-tp/#basics_2","text":"","title":"Basics"},{"location":"ch1-discover-docker-tp/#choose-an-appropriate-base-image","text":"Create a simple landing page: index.html and put it inside your container. It should be enough for now, start your container and check that everything is working as expected. Here are commands that you may want to try to do so: docker stats docker inspect docker logs Link Httpd Getting Started","title":"Choose an appropriate base image."},{"location":"ch1-discover-docker-tp/#configuration","text":"You are using the default apache configuration, and it will be enough for now, you use yours by copying it in your image. Use docker exec to retrieve this default configuration from your running container /usr/local/apache2/conf/httpd.conf . Note You can also use docker cp .","title":"Configuration"},{"location":"ch1-discover-docker-tp/#reverse-proxy","text":"We will configure the http server as a simple reverse proxy server in front of our application, this server could be used to deliver a front-end application, to configure SSL or to handle load balancing. So this can be quite useful even though in our case we will keep things simple. Here is the documentation: Reverse Proxy . Add the following to the configuration, and you should be all set: <VirtualHost *:80> ProxyPreserveHost On ProxyPass / http://YOUR_BACKEND_LINK:8080/ ProxyPassReverse / http://YOUR_BACKEND_LINK:8080/ </VirtualHost> LoadModule proxy_module modules/mod_proxy.so LoadModule proxy_http_module modules/mod_proxy_http.so Question 1-5 Why do we need a reverse proxy? Check Checkpoint: a working application through a reverse proxy.","title":"Reverse proxy"},{"location":"ch1-discover-docker-tp/#link-application","text":"","title":"Link application"},{"location":"ch1-discover-docker-tp/#docker-compose","text":"1- Install docker-compose if the docker compose command does not work . You may have noticed that this can be quite painful to orchestrate manually the start, stop and rebuild of our containers. Thankfully, a useful tool called docker-compose comes in handy in those situations. 2- Let\u2019s create a docker-compose.yml file with the following structure to define and drive our containers: services : backend : build : #TODO networks : #TODO depends_on : #TODO database : build : #TODO networks : #TODO httpd : build : #TODO ports : #TODO networks : #TODO depends_on : #TODO networks : #TODO volumes : #TODO The docker-compose will handle the three containers for us. The file above is a basic example of structure, you need to add more parameters and think about the cleanest and most optimized approach like you would do in a company (for example: env variables, volumes, restart policies and processes segregation). Once your containers are orchestrated as services by docker-compose you should have a perfectly running application, make sure you can access your API on localhost . Note The ports of both your backend and database should not be opened to your host machine. Question 1-6 Why is docker-compose so important? Question 1-7 Document docker-compose most important commands. Question 1-8 Document your docker-compose file. Check A working 3-tier application running with docker-compose.","title":"Docker-compose"},{"location":"ch1-discover-docker-tp/#publish","text":"Your docker images are stored locally, let\u2019s publish them, so they can be used by other team members or on other machines. You will need a Docker Hub account. 1- Connect to your freshly created account with docker login . 2- Tag your image. For now, we have been only using the latest tag, now that we want to publish it, let\u2019s add some meaningful version information to our images. docker tag my-database USERNAME/my-database:1.0 3- Then push your image to dockerhub: docker push USERNAME/my-database:1.0 Dockerhub is not the only docker image registry, and you can also self-host your images (this is obviously the choice of most companies). Once you publish your images to dockerhub, you will see them in your account: having some documentation for your image would be quite useful if you want to use those later. Question 1-9 Document your publication commands and published images in dockerhub. Question 1-10 Why do we put our images into an online repo? \u00a9 Takima 2025","title":"Publish"},{"location":"cheatsheet/","text":"Cheatsheet Docker & docker-compose","title":"Cheatsheet"},{"location":"cheatsheet/#cheatsheet","text":"","title":"Cheatsheet"},{"location":"cheatsheet/#docker-docker-compose","text":"","title":"Docker &amp; docker-compose"}]}
\ No newline at end of file
+{"config":{"indexing":"full","lang":["en"],"min_search_length":3,"prebuild_index":false,"separator":"[\\s\\-]+"},"docs":[{"location":"","text":"Devops in Action - Guide For each step you have a TD to discover the subject and a TP to put it into practice. The TPs follow each other and the goal is to make you start from a local application and get to an application delivered in production and accessible to all. For that we will give you each a server and a Java application. Part 1 - Docker session Docker TDs are available here Docker TPs are available here Docker slides are available here Please read the indications carefully, most of the time what you need is in front of your eyes! \u00a9 Takima 2025","title":"Devops in Action - Guide"},{"location":"#devops-in-action-guide","text":"For each step you have a TD to discover the subject and a TP to put it into practice. The TPs follow each other and the goal is to make you start from a local application and get to an application delivered in production and accessible to all. For that we will give you each a server and a Java application. Part 1 - Docker session Docker TDs are available here Docker TPs are available here Docker slides are available here Please read the indications carefully, most of the time what you need is in front of your eyes! \u00a9 Takima 2025","title":"Devops in Action - Guide"},{"location":"ch1-discover-docker-td/","text":"Discover Docker Check Checkpoint: do a commit and call us to check your results (don\u2019t stay blocked on a checkpoint if we are busy, we can check \u2154 checkpoints at the same time) Question Point to document/report Tip Interesting information Setup Prerequisites There are no specific skills needed for this tutorial beyond a basic comfort with the command line and using a text editor. Prior experience in developing web applications will be helpful but is not required. As you proceed further along the tutorial, we'll make use of https://cloud.docker.com/. Setting up your computer Getting all the tooling setup on your computer can be a daunting task, but getting Docker up and running on your favorite OS has become very easy. The getting started guide on Docker has detailed instructions for setting up Docker on Mac , Linux and Windows If you're using Docker for Windows make sure you have shared your drive. Important note If you're using an older version of Windows or MacOS you may need to use Docker Machine instead. All commands work in either bash or Powershell on Windows Once you are done installing Docker, test your Docker installation by running the following: docker run hello-world Unable to find image 'hello-world:latest' locally latest: Pulling from library/hello-world 03f4658f8b78: Pull complete a3ed95caeb02: Pull complete Digest: sha256:8be990ef2aeb16dbcb9271ddfe2610fa6658d13f6dfb8bc72074cc1ca36966a7 Status: Downloaded newer image for hello-world:latest Hello from Docker. ... This message shows that your installation appears to be working correctly. Running your first container Now that you have everything setup, it's time to get our hands dirty. In this section, you are going to run an Alpine Linux container (a lightweight linux distribution) on your system and get a taste of the docker run command. To get started, let's run the following in our terminal: docker pull alpine Note Depending on how you've installed docker on your system, you might see a permission denied error after running the above command. Try the commands from the Getting Started tutorial to verify your installation . If you're on Linux, you may need to prefix your docker commands with sudo . Alternatively you can create a docker group to get rid of this issue. The pull command fetches the alpine image from the Docker registry and saves it in our system. You can use the docker images command to see a list of all images on your system. docker images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE alpine latest c51f86c28340 4 weeks ago 1 .109 MB hello-world latest 690ed74de00f 5 months ago 960 B 1.1 Docker Run Great! Let's now run a Docker container based on this image. To do that you are going to use the docker run command. docker run alpine ls -l total 48 drwxr-xr-x 2 root root 4096 Mar 2 16:20 bin drwxr-xr-x 5 root root 360 Mar 18 09:47 dev drwxr-xr-x 13 root root 4096 Mar 18 09:47 etc drwxr-xr-x 2 root root 4096 Mar 2 16:20 home drwxr-xr-x 5 root root 4096 Mar 2 16:20 lib ...... ...... What happened? Behind the scenes, a lot of stuff happened. When you call run : 1. The Docker client contacts the Docker daemon. The Docker daemon checks local store if the image (alpine in this case) is available locally, and if not, downloads it from Docker Store. (Since we have issued docker pull alpine before, the download step is not necessary) The Docker daemon creates the container and then runs a command in that container. The Docker daemon streams the output of the command to the Docker client When you run docker run alpine , you provided a command ( ls -l ), so Docker started the command specified and you saw the listing. Let's try something more exciting. docker run alpine echo \"hello from alpine\" hello from alpine OK, that's some actual output. In this case, the Docker client dutifully ran the echo command in our alpine container and then exited it. If you've noticed, all of that happened pretty quickly. Imagine booting up a virtual machine, running a command and then killing it. Now you know why they say containers are fast! Try another command. docker run alpine /bin/sh Wait, nothing happened! Is that a bug? Well, no. These interactive shells will exit after running any scripted commands, unless they are run in an interactive terminal - so for this example to not exit, you need to docker run -it alpine /bin/sh . You are now inside the container shell and you can try out a few commands like ls -l , uname -a and others. Exit out of the container by giving the exit command. Ok, now it's time to see the docker ps command. The docker ps command shows you all containers that are currently running. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES Since no containers are running, you see a blank line. Let's try a more useful variant: docker ps -a docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 36171a5da744 alpine \"/bin/sh\" 5 minutes ago Exited ( 0 ) 2 minutes ago fervent_newton a6a9d46d0b2f alpine \"echo 'hello from alp\" 6 minutes ago Exited ( 0 ) 6 minutes ago lonely_kilby ff0a5c3750b9 alpine \"ls -l\" 8 minutes ago Exited ( 0 ) 8 minutes ago elated_ramanujan c317d0a9e3d2 hello-world \"/hello\" 34 seconds ago Exited ( 0 ) 12 minutes ago stupefied_mcclintock What you see above is a list of all containers that you ran. Notice that the STATUS column shows that these containers exited a few minutes ago. You're probably wondering if there is a way to run more than just one command in a container. Let's try that now: docker run -it alpine /bin/sh / # ls bin dev etc home lib linuxrc media mnt proc root run sbin sys tmp usr var / # uname -a Linux 97916e8cb5dc 4.4.27-moby #1 SMP Wed Oct 26 14:01:48 UTC 2016 x86_64 Linux Running the run command with the -it flags attaches us to an interactive tty in the container. Now you can run as many commands in the container as you want. Take some time to run your favorite commands. Tip run -it is a very useful command to debug at the lowest level a container. That concludes a whirlwind tour of the docker run command which would most likely be the command you'll use most often. It makes sense to spend some time getting comfortable with it. To find out more about run , use docker run --help to see a list of all flags it supports. As you proceed further, we'll see a few more variants of docker run. 1.2 Terminology In the last section, you saw a lot of Docker-specific jargon which might be confusing to some. So before you go further, let's clarify some terminology that is used frequently in the Docker ecosystem. Images - The file system and configuration of our application which are used to create containers. To find out more about a Docker image, run docker inspect alpine . In the demo above, you used the docker pull command to download the alpine image. When you executed the command docker run hello-world , it also did a docker pull behind the scenes to download the hello-world image. Containers - Running instances of Docker images \u2014 containers run the actual applications. A container includes an application and all of its dependencies. It shares the kernel with other containers, and runs as an isolated process in user space on the host OS. You created a container using docker run which you did using the alpine image that you downloaded. A list of running containers can be seen using the docker ps command. Docker daemon - The background service running on the host that manages building, running and distributing Docker containers. Docker client - The command line tool that allows the user to interact with the Docker daemon. Docker Store - A registry of Docker images, where you can find trusted and enterprise ready containers, plugins, and Docker editions. You'll be using this later in this tutorial. 2.0 Webapps with Docker Great! So you have now looked at docker run , played with a Docker container and also got the hang of some terminology. Armed with all this knowledge, you are now ready to get to the real stuff \u2014 deploying web applications with Docker. 2.1 Run a static website in a container Note Code for this section is in this repo in the static-site directory Let's start by taking baby-steps. First, we'll use Docker to run a static website in a container. The website is based on an existing image. We'll pull a Docker image from Docker Store, run the container, and see how easy it is to set up a web server. The image that you are going to use is a single-page website that was already created for this demo and is available on the Docker Store as dockersamples/static-site . You can download and run the image directly in one go using docker run as follows. docker run -d dockersamples/static-site Note The current version of this image doesn't run without the -d flag. The -d flag enables detached mode, which detaches the running container from the terminal/shell and returns your prompt after the container starts. We are debugging the problem with this image but for now, use -d even for this first example. Tip -d is a very useful option. So, what happens when you run this command? Since the image doesn't exist on your Docker host, the Docker daemon first fetches it from the registry and then runs it as a container. Now that the server is running, do you see the website? What port is it running on? And more importantly, how do you access the container directly from our host machine? Actually, you probably won't be able to answer any of these questions yet! \u263a In this case, the client didn't tell the Docker Engine to publish any of the ports, so you need to re-run the docker run command to add this instruction. Let's re-run the command with some new flags to publish ports and pass your name to the container to customize the message displayed. We'll use the -d option again to run the container in detached mode. First, stop the container that you have just launched. In order to do this, we need the container ID. Since we ran the container in detached mode, we don't have to launch another terminal to do this. Run docker ps to view the running containers. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES a7a0e504ca3e dockersamples/static-site \"/bin/sh -c 'cd /usr/\" 28 seconds ago Up 26 seconds 80 /tcp, 443 /tcp stupefied_mahavira Check out the CONTAINER ID column. You will need to use this CONTAINER ID value, a long sequence of characters, to identify the container you want to stop, and then to remove it. The example below provides the CONTAINER ID on our system; you should use the value that you see in your terminal. docker stop a7a0e504ca3e docker rm a7a0e504ca3e Note A cool feature is that you do not need to specify the entire CONTAINER ID . You can just specify a few starting characters and if it is unique among all the containers that you have launched, the Docker client will intelligently pick it up. Now, let's launch a container in detached mode as shown below: docker run --name static-site -e AUTHOR = \"Enter Your Name Here\" -d -P dockersamples/static-site e61d12292d69556eabe2a44c16cbd54486b2527e2ce4f95438e504afb7b02810 In the above command: -d will create a container with the process detached from our terminal -P will publish all the exposed container ports to random ports on the Docker host -e is how you pass environment variables to the container. --name allows you to specify a container name AUTHOR is the environment variable name and Your Name is the value that you can pass. Now you can see the ports by running the docker port command. docker port static-site 443 /tcp -> 0 .0.0.0:32772 80 /tcp -> 0 .0.0.0:32773 You can open your freshly created website on http://localhost:[YOUR_PORT_FOR 80/tcp] . For our example this is http://localhost:32773 . You can now open http://localhost:[YOUR_PORT_FOR 80/tcp] to see your site live! For our example, this is: http://192.168.99.100:32773 . You can also run a second webserver at the same time, specifying a custom host port mapping to the container's webserver. docker run --name static-site-2 -e AUTHOR = \"Enter Your Name Here\" -d -p 8888 :80 dockersamples/static-site To deploy this on a real server you would just need to install Docker, and run the above docker command (as in this case you can see the AUTHOR is Docker which we passed as an environment variable). Now that you've seen how to run a webserver inside a Docker container, how do you create your own Docker image? This is the question we'll explore in the next section. But first, let's stop and remove the containers since you won't be using them anymore. docker stop static-site docker rm static-site Let's use a shortcut to remove the second site: docker rm -f static-site-2 Tip rm -f is a very useful option Run docker ps to make sure the containers are gone. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 2.2 Docker Images In this section, let's dive deeper into what Docker images are. You will build your own image, use that image to run an application locally, and finally, push some of your own images to Docker Cloud. Docker images are the basis of containers. In the previous example, you pulled the dockersamples/static-site image from the. registry and asked the Docker client to run a container based on that image. To see the list of images that are available locally on your system, run the docker images command. docker images REPOSITORY TAG IMAGE ID CREATED SIZE dockersamples/static-site latest 92a386b6e686 2 hours ago 190 .5 MB nginx latest af4b3d7d5401 3 hours ago 190 .5 MB python 2 .7 1c32174fd534 14 hours ago 676 .8 MB postgres 9 .4 88d845ac7a88 14 hours ago 263 .6 MB containous/traefik latest 27b4e0c6b2fd 4 days ago 20 .75 MB node 0 .10 42426a5cba5f 6 days ago 633 .7 MB redis latest 4f5f397d4b7c 7 days ago 177 .5 MB mongo latest 467eb21035a8 7 days ago 309 .7 MB alpine 3 .3 70c557e50ed6 8 days ago 4 .794 MB java 7 21f6ce84e43c 8 days ago 587 .7 MB Above is a list of images that I've pulled from the registry and those I've created myself (we'll shortly see how). You will have a different list of images on your machine. The TAG refers to a particular snapshot of the image and the ID is the corresponding unique identifier for that image. For simplicity, you can think of an image akin to a git repository - images can be committed with changes and have multiple. versions. When you do not provide a specific version number, the client defaults to latest. For example you could pull a specific version of ubuntu image as follows: docker pull ubuntu:12.04 If you do not specify the version number of the image then, as mentioned, the Docker client will default to a version named latest . So for example, the docker pull command given below will pull an image named ubuntu:latest : docker pull ubuntu To get a new Docker image you can either get it from a registry (such as the Docker Store) or create your own. There are hundreds of thousands of images available on Docker Store . You can also search for images directly from the command line using docker search . An important distinction with regard to images is between base images and child images . Base images are images that have no parent images, usually images with an OS like ubuntu, alpine or debian. Child images are images that build on base images and add additional functionality. Another key concept is the idea of official images and user images. (Both of which can be base images or child images.) Official images are Docker sanctioned images. Docker, Inc. sponsors a dedicated team that is responsible for reviewing and publishing all Official Repositories content. This team works in collaboration with upstream software maintainers, security experts, and the broader Docker community. These are not prefixed by an organization or user name. In the list of images above, the python , node , alpine and nginx images are official (base) images. To find out more about them, check out the Official Images Documentation . User images are images created and shared by users like you. They build on base images and add additional functionality. Typically these are formatted as user/image-name . The user value in the image name is your Docker Store user or organization name. 2.3 Create your first image Now that you have a better understanding of images, it's time to create your own. Our main objective here is to create an image that sandboxes a small Flask application. The goal of this exercise is to create a Docker image which will run a Flask app. We'll do this by first pulling together the components for a random cat picture generator built with Python Flask, then dockerizing it by writing a Dockerfile . Finally, we'll build the image, and then run it. 2.3.1 Create a Python Flask app that displays random cat pix. For the purposes of this workshop, we've created a fun little Python Flask app that displays a random cat .gif every time it is loaded - because, you know, who doesn't like cats? Start by creating a directory called flask-app where we'll create the following files: app.py requirements.txt templates/index.html Dockerfile Make sure to cd flask-app before you start creating the files, because you don't want to start adding a whole bunch of other random files to your image. app.py Create the app.py with the following content: from flask import Flask , render_template import random app = Flask ( __name__ ) # list of cat images images = [ \"https://c.tenor.com/GTcT7HODLRgAAAAM/smiling-cat-creepy-cat.gif\" , \"https://media0.giphy.com/media/10dU7AN7xsi1I4/giphy.webp?cid=ecf05e47gk63rd81vzlot57qmebr7drtgf6a3khmzvjsdtu7&rid=giphy.webp&ct=g\" , \"https://media0.giphy.com/media/S6VGjvmFRu5Qk/giphy.webp?cid=ecf05e478yofpawrhffnnvb3sgjkos96vyfo5mtqhds35as6&rid=giphy.webp&ct=g\" , \"https://media3.giphy.com/media/JIX9t2j0ZTN9S/200w.webp?cid=ecf05e47gk63rd81vzlot57qmebr7drtgf6a3khmzvjsdtu7&rid=200w.webp&ct=g\" ] @app . route ( '/' ) def index (): url = random . choice ( images ) return render_template ( 'index.html' , url = url ) if __name__ == \"__main__\" : app . run ( host = \"0.0.0.0\" ) requirements.txt In order to install the Python modules required for our app, we need to create a file called requirements.txt and add the following line to that file: Flask==3.1.0 templates/index.html Create a directory called templates and create an index.html file in that directory with the following content in it: < html > < head > < style type = \"text/css\" > body { background : black ; color : white ; } div . container { max-width : 500 px ; margin : 100 px auto ; border : 20 px solid white ; padding : 10 px ; text-align : center ; } h4 { text-transform : uppercase ; } </ style > </ head > < body > < div class = \"container\" > < h4 > Cat Gif of the day </ h4 > < img src = \"{{url}}\" /> < p >< small > Courtesy: < a href = \"http://www.buzzfeed.com/copyranter/the-best-cat-gif-post-in-the-history-of-cat-gifs\" > Buzzfeed </ a ></ small ></ p > </ div > </ body > </ html > 2.3.2 Write a Dockerfile We want to create a Docker image with this web app. As mentioned above, all user images are based on a base image. Since our application is written in Python, we will build our own Python image based on Alpine . We'll do that using a Dockerfile. A Dockerfile is a text file that contains a list of commands that the Docker daemon calls while creating an image. The Dockerfile contains all the information that Docker needs to know to run the app \u2014 a base Docker image to run from, location of your project code, any dependencies it has, and what commands to run at start-up. It is a simple way to automate the image creation process. The best part is that the commands you write in a Dockerfile are almost identical to their equivalent Linux commands. This means you don't really have to learn new syntax to create your own Dockerfiles. 1 - Create a file called Dockerfile, and add content to it as described below. We'll start by specifying our base image, using the FROM keyword. We are using alpine:3.21.0, a lightweight Linux distribution that helps keep our container small and efficient: FROM alpine:3.21.0 2 - Next, we need to install Python 3, pip, and other system dependencies required for our application. The apk add command is used to install packages in Alpine Linux. We use --no-cache to prevent unnecessary image bloat. Add the following RUN command: RUN apk add --no-cache build-base libffi-dev openssl-dev py3-pip python3 3 - Now, we set the working directory inside the container. This ensures that all subsequent commands run within this directory: WORKDIR /usr/src/app 4 - To create an isolated Python environment, we set up a virtual environment inside our container. This helps prevent conflicts between system-wide and project-specific dependencies: RUN python3 -m venv venv 5 - To ensure that all commands within the container use the virtual environment by default, we modify the PATH environment variable: ENV PATH = \"/usr/src/app/venv/bin: $PATH \" 6 - Next, we copy the application's dependencies file (requirements.txt) into the container and install the necessary Python packages. We also upgrade pip to the latest version to ensure compatibility: COPY requirements.txt ./ RUN pip install --no-cache-dir --upgrade pip && pip install --no-cache-dir -r requirements.txt 7 - Copy the files you have created earlier into our image by using COPY command. COPY app.py ./ COPY templates/index.html ./templates/ 8 - Since our Flask application runs on port 5000, we specify that this port should be exposed. This does not automatically publish the port but serves as documentation and can be used by orchestration tools: EXPOSE 5000 9 - The last step is the command for running the application which is simply - python ./app.py . Use the CMD command to do that: CMD [ \"python\" , \"/usr/src/app/app.py\" ] The primary purpose of CMD is to tell the container which command it should run by default when it is started. 10 - Verify your Dockerfile. Our Dockerfile is now ready. This is how it looks: # our base image FROM alpine:3.21.0 # Install Python 3, pip, and system dependencies RUN apk add --no-cache build-base libffi-dev openssl-dev py3-pip python3 # Set the working directory WORKDIR /usr/src/app # Create and activate a virtual environment RUN python3 -m venv venv # Use the virtual environment for all commands ENV PATH = \"/usr/src/app/venv/bin: $PATH \" # Copy and install dependencies COPY requirements.txt ./ RUN pip install --no-cache-dir --upgrade pip && pip install --no-cache-dir -r requirements.txt # Copy application files COPY app.py ./ COPY templates/index.html ./templates/ # Expose the application port EXPOSE 5000 # Run the application inside the virtual environment CMD [ \"python\" , \"/usr/src/app/app.py\" ] 2.3.3 Build the image Now that you have your Dockerfile , you can build your image. The docker build command does the heavy-lifting of creating a docker image from a Dockerfile . When you run the docker build command given below, make sure to replace <YOUR_USERNAME> with your username. This username should be the same one you created when registering on Docker Cloud . If you haven't done that yet, please go ahead and create an account. The docker build command is quite simple - it takes an optional tag name with the -t flag, and the location of the directory containing the Dockerfile - the . indicates the current directory: docker build -t <YOUR_USERNAME>/myfirstapp . If you don't have the alpine:3.21.0 image, the client will first pull the image and then create your image. Therefore, your output on running the command will look different from mine. If everything went well, your image should be ready! Run docker images and see if your image ( <YOUR_USERNAME>/myfirstapp ) shows. 2.3.4 Run your image The next step in this section is to run the image and see if it actually works. docker run -p 8888 :5000 --name myfirstapp YOUR_USERNAME/myfirstapp * Serving Flask app 'app' * Debug mode: off WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead. * Running on all addresses ( 0 .0.0.0 ) * Running on http://127.0.0.1:5000 * Running on http://172.17.0.2:5000 Press CTRL+C to quit Head over to http://localhost:8888 and your app should be live. Note If you are using Docker Machine, you may need to open up another terminal and determine the container ip address using docker-machine ip default . Hit the Refresh button in the web browser to see a few more cat images. Check Show us your running flask-app ! 2.3.4 Dockerfile commands summary Here's a quick summary of the few basic commands we used in our Dockerfile. FROM starts the Dockerfile. It is a requirement that the Dockerfile must start with the FROM command. Images are created in layers, which means you can use another image as the base image for your own. The FROM command defines your base layer. As arguments, it takes the name of the image. Optionally, you can add the Docker Cloud username of the maintainer and image version, in the format username/imagename:version . RUN is used to build up the Image you're creating. For each RUN command, Docker will run the command then create a new layer of the image. This way you can roll back your image to previous states easily. The syntax for a RUN instruction is to place the full text of the shell command after the RUN (e.g., RUN mkdir /user/local/foo ). This will automatically run in a /bin/sh shell. You can define a different shell like this: RUN /bin/bash -c 'mkdir /user/local/foo ' COPY copies local files into the container. CMD defines the commands that will run on the Image at start-up. Unlike a RUN , this does not create a new layer for the Image, but simply runs the command. There can only be one CMD per a Dockerfile/Image. If you need to run multiple commands, the best way to do that is to have the CMD run a script. CMD requires that you tell it where to run the command, unlike RUN . So example CMD commands would be: CMD [ \"python\" , \"./app.py\" ] CMD [ \"/bin/bash\" , \"echo\" , \"Hello World\" ] EXPOSE creates a hint for users of an image which ports provide services. It is included in the information which can be retrieved via docker inspect <container-id> . Note The EXPOSE command does not actually make any ports accessible to the host! Instead, this requires publishing ports by means of the -p flag when using docker run . Note If you want to learn more about Dockerfiles, check out Best practices for writing Dockerfiles . (source: https://github.com/docker/labs/tree/master/beginner ) Now that you know how to run docker container and create Dockerfiles let\u2019s move on to the practical part.","title":"TD part 01 - Docker"},{"location":"ch1-discover-docker-td/#discover-docker","text":"Check Checkpoint: do a commit and call us to check your results (don\u2019t stay blocked on a checkpoint if we are busy, we can check \u2154 checkpoints at the same time) Question Point to document/report Tip Interesting information","title":"Discover Docker"},{"location":"ch1-discover-docker-td/#setup","text":"","title":"Setup"},{"location":"ch1-discover-docker-td/#prerequisites","text":"There are no specific skills needed for this tutorial beyond a basic comfort with the command line and using a text editor. Prior experience in developing web applications will be helpful but is not required. As you proceed further along the tutorial, we'll make use of https://cloud.docker.com/.","title":"Prerequisites"},{"location":"ch1-discover-docker-td/#setting-up-your-computer","text":"Getting all the tooling setup on your computer can be a daunting task, but getting Docker up and running on your favorite OS has become very easy. The getting started guide on Docker has detailed instructions for setting up Docker on Mac , Linux and Windows If you're using Docker for Windows make sure you have shared your drive. Important note If you're using an older version of Windows or MacOS you may need to use Docker Machine instead. All commands work in either bash or Powershell on Windows Once you are done installing Docker, test your Docker installation by running the following: docker run hello-world Unable to find image 'hello-world:latest' locally latest: Pulling from library/hello-world 03f4658f8b78: Pull complete a3ed95caeb02: Pull complete Digest: sha256:8be990ef2aeb16dbcb9271ddfe2610fa6658d13f6dfb8bc72074cc1ca36966a7 Status: Downloaded newer image for hello-world:latest Hello from Docker. ... This message shows that your installation appears to be working correctly.","title":"Setting up your computer"},{"location":"ch1-discover-docker-td/#running-your-first-container","text":"Now that you have everything setup, it's time to get our hands dirty. In this section, you are going to run an Alpine Linux container (a lightweight linux distribution) on your system and get a taste of the docker run command. To get started, let's run the following in our terminal: docker pull alpine Note Depending on how you've installed docker on your system, you might see a permission denied error after running the above command. Try the commands from the Getting Started tutorial to verify your installation . If you're on Linux, you may need to prefix your docker commands with sudo . Alternatively you can create a docker group to get rid of this issue. The pull command fetches the alpine image from the Docker registry and saves it in our system. You can use the docker images command to see a list of all images on your system. docker images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE alpine latest c51f86c28340 4 weeks ago 1 .109 MB hello-world latest 690ed74de00f 5 months ago 960 B","title":"Running your first container"},{"location":"ch1-discover-docker-td/#11-docker-run","text":"Great! Let's now run a Docker container based on this image. To do that you are going to use the docker run command. docker run alpine ls -l total 48 drwxr-xr-x 2 root root 4096 Mar 2 16:20 bin drwxr-xr-x 5 root root 360 Mar 18 09:47 dev drwxr-xr-x 13 root root 4096 Mar 18 09:47 etc drwxr-xr-x 2 root root 4096 Mar 2 16:20 home drwxr-xr-x 5 root root 4096 Mar 2 16:20 lib ...... ...... What happened? Behind the scenes, a lot of stuff happened. When you call run : 1. The Docker client contacts the Docker daemon. The Docker daemon checks local store if the image (alpine in this case) is available locally, and if not, downloads it from Docker Store. (Since we have issued docker pull alpine before, the download step is not necessary) The Docker daemon creates the container and then runs a command in that container. The Docker daemon streams the output of the command to the Docker client When you run docker run alpine , you provided a command ( ls -l ), so Docker started the command specified and you saw the listing. Let's try something more exciting. docker run alpine echo \"hello from alpine\" hello from alpine OK, that's some actual output. In this case, the Docker client dutifully ran the echo command in our alpine container and then exited it. If you've noticed, all of that happened pretty quickly. Imagine booting up a virtual machine, running a command and then killing it. Now you know why they say containers are fast! Try another command. docker run alpine /bin/sh Wait, nothing happened! Is that a bug? Well, no. These interactive shells will exit after running any scripted commands, unless they are run in an interactive terminal - so for this example to not exit, you need to docker run -it alpine /bin/sh . You are now inside the container shell and you can try out a few commands like ls -l , uname -a and others. Exit out of the container by giving the exit command. Ok, now it's time to see the docker ps command. The docker ps command shows you all containers that are currently running. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES Since no containers are running, you see a blank line. Let's try a more useful variant: docker ps -a docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 36171a5da744 alpine \"/bin/sh\" 5 minutes ago Exited ( 0 ) 2 minutes ago fervent_newton a6a9d46d0b2f alpine \"echo 'hello from alp\" 6 minutes ago Exited ( 0 ) 6 minutes ago lonely_kilby ff0a5c3750b9 alpine \"ls -l\" 8 minutes ago Exited ( 0 ) 8 minutes ago elated_ramanujan c317d0a9e3d2 hello-world \"/hello\" 34 seconds ago Exited ( 0 ) 12 minutes ago stupefied_mcclintock What you see above is a list of all containers that you ran. Notice that the STATUS column shows that these containers exited a few minutes ago. You're probably wondering if there is a way to run more than just one command in a container. Let's try that now: docker run -it alpine /bin/sh / # ls bin dev etc home lib linuxrc media mnt proc root run sbin sys tmp usr var / # uname -a Linux 97916e8cb5dc 4.4.27-moby #1 SMP Wed Oct 26 14:01:48 UTC 2016 x86_64 Linux Running the run command with the -it flags attaches us to an interactive tty in the container. Now you can run as many commands in the container as you want. Take some time to run your favorite commands. Tip run -it is a very useful command to debug at the lowest level a container. That concludes a whirlwind tour of the docker run command which would most likely be the command you'll use most often. It makes sense to spend some time getting comfortable with it. To find out more about run , use docker run --help to see a list of all flags it supports. As you proceed further, we'll see a few more variants of docker run.","title":"1.1 Docker Run"},{"location":"ch1-discover-docker-td/#12-terminology","text":"In the last section, you saw a lot of Docker-specific jargon which might be confusing to some. So before you go further, let's clarify some terminology that is used frequently in the Docker ecosystem. Images - The file system and configuration of our application which are used to create containers. To find out more about a Docker image, run docker inspect alpine . In the demo above, you used the docker pull command to download the alpine image. When you executed the command docker run hello-world , it also did a docker pull behind the scenes to download the hello-world image. Containers - Running instances of Docker images \u2014 containers run the actual applications. A container includes an application and all of its dependencies. It shares the kernel with other containers, and runs as an isolated process in user space on the host OS. You created a container using docker run which you did using the alpine image that you downloaded. A list of running containers can be seen using the docker ps command. Docker daemon - The background service running on the host that manages building, running and distributing Docker containers. Docker client - The command line tool that allows the user to interact with the Docker daemon. Docker Store - A registry of Docker images, where you can find trusted and enterprise ready containers, plugins, and Docker editions. You'll be using this later in this tutorial.","title":"1.2 Terminology"},{"location":"ch1-discover-docker-td/#20-webapps-with-docker","text":"Great! So you have now looked at docker run , played with a Docker container and also got the hang of some terminology. Armed with all this knowledge, you are now ready to get to the real stuff \u2014 deploying web applications with Docker.","title":"2.0 Webapps with Docker"},{"location":"ch1-discover-docker-td/#21-run-a-static-website-in-a-container","text":"Note Code for this section is in this repo in the static-site directory Let's start by taking baby-steps. First, we'll use Docker to run a static website in a container. The website is based on an existing image. We'll pull a Docker image from Docker Store, run the container, and see how easy it is to set up a web server. The image that you are going to use is a single-page website that was already created for this demo and is available on the Docker Store as dockersamples/static-site . You can download and run the image directly in one go using docker run as follows. docker run -d dockersamples/static-site Note The current version of this image doesn't run without the -d flag. The -d flag enables detached mode, which detaches the running container from the terminal/shell and returns your prompt after the container starts. We are debugging the problem with this image but for now, use -d even for this first example. Tip -d is a very useful option. So, what happens when you run this command? Since the image doesn't exist on your Docker host, the Docker daemon first fetches it from the registry and then runs it as a container. Now that the server is running, do you see the website? What port is it running on? And more importantly, how do you access the container directly from our host machine? Actually, you probably won't be able to answer any of these questions yet! \u263a In this case, the client didn't tell the Docker Engine to publish any of the ports, so you need to re-run the docker run command to add this instruction. Let's re-run the command with some new flags to publish ports and pass your name to the container to customize the message displayed. We'll use the -d option again to run the container in detached mode. First, stop the container that you have just launched. In order to do this, we need the container ID. Since we ran the container in detached mode, we don't have to launch another terminal to do this. Run docker ps to view the running containers. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES a7a0e504ca3e dockersamples/static-site \"/bin/sh -c 'cd /usr/\" 28 seconds ago Up 26 seconds 80 /tcp, 443 /tcp stupefied_mahavira Check out the CONTAINER ID column. You will need to use this CONTAINER ID value, a long sequence of characters, to identify the container you want to stop, and then to remove it. The example below provides the CONTAINER ID on our system; you should use the value that you see in your terminal. docker stop a7a0e504ca3e docker rm a7a0e504ca3e Note A cool feature is that you do not need to specify the entire CONTAINER ID . You can just specify a few starting characters and if it is unique among all the containers that you have launched, the Docker client will intelligently pick it up. Now, let's launch a container in detached mode as shown below: docker run --name static-site -e AUTHOR = \"Enter Your Name Here\" -d -P dockersamples/static-site e61d12292d69556eabe2a44c16cbd54486b2527e2ce4f95438e504afb7b02810 In the above command: -d will create a container with the process detached from our terminal -P will publish all the exposed container ports to random ports on the Docker host -e is how you pass environment variables to the container. --name allows you to specify a container name AUTHOR is the environment variable name and Your Name is the value that you can pass. Now you can see the ports by running the docker port command. docker port static-site 443 /tcp -> 0 .0.0.0:32772 80 /tcp -> 0 .0.0.0:32773 You can open your freshly created website on http://localhost:[YOUR_PORT_FOR 80/tcp] . For our example this is http://localhost:32773 . You can now open http://localhost:[YOUR_PORT_FOR 80/tcp] to see your site live! For our example, this is: http://192.168.99.100:32773 . You can also run a second webserver at the same time, specifying a custom host port mapping to the container's webserver. docker run --name static-site-2 -e AUTHOR = \"Enter Your Name Here\" -d -p 8888 :80 dockersamples/static-site To deploy this on a real server you would just need to install Docker, and run the above docker command (as in this case you can see the AUTHOR is Docker which we passed as an environment variable). Now that you've seen how to run a webserver inside a Docker container, how do you create your own Docker image? This is the question we'll explore in the next section. But first, let's stop and remove the containers since you won't be using them anymore. docker stop static-site docker rm static-site Let's use a shortcut to remove the second site: docker rm -f static-site-2 Tip rm -f is a very useful option Run docker ps to make sure the containers are gone. docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES","title":"2.1 Run a static website in a container"},{"location":"ch1-discover-docker-td/#22-docker-images","text":"In this section, let's dive deeper into what Docker images are. You will build your own image, use that image to run an application locally, and finally, push some of your own images to Docker Cloud. Docker images are the basis of containers. In the previous example, you pulled the dockersamples/static-site image from the. registry and asked the Docker client to run a container based on that image. To see the list of images that are available locally on your system, run the docker images command. docker images REPOSITORY TAG IMAGE ID CREATED SIZE dockersamples/static-site latest 92a386b6e686 2 hours ago 190 .5 MB nginx latest af4b3d7d5401 3 hours ago 190 .5 MB python 2 .7 1c32174fd534 14 hours ago 676 .8 MB postgres 9 .4 88d845ac7a88 14 hours ago 263 .6 MB containous/traefik latest 27b4e0c6b2fd 4 days ago 20 .75 MB node 0 .10 42426a5cba5f 6 days ago 633 .7 MB redis latest 4f5f397d4b7c 7 days ago 177 .5 MB mongo latest 467eb21035a8 7 days ago 309 .7 MB alpine 3 .3 70c557e50ed6 8 days ago 4 .794 MB java 7 21f6ce84e43c 8 days ago 587 .7 MB Above is a list of images that I've pulled from the registry and those I've created myself (we'll shortly see how). You will have a different list of images on your machine. The TAG refers to a particular snapshot of the image and the ID is the corresponding unique identifier for that image. For simplicity, you can think of an image akin to a git repository - images can be committed with changes and have multiple. versions. When you do not provide a specific version number, the client defaults to latest. For example you could pull a specific version of ubuntu image as follows: docker pull ubuntu:12.04 If you do not specify the version number of the image then, as mentioned, the Docker client will default to a version named latest . So for example, the docker pull command given below will pull an image named ubuntu:latest : docker pull ubuntu To get a new Docker image you can either get it from a registry (such as the Docker Store) or create your own. There are hundreds of thousands of images available on Docker Store . You can also search for images directly from the command line using docker search . An important distinction with regard to images is between base images and child images . Base images are images that have no parent images, usually images with an OS like ubuntu, alpine or debian. Child images are images that build on base images and add additional functionality. Another key concept is the idea of official images and user images. (Both of which can be base images or child images.) Official images are Docker sanctioned images. Docker, Inc. sponsors a dedicated team that is responsible for reviewing and publishing all Official Repositories content. This team works in collaboration with upstream software maintainers, security experts, and the broader Docker community. These are not prefixed by an organization or user name. In the list of images above, the python , node , alpine and nginx images are official (base) images. To find out more about them, check out the Official Images Documentation . User images are images created and shared by users like you. They build on base images and add additional functionality. Typically these are formatted as user/image-name . The user value in the image name is your Docker Store user or organization name.","title":"2.2 Docker Images"},{"location":"ch1-discover-docker-td/#23-create-your-first-image","text":"Now that you have a better understanding of images, it's time to create your own. Our main objective here is to create an image that sandboxes a small Flask application. The goal of this exercise is to create a Docker image which will run a Flask app. We'll do this by first pulling together the components for a random cat picture generator built with Python Flask, then dockerizing it by writing a Dockerfile . Finally, we'll build the image, and then run it.","title":"2.3 Create your first image"},{"location":"ch1-discover-docker-td/#231-create-a-python-flask-app-that-displays-random-cat-pix","text":"For the purposes of this workshop, we've created a fun little Python Flask app that displays a random cat .gif every time it is loaded - because, you know, who doesn't like cats? Start by creating a directory called flask-app where we'll create the following files: app.py requirements.txt templates/index.html Dockerfile Make sure to cd flask-app before you start creating the files, because you don't want to start adding a whole bunch of other random files to your image.","title":"2.3.1 Create a Python Flask app that displays random cat pix."},{"location":"ch1-discover-docker-td/#apppy","text":"Create the app.py with the following content: from flask import Flask , render_template import random app = Flask ( __name__ ) # list of cat images images = [ \"https://c.tenor.com/GTcT7HODLRgAAAAM/smiling-cat-creepy-cat.gif\" , \"https://media0.giphy.com/media/10dU7AN7xsi1I4/giphy.webp?cid=ecf05e47gk63rd81vzlot57qmebr7drtgf6a3khmzvjsdtu7&rid=giphy.webp&ct=g\" , \"https://media0.giphy.com/media/S6VGjvmFRu5Qk/giphy.webp?cid=ecf05e478yofpawrhffnnvb3sgjkos96vyfo5mtqhds35as6&rid=giphy.webp&ct=g\" , \"https://media3.giphy.com/media/JIX9t2j0ZTN9S/200w.webp?cid=ecf05e47gk63rd81vzlot57qmebr7drtgf6a3khmzvjsdtu7&rid=200w.webp&ct=g\" ] @app . route ( '/' ) def index (): url = random . choice ( images ) return render_template ( 'index.html' , url = url ) if __name__ == \"__main__\" : app . run ( host = \"0.0.0.0\" )","title":"app.py"},{"location":"ch1-discover-docker-td/#requirementstxt","text":"In order to install the Python modules required for our app, we need to create a file called requirements.txt and add the following line to that file: Flask==3.1.0","title":"requirements.txt"},{"location":"ch1-discover-docker-td/#templatesindexhtml","text":"Create a directory called templates and create an index.html file in that directory with the following content in it: < html > < head > < style type = \"text/css\" > body { background : black ; color : white ; } div . container { max-width : 500 px ; margin : 100 px auto ; border : 20 px solid white ; padding : 10 px ; text-align : center ; } h4 { text-transform : uppercase ; } </ style > </ head > < body > < div class = \"container\" > < h4 > Cat Gif of the day </ h4 > < img src = \"{{url}}\" /> < p >< small > Courtesy: < a href = \"http://www.buzzfeed.com/copyranter/the-best-cat-gif-post-in-the-history-of-cat-gifs\" > Buzzfeed </ a ></ small ></ p > </ div > </ body > </ html >","title":"templates/index.html"},{"location":"ch1-discover-docker-td/#232-write-a-dockerfile","text":"We want to create a Docker image with this web app. As mentioned above, all user images are based on a base image. Since our application is written in Python, we will build our own Python image based on Alpine . We'll do that using a Dockerfile. A Dockerfile is a text file that contains a list of commands that the Docker daemon calls while creating an image. The Dockerfile contains all the information that Docker needs to know to run the app \u2014 a base Docker image to run from, location of your project code, any dependencies it has, and what commands to run at start-up. It is a simple way to automate the image creation process. The best part is that the commands you write in a Dockerfile are almost identical to their equivalent Linux commands. This means you don't really have to learn new syntax to create your own Dockerfiles. 1 - Create a file called Dockerfile, and add content to it as described below. We'll start by specifying our base image, using the FROM keyword. We are using alpine:3.21.0, a lightweight Linux distribution that helps keep our container small and efficient: FROM alpine:3.21.0 2 - Next, we need to install Python 3, pip, and other system dependencies required for our application. The apk add command is used to install packages in Alpine Linux. We use --no-cache to prevent unnecessary image bloat. Add the following RUN command: RUN apk add --no-cache build-base libffi-dev openssl-dev py3-pip python3 3 - Now, we set the working directory inside the container. This ensures that all subsequent commands run within this directory: WORKDIR /usr/src/app 4 - To create an isolated Python environment, we set up a virtual environment inside our container. This helps prevent conflicts between system-wide and project-specific dependencies: RUN python3 -m venv venv 5 - To ensure that all commands within the container use the virtual environment by default, we modify the PATH environment variable: ENV PATH = \"/usr/src/app/venv/bin: $PATH \" 6 - Next, we copy the application's dependencies file (requirements.txt) into the container and install the necessary Python packages. We also upgrade pip to the latest version to ensure compatibility: COPY requirements.txt ./ RUN pip install --no-cache-dir --upgrade pip && pip install --no-cache-dir -r requirements.txt 7 - Copy the files you have created earlier into our image by using COPY command. COPY app.py ./ COPY templates/index.html ./templates/ 8 - Since our Flask application runs on port 5000, we specify that this port should be exposed. This does not automatically publish the port but serves as documentation and can be used by orchestration tools: EXPOSE 5000 9 - The last step is the command for running the application which is simply - python ./app.py . Use the CMD command to do that: CMD [ \"python\" , \"/usr/src/app/app.py\" ] The primary purpose of CMD is to tell the container which command it should run by default when it is started. 10 - Verify your Dockerfile. Our Dockerfile is now ready. This is how it looks: # our base image FROM alpine:3.21.0 # Install Python 3, pip, and system dependencies RUN apk add --no-cache build-base libffi-dev openssl-dev py3-pip python3 # Set the working directory WORKDIR /usr/src/app # Create and activate a virtual environment RUN python3 -m venv venv # Use the virtual environment for all commands ENV PATH = \"/usr/src/app/venv/bin: $PATH \" # Copy and install dependencies COPY requirements.txt ./ RUN pip install --no-cache-dir --upgrade pip && pip install --no-cache-dir -r requirements.txt # Copy application files COPY app.py ./ COPY templates/index.html ./templates/ # Expose the application port EXPOSE 5000 # Run the application inside the virtual environment CMD [ \"python\" , \"/usr/src/app/app.py\" ]","title":"2.3.2 Write a Dockerfile"},{"location":"ch1-discover-docker-td/#233-build-the-image","text":"Now that you have your Dockerfile , you can build your image. The docker build command does the heavy-lifting of creating a docker image from a Dockerfile . When you run the docker build command given below, make sure to replace <YOUR_USERNAME> with your username. This username should be the same one you created when registering on Docker Cloud . If you haven't done that yet, please go ahead and create an account. The docker build command is quite simple - it takes an optional tag name with the -t flag, and the location of the directory containing the Dockerfile - the . indicates the current directory: docker build -t <YOUR_USERNAME>/myfirstapp . If you don't have the alpine:3.21.0 image, the client will first pull the image and then create your image. Therefore, your output on running the command will look different from mine. If everything went well, your image should be ready! Run docker images and see if your image ( <YOUR_USERNAME>/myfirstapp ) shows.","title":"2.3.3 Build the image"},{"location":"ch1-discover-docker-td/#234-run-your-image","text":"The next step in this section is to run the image and see if it actually works. docker run -p 8888 :5000 --name myfirstapp YOUR_USERNAME/myfirstapp * Serving Flask app 'app' * Debug mode: off WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead. * Running on all addresses ( 0 .0.0.0 ) * Running on http://127.0.0.1:5000 * Running on http://172.17.0.2:5000 Press CTRL+C to quit Head over to http://localhost:8888 and your app should be live. Note If you are using Docker Machine, you may need to open up another terminal and determine the container ip address using docker-machine ip default . Hit the Refresh button in the web browser to see a few more cat images. Check Show us your running flask-app !","title":"2.3.4 Run your image"},{"location":"ch1-discover-docker-td/#234-dockerfile-commands-summary","text":"Here's a quick summary of the few basic commands we used in our Dockerfile. FROM starts the Dockerfile. It is a requirement that the Dockerfile must start with the FROM command. Images are created in layers, which means you can use another image as the base image for your own. The FROM command defines your base layer. As arguments, it takes the name of the image. Optionally, you can add the Docker Cloud username of the maintainer and image version, in the format username/imagename:version . RUN is used to build up the Image you're creating. For each RUN command, Docker will run the command then create a new layer of the image. This way you can roll back your image to previous states easily. The syntax for a RUN instruction is to place the full text of the shell command after the RUN (e.g., RUN mkdir /user/local/foo ). This will automatically run in a /bin/sh shell. You can define a different shell like this: RUN /bin/bash -c 'mkdir /user/local/foo ' COPY copies local files into the container. CMD defines the commands that will run on the Image at start-up. Unlike a RUN , this does not create a new layer for the Image, but simply runs the command. There can only be one CMD per a Dockerfile/Image. If you need to run multiple commands, the best way to do that is to have the CMD run a script. CMD requires that you tell it where to run the command, unlike RUN . So example CMD commands would be: CMD [ \"python\" , \"./app.py\" ] CMD [ \"/bin/bash\" , \"echo\" , \"Hello World\" ] EXPOSE creates a hint for users of an image which ports provide services. It is included in the information which can be retrieved via docker inspect <container-id> . Note The EXPOSE command does not actually make any ports accessible to the host! Instead, this requires publishing ports by means of the -p flag when using docker run . Note If you want to learn more about Dockerfiles, check out Best practices for writing Dockerfiles . (source: https://github.com/docker/labs/tree/master/beginner ) Now that you know how to run docker container and create Dockerfiles let\u2019s move on to the practical part.","title":"2.3.4 Dockerfile commands summary"},{"location":"ch1-discover-docker-tp/","text":"Discover Docker Check Checkpoint: do a commit and call us to check your results (don\u2019t stay blocked on a checkpoint if we are busy, we can check \u2154 checkpoints at the same time). Question Point to document/report. Tip Interesting information. Goals Good practice Do not forget to document what you do along the steps, the documentation provided will be evaluated as your report. Create an appropriate file structure, 1 folder per image. Target application 3-tiers application: HTTP server Backend API Database For each of those applications, we will follow the same process: choose the appropriate docker base image, create and configure this image, put our application specifics inside and at some point have it running. Our final goal is to have a 3-tier web API running. Base images HTTP server Backend API Database Database Basics We will use the image: postgres:17.2-alpine. Let\u2019s have a simple postgres server running, here is what would be a minimal Dockerfile: FROM postgres:17.2-alpine ENV POSTGRES_DB = db \\ POSTGRES_USER = usr \\ POSTGRES_PASSWORD = pwd Build this image and start a container properly. Your Postgres DB should be up and running. Check that everything is running smoothly with the docker command of your choice. Don\u2019t forget to name your docker image and container. Tip If you have difficulties go back to part 2.3.3 Build the image and 2.3.4 Run your image on TD01 - Docker ( TD 1 Discover Docker ). Re-run your database with adminer . Don't forget --network app-network to enable adminer/database communication. We use -\u2013network instead of -\u2013link because the latter is deprecated. Tip Don't forget to create your network docker network create app-network Also, does it seem right to have passwords written in plain text in a file? You may rather define those environment parameters when running the image using the flag -e . Question 1-1 For which reason is it better to run the container with a flag -e to give the environment variables rather than put them directly in the Dockerfile? It would be nice to have our database structure initialized with the docker image as well as some initial data. Any sql scripts found in /docker-entrypoint-initdb.d will be executed in alphabetical order, therefore let\u2019s add a couple scripts to our image: Tip Don't forget to restart the adminer: docker run \\ -p \"8090:8080\" \\ --net = app-network \\ --name = adminer \\ -d \\ adminer Init database 01-CreateScheme.sql CREATE TABLE public . departments ( id SERIAL PRIMARY KEY , name VARCHAR ( 20 ) NOT NULL ); CREATE TABLE public . students ( id SERIAL PRIMARY KEY , department_id INT NOT NULL REFERENCES departments ( id ), first_name VARCHAR ( 20 ) NOT NULL , last_name VARCHAR ( 20 ) NOT NULL ); 02-InsertData.sql INSERT INTO departments ( name ) VALUES ( 'IRC' ); INSERT INTO departments ( name ) VALUES ( 'ETI' ); INSERT INTO departments ( name ) VALUES ( 'CGP' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 1 , 'Eli' , 'Copter' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 2 , 'Emma' , 'Carena' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 2 , 'Jack' , 'Uzzi' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 3 , 'Aude' , 'Javel' ); Rebuild your image and check that your scripts have been executed at startup and that the data is present in your container. Tip When we talk about /docker-entrypoint-initdb.d it means inside the container, so you have to copy your directory's content and the container\u2019s directory. Persist data You may have noticed that if your database container gets destroyed then all your data is reset, a database must persist data durably. Use volumes to persist data on the host disk. -v /my/own/datadir:/var/lib/postgresql/data Check that data survives when your container gets destroyed. Link Docker volumes Question 1-2 Why do we need a volume to be attached to our postgres container? Question 1-3 Document your database container essentials: commands and Dockerfile. Backend API Basics For starters, we will simply run a Java hello-world class in our containers, only after will we be running a jar. In both cases, choose the proper image keeping in mind that we only need a Java runtime . Here is a complex Java Hello World implementation: Main.java public class Main { public static void main ( String [] args ) { System . out . println ( \"Hello World!\" ); } } 1- Compile with your target Java: javac Main.java . 2- Write dockerfile. FROM # TODO: Choose a java JRE # TODO: Add the compiled java (aka bytecode, aka .class) # TODO: Run the Java with: \u201cjava Main\u201d command. 3- Now, to launch app you have to do the same thing that Basic step 1. Here you have a first glimpse of your backend application. In the next step we will simply enrich the build (using maven instead of a minimalistic javac) and execute a jar instead of a simple .class. \u2192 If it\u2019s a success you must see \u201cHello Word\u201d in your console. Multistage build In the previous section we were building Java code on our machine to have it running on a docker container. Wouldn\u2019t it be great to have Docker handle the build as well? You probably noticed that the default openjdk docker images contain... Well... a JDK! Create a multistage build using the Multistage . Your Dockerfile should look like this: FROM eclipse-temurin:21-jdk-alpine # Build Main.java with JDK # TODO : in next steps (not now) FROM eclipse-temurin:21-jre-alpine # Copy resource from previous stage COPY --from = 0 /usr/src/Main.class . # Run java code with the JRE # TODO : in next steps (not now) Don\u2019t fill the Dockerfile now, we will have to do it in the next steps. Backend simple api We will deploy a Springboot application providing a simple API with a single greeting endpoint. Create your Springboot application on: Spring Initializer . Use the following config: Project: Maven Language: Java 21 Spring Boot: 3.4.5 Packaging: Jar Dependencies: Spring Web Generate the project and give it a simple GreetingController class: package fr.takima.training.simpleapi.controller ; import org.springframework.web.bind.annotation.* ; import java.util.concurrent.atomic.AtomicLong ; @RestController public class GreetingController { private static final String template = \"Hello, %s!\" ; private final AtomicLong counter = new AtomicLong (); @GetMapping ( \"/\" ) public Greeting greeting ( @RequestParam ( value = \"name\" , defaultValue = \"World\" ) String name ) { return new Greeting ( counter . incrementAndGet (), String . format ( template , name )); } record Greeting ( long id , String content ) {} } You can now build and start your application, of course you will need maven and a jdk-21. How convenient would it be to have a virtual container to build and run our simplistic API? Oh wait, we have docker, here is how you could build and run your application with Docker: # Build stage FROM eclipse-temurin:21-jdk-alpine AS myapp-build ENV MYAPP_HOME = /opt/myapp WORKDIR $MYAPP_HOME RUN apk add --no-cache maven COPY pom.xml . COPY src ./src RUN mvn package -DskipTests # Run stage FROM eclipse-temurin:21-jre-alpine ENV MYAPP_HOME = /opt/myapp WORKDIR $MYAPP_HOME COPY --from = myapp-build $MYAPP_HOME /target/*.jar $MYAPP_HOME /myapp.jar ENTRYPOINT [ \"java\" , \"-jar\" , \"myapp.jar\" ] Question 1-4 Why do we need a multistage build? And explain each step of this dockerfile. Check A working Springboot application with a simple HelloWorld endpoint. Did you notice that maven downloads all libraries on every image build? You can contribute to saving the planet caching libraries when maven pom file has not been changed by running the goal: mvn dependency:go-offline . Backend API Let\u2019s now build and run the backend API connected to the database. You can get the zipped source code here: simple-api . You can replace only your src directory and the pom.xml file with the ones available in the repository. Adjust the configuration in simple-api/src/main/resources/application.yml (this is the application configuration). How to access the database container from your backend application? Use the deprecated --link or create a docker network . Once everything is properly bound, you should be able to access your application API, for example on: /departments/IRC/students . [ { \"id\" : 1 , \"firstname\" : \"Eli\" , \"lastname\" : \"Copter\" , \"department\" : { \"id\" : 1 , \"name\" : \"IRC\" } } ] Explore your API other endpoints, have a look at the controllers in the source code. Check A simple web API on top of your database. Http server Basics Choose an appropriate base image. Create a simple landing page: index.html and put it inside your container. It should be enough for now, start your container and check that everything is working as expected. Here are commands that you may want to try to do so: docker stats docker inspect docker logs Link Httpd Getting Started Configuration You are using the default apache configuration, and it will be enough for now, you use yours by copying it in your image. Use docker exec to retrieve this default configuration from your running container /usr/local/apache2/conf/httpd.conf . Note You can also use docker cp . Reverse proxy We will configure the http server as a simple reverse proxy server in front of our application, this server could be used to deliver a front-end application, to configure SSL or to handle load balancing. So this can be quite useful even though in our case we will keep things simple. Here is the documentation: Reverse Proxy . Add the following to the configuration, and you should be all set: <VirtualHost *:80> ProxyPreserveHost On ProxyPass / http://YOUR_BACKEND_LINK:8080/ ProxyPassReverse / http://YOUR_BACKEND_LINK:8080/ </VirtualHost> LoadModule proxy_module modules/mod_proxy.so LoadModule proxy_http_module modules/mod_proxy_http.so Question 1-5 Why do we need a reverse proxy? Check Checkpoint: a working application through a reverse proxy. Link application Docker-compose 1- Install docker-compose if the docker compose command does not work . You may have noticed that this can be quite painful to orchestrate manually the start, stop and rebuild of our containers. Thankfully, a useful tool called docker-compose comes in handy in those situations. 2- Let\u2019s create a docker-compose.yml file with the following structure to define and drive our containers: services : backend : build : #TODO networks : #TODO depends_on : #TODO database : build : #TODO networks : #TODO httpd : build : #TODO ports : #TODO networks : #TODO depends_on : #TODO networks : #TODO volumes : #TODO The docker-compose will handle the three containers for us. The file above is a basic example of structure, you need to add more parameters and think about the cleanest and most optimized approach like you would do in a company (for example: env variables, volumes, restart policies and processes segregation). Once your containers are orchestrated as services by docker-compose you should have a perfectly running application, make sure you can access your API on localhost . Note The ports of both your backend and database should not be opened to your host machine. Question 1-6 Why is docker-compose so important? Question 1-7 Document docker-compose most important commands. Question 1-8 Document your docker-compose file. Check A working 3-tier application running with docker-compose. Publish Your docker images are stored locally, let\u2019s publish them, so they can be used by other team members or on other machines. You will need a Docker Hub account. 1- Connect to your freshly created account with docker login . 2- Tag your image. For now, we have been only using the latest tag, now that we want to publish it, let\u2019s add some meaningful version information to our images. docker tag my-database USERNAME/my-database:1.0 3- Then push your image to dockerhub: docker push USERNAME/my-database:1.0 Dockerhub is not the only docker image registry, and you can also self-host your images (this is obviously the choice of most companies). Once you publish your images to dockerhub, you will see them in your account: having some documentation for your image would be quite useful if you want to use those later. Question 1-9 Document your publication commands and published images in dockerhub. Question 1-10 Why do we put our images into an online repo? \u00a9 Takima 2025","title":"TP part 01 - Docker"},{"location":"ch1-discover-docker-tp/#discover-docker","text":"Check Checkpoint: do a commit and call us to check your results (don\u2019t stay blocked on a checkpoint if we are busy, we can check \u2154 checkpoints at the same time). Question Point to document/report. Tip Interesting information.","title":"Discover Docker"},{"location":"ch1-discover-docker-tp/#goals","text":"","title":"Goals"},{"location":"ch1-discover-docker-tp/#good-practice","text":"Do not forget to document what you do along the steps, the documentation provided will be evaluated as your report. Create an appropriate file structure, 1 folder per image.","title":"Good practice"},{"location":"ch1-discover-docker-tp/#target-application","text":"3-tiers application: HTTP server Backend API Database For each of those applications, we will follow the same process: choose the appropriate docker base image, create and configure this image, put our application specifics inside and at some point have it running. Our final goal is to have a 3-tier web API running.","title":"Target application"},{"location":"ch1-discover-docker-tp/#base-images","text":"HTTP server Backend API Database","title":"Base images"},{"location":"ch1-discover-docker-tp/#database","text":"","title":"Database"},{"location":"ch1-discover-docker-tp/#basics","text":"We will use the image: postgres:17.2-alpine. Let\u2019s have a simple postgres server running, here is what would be a minimal Dockerfile: FROM postgres:17.2-alpine ENV POSTGRES_DB = db \\ POSTGRES_USER = usr \\ POSTGRES_PASSWORD = pwd Build this image and start a container properly. Your Postgres DB should be up and running. Check that everything is running smoothly with the docker command of your choice. Don\u2019t forget to name your docker image and container. Tip If you have difficulties go back to part 2.3.3 Build the image and 2.3.4 Run your image on TD01 - Docker ( TD 1 Discover Docker ). Re-run your database with adminer . Don't forget --network app-network to enable adminer/database communication. We use -\u2013network instead of -\u2013link because the latter is deprecated. Tip Don't forget to create your network docker network create app-network Also, does it seem right to have passwords written in plain text in a file? You may rather define those environment parameters when running the image using the flag -e . Question 1-1 For which reason is it better to run the container with a flag -e to give the environment variables rather than put them directly in the Dockerfile? It would be nice to have our database structure initialized with the docker image as well as some initial data. Any sql scripts found in /docker-entrypoint-initdb.d will be executed in alphabetical order, therefore let\u2019s add a couple scripts to our image: Tip Don't forget to restart the adminer: docker run \\ -p \"8090:8080\" \\ --net = app-network \\ --name = adminer \\ -d \\ adminer","title":"Basics"},{"location":"ch1-discover-docker-tp/#init-database","text":"01-CreateScheme.sql CREATE TABLE public . departments ( id SERIAL PRIMARY KEY , name VARCHAR ( 20 ) NOT NULL ); CREATE TABLE public . students ( id SERIAL PRIMARY KEY , department_id INT NOT NULL REFERENCES departments ( id ), first_name VARCHAR ( 20 ) NOT NULL , last_name VARCHAR ( 20 ) NOT NULL ); 02-InsertData.sql INSERT INTO departments ( name ) VALUES ( 'IRC' ); INSERT INTO departments ( name ) VALUES ( 'ETI' ); INSERT INTO departments ( name ) VALUES ( 'CGP' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 1 , 'Eli' , 'Copter' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 2 , 'Emma' , 'Carena' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 2 , 'Jack' , 'Uzzi' ); INSERT INTO students ( department_id , first_name , last_name ) VALUES ( 3 , 'Aude' , 'Javel' ); Rebuild your image and check that your scripts have been executed at startup and that the data is present in your container. Tip When we talk about /docker-entrypoint-initdb.d it means inside the container, so you have to copy your directory's content and the container\u2019s directory.","title":"Init database"},{"location":"ch1-discover-docker-tp/#persist-data","text":"You may have noticed that if your database container gets destroyed then all your data is reset, a database must persist data durably. Use volumes to persist data on the host disk. -v /my/own/datadir:/var/lib/postgresql/data Check that data survives when your container gets destroyed. Link Docker volumes Question 1-2 Why do we need a volume to be attached to our postgres container? Question 1-3 Document your database container essentials: commands and Dockerfile.","title":"Persist data"},{"location":"ch1-discover-docker-tp/#backend-api","text":"","title":"Backend API"},{"location":"ch1-discover-docker-tp/#basics_1","text":"For starters, we will simply run a Java hello-world class in our containers, only after will we be running a jar. In both cases, choose the proper image keeping in mind that we only need a Java runtime . Here is a complex Java Hello World implementation: Main.java public class Main { public static void main ( String [] args ) { System . out . println ( \"Hello World!\" ); } } 1- Compile with your target Java: javac Main.java . 2- Write dockerfile. FROM # TODO: Choose a java JRE # TODO: Add the compiled java (aka bytecode, aka .class) # TODO: Run the Java with: \u201cjava Main\u201d command. 3- Now, to launch app you have to do the same thing that Basic step 1. Here you have a first glimpse of your backend application. In the next step we will simply enrich the build (using maven instead of a minimalistic javac) and execute a jar instead of a simple .class. \u2192 If it\u2019s a success you must see \u201cHello Word\u201d in your console.","title":"Basics"},{"location":"ch1-discover-docker-tp/#multistage-build","text":"In the previous section we were building Java code on our machine to have it running on a docker container. Wouldn\u2019t it be great to have Docker handle the build as well? You probably noticed that the default openjdk docker images contain... Well... a JDK! Create a multistage build using the Multistage . Your Dockerfile should look like this: FROM eclipse-temurin:21-jdk-alpine # Build Main.java with JDK # TODO : in next steps (not now) FROM eclipse-temurin:21-jre-alpine # Copy resource from previous stage COPY --from = 0 /usr/src/Main.class . # Run java code with the JRE # TODO : in next steps (not now) Don\u2019t fill the Dockerfile now, we will have to do it in the next steps.","title":"Multistage build"},{"location":"ch1-discover-docker-tp/#backend-simple-api","text":"We will deploy a Springboot application providing a simple API with a single greeting endpoint. Create your Springboot application on: Spring Initializer . Use the following config: Project: Maven Language: Java 21 Spring Boot: 3.4.5 Packaging: Jar Dependencies: Spring Web Generate the project and give it a simple GreetingController class: package fr.takima.training.simpleapi.controller ; import org.springframework.web.bind.annotation.* ; import java.util.concurrent.atomic.AtomicLong ; @RestController public class GreetingController { private static final String template = \"Hello, %s!\" ; private final AtomicLong counter = new AtomicLong (); @GetMapping ( \"/\" ) public Greeting greeting ( @RequestParam ( value = \"name\" , defaultValue = \"World\" ) String name ) { return new Greeting ( counter . incrementAndGet (), String . format ( template , name )); } record Greeting ( long id , String content ) {} } You can now build and start your application, of course you will need maven and a jdk-21. How convenient would it be to have a virtual container to build and run our simplistic API? Oh wait, we have docker, here is how you could build and run your application with Docker: # Build stage FROM eclipse-temurin:21-jdk-alpine AS myapp-build ENV MYAPP_HOME = /opt/myapp WORKDIR $MYAPP_HOME RUN apk add --no-cache maven COPY pom.xml . COPY src ./src RUN mvn package -DskipTests # Run stage FROM eclipse-temurin:21-jre-alpine ENV MYAPP_HOME = /opt/myapp WORKDIR $MYAPP_HOME COPY --from = myapp-build $MYAPP_HOME /target/*.jar $MYAPP_HOME /myapp.jar ENTRYPOINT [ \"java\" , \"-jar\" , \"myapp.jar\" ] Question 1-4 Why do we need a multistage build? And explain each step of this dockerfile. Check A working Springboot application with a simple HelloWorld endpoint. Did you notice that maven downloads all libraries on every image build? You can contribute to saving the planet caching libraries when maven pom file has not been changed by running the goal: mvn dependency:go-offline .","title":"Backend simple api"},{"location":"ch1-discover-docker-tp/#backend-api_1","text":"Let\u2019s now build and run the backend API connected to the database. You can get the zipped source code here: simple-api . You can replace only your src directory and the pom.xml file with the ones available in the repository. Adjust the configuration in simple-api/src/main/resources/application.yml (this is the application configuration). How to access the database container from your backend application? Use the deprecated --link or create a docker network . Once everything is properly bound, you should be able to access your application API, for example on: /departments/IRC/students . [ { \"id\" : 1 , \"firstname\" : \"Eli\" , \"lastname\" : \"Copter\" , \"department\" : { \"id\" : 1 , \"name\" : \"IRC\" } } ] Explore your API other endpoints, have a look at the controllers in the source code. Check A simple web API on top of your database.","title":"Backend API"},{"location":"ch1-discover-docker-tp/#http-server","text":"","title":"Http server"},{"location":"ch1-discover-docker-tp/#basics_2","text":"","title":"Basics"},{"location":"ch1-discover-docker-tp/#choose-an-appropriate-base-image","text":"Create a simple landing page: index.html and put it inside your container. It should be enough for now, start your container and check that everything is working as expected. Here are commands that you may want to try to do so: docker stats docker inspect docker logs Link Httpd Getting Started","title":"Choose an appropriate base image."},{"location":"ch1-discover-docker-tp/#configuration","text":"You are using the default apache configuration, and it will be enough for now, you use yours by copying it in your image. Use docker exec to retrieve this default configuration from your running container /usr/local/apache2/conf/httpd.conf . Note You can also use docker cp .","title":"Configuration"},{"location":"ch1-discover-docker-tp/#reverse-proxy","text":"We will configure the http server as a simple reverse proxy server in front of our application, this server could be used to deliver a front-end application, to configure SSL or to handle load balancing. So this can be quite useful even though in our case we will keep things simple. Here is the documentation: Reverse Proxy . Add the following to the configuration, and you should be all set: <VirtualHost *:80> ProxyPreserveHost On ProxyPass / http://YOUR_BACKEND_LINK:8080/ ProxyPassReverse / http://YOUR_BACKEND_LINK:8080/ </VirtualHost> LoadModule proxy_module modules/mod_proxy.so LoadModule proxy_http_module modules/mod_proxy_http.so Question 1-5 Why do we need a reverse proxy? Check Checkpoint: a working application through a reverse proxy.","title":"Reverse proxy"},{"location":"ch1-discover-docker-tp/#link-application","text":"","title":"Link application"},{"location":"ch1-discover-docker-tp/#docker-compose","text":"1- Install docker-compose if the docker compose command does not work . You may have noticed that this can be quite painful to orchestrate manually the start, stop and rebuild of our containers. Thankfully, a useful tool called docker-compose comes in handy in those situations. 2- Let\u2019s create a docker-compose.yml file with the following structure to define and drive our containers: services : backend : build : #TODO networks : #TODO depends_on : #TODO database : build : #TODO networks : #TODO httpd : build : #TODO ports : #TODO networks : #TODO depends_on : #TODO networks : #TODO volumes : #TODO The docker-compose will handle the three containers for us. The file above is a basic example of structure, you need to add more parameters and think about the cleanest and most optimized approach like you would do in a company (for example: env variables, volumes, restart policies and processes segregation). Once your containers are orchestrated as services by docker-compose you should have a perfectly running application, make sure you can access your API on localhost . Note The ports of both your backend and database should not be opened to your host machine. Question 1-6 Why is docker-compose so important? Question 1-7 Document docker-compose most important commands. Question 1-8 Document your docker-compose file. Check A working 3-tier application running with docker-compose.","title":"Docker-compose"},{"location":"ch1-discover-docker-tp/#publish","text":"Your docker images are stored locally, let\u2019s publish them, so they can be used by other team members or on other machines. You will need a Docker Hub account. 1- Connect to your freshly created account with docker login . 2- Tag your image. For now, we have been only using the latest tag, now that we want to publish it, let\u2019s add some meaningful version information to our images. docker tag my-database USERNAME/my-database:1.0 3- Then push your image to dockerhub: docker push USERNAME/my-database:1.0 Dockerhub is not the only docker image registry, and you can also self-host your images (this is obviously the choice of most companies). Once you publish your images to dockerhub, you will see them in your account: having some documentation for your image would be quite useful if you want to use those later. Question 1-9 Document your publication commands and published images in dockerhub. Question 1-10 Why do we put our images into an online repo? \u00a9 Takima 2025","title":"Publish"},{"location":"cheatsheet/","text":"Cheatsheet Docker & docker-compose","title":"Cheatsheet"},{"location":"cheatsheet/#cheatsheet","text":"","title":"Cheatsheet"},{"location":"cheatsheet/#docker-docker-compose","text":"","title":"Docker &amp; docker-compose"}]}
\ No newline at end of file
diff --git a/public/sitemap.xml b/public/sitemap.xml
index 6e8df39abef41ce136fb7dd3776f95dda2837b0b..4a753f09085545b9ed448ed16235fbae06fb2c8e 100644
--- a/public/sitemap.xml
+++ b/public/sitemap.xml
@@ -2,22 +2,22 @@
 <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
     <url>
          <loc>None</loc>
-         <lastmod>2025-05-18</lastmod>
+         <lastmod>2025-05-19</lastmod>
          <changefreq>daily</changefreq>
     </url>
     <url>
          <loc>None</loc>
-         <lastmod>2025-05-18</lastmod>
+         <lastmod>2025-05-19</lastmod>
          <changefreq>daily</changefreq>
     </url>
     <url>
          <loc>None</loc>
-         <lastmod>2025-05-18</lastmod>
+         <lastmod>2025-05-19</lastmod>
          <changefreq>daily</changefreq>
     </url>
     <url>
          <loc>None</loc>
-         <lastmod>2025-05-18</lastmod>
+         <lastmod>2025-05-19</lastmod>
          <changefreq>daily</changefreq>
     </url>
 </urlset>
\ No newline at end of file
diff --git a/public/sitemap.xml.gz b/public/sitemap.xml.gz
index e393be92c1c8f566ead102314336a5bc8ea454fc..828a583e93d783b5b1fcd6fd03009bf1d51b8771 100644
Binary files a/public/sitemap.xml.gz and b/public/sitemap.xml.gz differ