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Tutorial: Prepare an application for Azure Kubernetes Service (AKS)

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In this tutorial, part one of seven, you prepare a multi-container application to use in Kubernetes. You use existing development tools like Docker Compose to locally build and test the application. You learn how to:

  • Clone a sample application source from GitHub
  • Create a container image from the sample application source
  • Test the multi-container application in a local Docker environment

Once completed, the following application runs in your local development environment:

Screenshot showing the container image Azure Voting App running locally opened in a local web browser

In later tutorials, you upload the container image to an Azure Container Registry (ACR), and then deploy it into an AKS cluster.

Before you begin

This tutorial assumes a basic understanding of core Docker concepts such as containers, container images, and docker commands. For a primer on container basics, see Get started with Docker.

To complete this tutorial, you need a local Docker development environment running Linux containers. Docker provides packages that configure Docker on a Mac, Windows, or Linux system.

Note

Azure Cloud Shell does not include the Docker components required to complete every step in these tutorials. Therefore, we recommend using a full Docker development environment.

Get application code

The sample application used in this tutorial is a basic voting app consisting of a front-end web component and a back-end Redis instance. The web component is packaged into a custom container image. The Redis instance uses an unmodified image from Docker Hub.

Use git to clone the sample application to your development environment.

git clone https://github.com/Azure-Samples/azure-voting-app-redis.git

Change into the cloned directory.

cd azure-voting-app-redis

The directory contains the application source code, a pre-created Docker compose file, and a Kubernetes manifest file. These files are used throughout the tutorial set. The contents and structure of the directory are as follows:

azure-voting-app-redis
│   azure-vote-all-in-one-redis.yaml
│   docker-compose.yaml
│   LICENSE
│   README.md
│
├───azure-vote
│   │   app_init.supervisord.conf
│   │   Dockerfile
│   │   Dockerfile-for-app-service
│   │   sshd_config
│   │
│   └───azure-vote
│       │   config_file.cfg
│       │   main.py
│       │
│       ├───static
│       │       default.css
│       │
│       └───templates
│               index.html
│
└───jenkins-tutorial
        config-jenkins.sh
        deploy-jenkins-vm.sh

Create container images

Docker Compose can be used to automate building container images and the deployment of multi-container applications.

The following command uses the sample docker-compose.yaml file to create the container image, download the Redis image, and start the application.

docker compose up -d

When completed, use the docker images command to see the created images. Two images are downloaded or created. The azure-vote-front image contains the front-end application. The redis image is used to start a Redis instance.

$ docker images
REPOSITORY                                     TAG       IMAGE ID       CREATED       SIZE
mcr.microsoft.com/oss/bitnami/redis            6.0.8     3a54a920bb6c   2 years ago   103MB
mcr.microsoft.com/azuredocs/azure-vote-front   v1        4d4d08c25677   5 years ago   935MB

Run the docker ps command to see the running containers.

$ docker ps

CONTAINER ID        IMAGE                                             COMMAND                  CREATED             STATUS              PORTS                           NAMES
d10e5244f237        mcr.microsoft.com/azuredocs/azure-vote-front:v1   "/entrypoint.sh /sta…"   3 minutes ago       Up 3 minutes        443/tcp, 0.0.0.0:8080->80/tcp   azure-vote-front
21574cb38c1f        mcr.microsoft.com/oss/bitnami/redis:6.0.8         "/opt/bitnami/script…"   3 minutes ago       Up 3 minutes        0.0.0.0:6379->6379/tcp          azure-vote-back

Test application locally

To see your running application, navigate to http://localhost:8080 in a local web browser. The sample application loads, as shown in the following example:

Screenshot showing the container image Azure Voting App running locally opened in a local web browser

Clean up resources

Now that the application's functionality has been validated, the running containers can be stopped and removed. Do not delete the container images - in the next tutorial, you'll upload the azure-vote-front image to an ACR instance.

To stop and remove the container instances and resources, use the docker-compose down command.

docker compose down

When the local application has been removed, you have a Docker image that contains the Azure Vote application, azure-vote-front, to use in the next tutorial.

Next steps

In this tutorial, you created a sample application, created container images for the application, and then tested the application. You learned how to:

  • Clone a sample application source from GitHub
  • Create a container image from the sample application source
  • Test the multi-container application in a local Docker environment

In the next tutorial, you'll learn how to store container images in an ACR.

Push images to Azure Container Registry