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Introduction​

This guide walks you through migrating an application from Heroku to Azure Kubernetes Service (AKS) using Massdriver, with an emphasis on using private network access to enhance security. We’ll use Azure’s services, and Massdriver will handle most of the infrastructure setup and orchestration.

Prerequisites​

Before starting, ensure you have the following:

Step 1: Create a Dockerfile​

It’s hard to provide a general guide on how to dockerize a Heroku app, as it depends on the app's structure and dependencies. However, here are some general tips that might help you:

  1. Use docker init in your app directory to generate a custom Dockerfile for your app.
  2. Use a .dockerignore file to exclude unnecessary files and directories from the Docker image.
  3. Use a build cache to speed up the build process.
  4. Build and test your Docker image locally before pushing it to a registry.

For a detailed video on getting started with Dockerizing an application, check out:

Step 2: Build and Test the Docker Image​

  1. Set up some environment variables to make the process easier:

    imageName="<your-image-name>" # e.g. my-app
    namespace="<your-namespace>" # e.g. my-image-namespace
    location="westus" # set this to your preferred Azure region
    mdArtifactId="<your artifact id>" # https://docs.massdriver.cloud/concepts/artifacts#artifact-id

  2. Build the Docker image:

    docker build -t $imageName .

  3. Run the Docker image locally to test it:

    docker run -p 8080:8080 $imageName

  4. Browse to http://localhost:8080 to see your app running.

Step 3: Create a Massdriver application bundle​

  1. Setup the Mass CLI environment variables noted here.

  2. Generate a new application template:

    • Run the following command and follow the prompts:
    mass bundle new

  3. Add your environment variables to the massdriver.yaml file:

    • Review the example below of how to configure environment variables in the massdriver.yaml file:
    app:
      envs:
         LOG_LEVEL: .params.configuration.log_level
         MONGO_DSN: .connections.mongo_authentication.data.authentication.username + ":" + .connections.mongo_authentication.data.authentication.password + "@" + .connections.mongo_authentication.data.authentication.hostname + ":" + (.connections.mongo_authentication.data.authentication.port|tostring)
      policies:
         - .connections.storage_account.data.security.iam.read_write
      secrets:
         OPENAI_API_KEY:
           required: true
           title: OpenAI API Key
           description: The API key for OpenAI that gives me sketchy life advice

  4. Publish your application bundle to Massdriver:

    mass bundle publish

  5. View your application bundle in Massdriver:

    • Browse to https://app.massdriver.cloud and log in.
    • In the Bundle Catalog, search for your application bundle.
    • Drag it out to the canvas to start configuring your application.
    • If you want to implement DNS, be sure add DNS and configure it based on your domain registrar, then enable DNS for AKS first.
    • Don't deploy yet!!

Step 4: Push the Docker Image to Azure Container Registry​

  1. Build and push your image to ACR:

    mass image push $namespace/$imageName --region $location --artifact $mdArtifactId --tag latest

  2. Copy output from the previous command and paste in Repository field in your application bundle configuration in Massdriver.

  3. Set the Tag field to latest.

Step 5: Deploy and Test​

  1. Deploy your application bundle in Massdriver:

    • Click the Deploy button in the bottom of your bundle configuration.

  2. Access your application:

    • Set up kubectl and kubeconfig to access your AKS cluster by following this guide.
    • Run the following commands to view your application's status:
    kubectl get pods
    kubectl describe pod <pod-name>
    kubectl logs <pod-name>