Exercise - Build the application image

  • 10 minutes

In this unit, you create your GitHub Actions staging pipeline by building the application image and pushing it to Azure Container Registry.

The following image shows the CI/CD pipeline you designed:

Diagram that shows the procession from triggers, through three build steps, to the deploy steps in a pipeline.

In this exercise, you create the staging pipeline by doing the following steps:

  • Create the GitHub Actions workflow.
  • Create the on push trigger.
  • Build and push the application image.
  • Set secrets.
  • Run the job.

Create the GitHub Actions workflow

GitHub workflows are divided into jobs, and jobs are divided into steps. Each step can have multiple commands and use multiple actions to execute.

To start building your pipeline, go to your fork of the sample repository in the GitHub website.

  1. Select the Actions tab.

  2. Select the link to set up a workflow yourself.

    Screenshot that shows the Get started with GitHub Actions page on the GitHub website.

    At this point, the pipeline is just a blank file in the .github/workflows directory in your repository. GitHub provides the prebuilt components that you need to build most of the pipelines. To get started, copy and paste the following code into the Edit new file pane:

    # This is a basic workflow to help you get started with Actions

name: CI

# Controls when the action will run. Triggers the workflow on push or pull request
# events but only for the main branch
on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

# A workflow run is made up of one or more jobs that can run sequentially or in parallel
jobs:
  # This workflow contains a single job called "build"
  build:
    # The type of runner that the job will run on
    runs-on: ubuntu-latest

    # Steps represent a sequence of tasks that will be executed as part of the job
    steps:
      # Checks out your repository under $GITHUB_WORKSPACE, so your job can access it
      - uses: actions/checkout@v2

      # Runs a single command using the runners shell
      - name: Run a one-line script
        run: echo Hello, world!

      # Runs a set of commands using the runners shell
      - name: Run a multi-line script
        run: |
          echo Add other actions to build,
          echo test, and deploy your project.

  3. Above the Edit new file pane, rename the file from main.yml to build-staging.yml.

    Screenshot that shows an example file being edited in the Edit new file pane on the GitHub website.

  4. Change the name key from CI to Build and push the latest build to staging.

    # This is a basic workflow to help you get started with Actions

name: Build and push the latest build to staging

Modify the 'on' trigger

The basic workflow template comes with two triggers:

  • Any push to the main branch.
  • Any pull request on the main branch.

You don't need the pipeline to run on a pull request, so modify it to keep only the push trigger by changing the triggers in the on key. Remove the second trigger and leave only the push tags.

name: Build and push the latest build to staging

on:
  push:
    branches: [ main ]

Configure the checkout step

Next, start working on the job steps. In this process, you implement both the build tasks and the deploy tasks in your pipeline design diagram.

  1. Under jobs, rename the build key to build_push_image.

  2. You want this workflow to run on Ubuntu 20.04, so change the runs-on key from ubuntu-latest to ubuntu-20.04.

  3. Delete the last two commands in the steps key, which are just examples for the template.

    Your file, without the comments, should look like this example:

    name: Build and push the latest build to staging

on:
  push:
    branches: [ main ]

jobs:
  build_push_image:
    runs-on: ubuntu-20.04

    steps:
      - uses: actions/checkout@v2

You now have a step that uses the checkout action. This action clones the repository into the job environment. This step is equivalent to the first action, Clone repo, in the pipeline design diagram.

Add Docker steps

Next, add actions to build your Docker image. You can adjust usage for these actions. This example uses only a few of the parameters available. For more information, see the GitHub build-push-action documentation.

  1. In the Marketplace tab in the right panel, search for docker login, and select the first result published by docker.

    Screenshot showing the search results listing Docker Login.

    Note

    Docker actions prior to version 2 had the login flow built-in, but on versions 2 and above, these actions are separated, so you need two actions to set the workflow correctly.

  2. Under Installation, select the copy icon to copy the usage YAML.

    Screenshot showing the copy function and selecting the Docker Login task.

  3. Paste the copied YAML below the actions/checkout@v2 action.

    Important

    Be careful with indentation when you use YAML. The name key should be aligned with the preceding uses key.

  4. Add the following values to the registry, username, and password keys:

    • registry: ${{ secrets.ACR_NAME }}
    • username: ${{ secrets.ACR_LOGIN }}
    • password: ${{ secrets.ACR_PASSWORD }}

  5. Delete the other keys, because they aren't used in this exercise.

  6. In the right panel under Marketplace, search for build and push docker images, and select the first result published by docker.

    Screenshot that shows the search results that list Build and push Docker images.

  7. Under Installation, select the copy icon to copy the usage YAML.

  8. Paste the copied YAML below the last key from the previously copied docker-login action.

  9. Rename the name key from Build and push Docker images to Build and push staging images.

  10. Add the following values to the context, push, and tags keys:

    • context: .
    • push: true
    • tags: ${{secrets.ACR_NAME}}/contoso-website:latest

  11. Delete the other keys, because they aren't used in this exercise.

  12. Add another action called docker/setup-buildx-action between the checkout action and the login action, to set up the build engine for Docker to use. Copy the following snippet and paste it between the checkout and login actions.

    - name: Set up Buildx
  uses: docker/setup-buildx-action@v3.0.0

    Your final file, without the comments, should look like the following example:

    name: Build and push the latest build to staging

on:
  push:
    branches: [ main ]

jobs:
  build_push_image:
    runs-on: ubuntu-20.04

    steps:
      - uses: actions/checkout@v2

      - name: Set up Buildx
        uses: docker/setup-buildx-action@v3.0.0

      - name: Docker Login
        uses: docker/login-action@v3.0.0
        with:
          registry: ${{ secrets.ACR_NAME }}
          username: ${{ secrets.ACR_LOGIN }}
          password: ${{ secrets.ACR_PASSWORD }}

      - name: Build and push staging images
        uses: docker/build-push-action@v5.0.0
        with:
          context: .
          push: true
          tags: ${{secrets.ACR_NAME}}/contoso-website:latest

Commit the changes

To commit your changes, select the Commit changes button at upper right. On the Commit changes screen, enter a description for the commit, and then select Commit changes.

Screenshot that shows the Commit changes button in the Commit changes pane.

Selecting Commit changes triggers a new build, but this build fails because you haven't set the secrets yet.

Set the secrets

To set the secrets, on your GitHub repository page, select the Settings tab, and then select Secrets and variables > Actions from the left menu. Define the following secrets that your workflow uses:

  • ACR_NAME: The ACR_Name value returned by the setup script
  • ACR_LOGIN: The ACR Login Username value returned by the setup script
  • ACR_PASSWORD: The ACR Login Password value returned by the setup script
  • RESOURCE_GROUP: The Resource Group Name value returned by the setup script
  • CLUSTER_NAME: contoso-video

To define each secret:

  1. Select New repository secret.
  2. For Name, enter the secret name from the preceding list.
  3. For Secret, enter the value you saved from the setup script, or run a Cloud Shell query to get the value.
  4. Select Add secret.

Run optional queries to get the secrets values

If you don't have the values the setup script returned, you can run the following commands in Azure Cloud Shell to get the information:

  • ACR_NAME:

    az acr list --query "[?contains(resourceGroup, 'mslearn-gh-pipelines')].loginServer" -o table

  • ACR_LOGIN:

    az acr credential show --name <ACR_NAME> --query "username" -o table

  • ACR_PASSWORD:

    az acr credential show --name <ACR_NAME> --query "passwords[0].value" -o table

  • RESOURCE_GROUP:

    az aks list -o tsv --query "[?name=='contoso-video'].resourceGroup"

Run the job

  1. Select the Actions tab.

  2. Select the only execution in the list, the failed build-staging.yml job.

  3. At upper right, select Re-run jobs > Re-run all jobs, and on the Re-run all jobs screen, select Re-run jobs.

    Screenshot that shows the Re-run jobs and Re-run all jobs buttons.

  4. When the build completes, run az acr repository list --name <ACR_NAME> -o table in Cloud Shell to confirm that the contoso-website Container Registry repository appears in the results.

Continue to the next unit to build your production workflow.