name: Create and publish a Docker image

# Configures this workflow to run every time a change is pushed to the branch called `release`.
on:
    push:
        branches: ['release']

# Defines two custom environment variables for the workflow. These are used for the Container registry domain, and a name for the Docker image that this workflow builds.
env:
    REGISTRY: ghcr.io
    IMAGE_NAME: ${{ github.repository }}

# There is a single job in this workflow. It's configured to run on the latest available version of Ubuntu.
jobs:
    build-and-push-image:
        runs-on: ubuntu-latest
        # Sets the permissions granted to the `GITHUB_TOKEN` for the actions in this job.
        permissions:
            contents: read
            packages: write
            #
        steps:
            - name: Checkout repository
              uses: actions/checkout@v4
            # Uses the `docker/login-action` action to log in to the Container registry registry using the account and password that will publish the packages. Once published, the packages are scoped to the account defined here.
            - name: Log in to the Container registry
              uses: docker/login-action@65b78e6e13532edd9afa3aa52ac7964289d1a9c1
              with:
                  registry: ${{ env.REGISTRY }}
                  username: ${{ github.actor }}
                  password: ${{ secrets.GITHUB_TOKEN }}
            # This step uses [docker/metadata-action](https://github.com/docker/metadata-action#about) to extract tags and labels that will be applied to the specified image. The `id` "meta" allows the output of this step to be referenced in a subsequent step. The `images` value provides the base name for the tags and labels.
            - name: Extract metadata (tags, labels) for Docker
              id: meta
              uses: docker/metadata-action@9ec57ed1fcdbf14dcef7dfbe97b2010124a938b7
              with:
                  images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
            # This step uses the `docker/build-push-action` action to build the image, based on your repository's `Dockerfile`. If the build succeeds, it pushes the image to GitHub Packages.
            # It uses the `context` parameter to define the build's context as the set of files located in the specified path. For more information, see "[Usage](https://github.com/docker/build-push-action#usage)" in the README of the `docker/build-push-action` repository.
            # It uses the `tags` and `labels` parameters to tag and label the image with the output from the "meta" step.
            - name: Build and push Docker image
              uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
              with:
                  context: .
                  push: true
                  tags: ${{ steps.meta.outputs.tags }}
                  labels: ${{ steps.meta.outputs.labels }}
