# This workflow builds a multi-arch Docker image using GitHub Actions and separated Github Runners with native support for ARM64 and AMD64 architectures, without using QEMU emulation.
# It uses Docker Buildx to build and push the image to GitHub Container Registry (GHCR).
name: Build multi arch Docker Image with separate Github Runners

on:
  workflow_dispatch:
    inputs:
      dsh_version:
        description: "DSH git ref to build (tag or branch)"
        required: true
        default: dsh-v0.2.1-rc.2
        type: string
      pnpm_version:
        description: "pnpm version used to build DSH"
        required: true
        default: "11.28.5"
        type: string
  push:
    branches:
      - main
    paths:
      - 'Dockerfile'
      - '.github/workflows/multi-build.yaml'
env:
  # The name of the Docker image to be built and pushed to GHCR
  # The image name is derived from the GitHub repository name and the GitHub Container Registry (GHCR) URL.
  # The image name will be in the format: ghcr.io/<owner>/<repo>
  GHCR_IMAGE: ghcr.io/${{ github.repository }}
  # workflow_dispatch inputs win; pushes to main fall back to the pinned
  # defaults. Both values flow into the Docker build args and the image tags.
  DSH_VERSION: ${{ inputs.dsh_version || 'dsh-v0.2.1-rc.2' }}
  PNPM_VERSION: ${{ inputs.pnpm_version || '11.28.5' }}
permissions:
  # Global permissions for the workflow, which can be overridden at the job level
  contents: read

concurrency:
  # This concurrency group ensures that only one job in the group runs at a time.
  # If a new job is triggered, the previous one will be canceled.
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  # The build job builds the Docker image for each platform specified in the matrix.
  build:
    strategy:
      fail-fast: false
      matrix:
        platform:
          - linux/amd64
          - linux/arm64
      # The matrix includes two platforms: linux/amd64 and linux/arm64.
      # The build job will run for each platform in the matrix.

    permissions:
      # Permissions for the build job, which can be overridden at the step level
      # The permissions are set to allow the job to write to the GitHub Container Registry (GHCR) and read from the repository.
      attestations: write
      actions: read
      checks: write
      contents: write
      deployments: none
      id-token: write
      issues: read
      discussions: read
      packages: write
      pages: none
      pull-requests: read
      repository-projects: read
      security-events: read
      statuses: read

    runs-on: ${{ matrix.platform == 'linux/amd64' && 'ubuntu-latest' || matrix.platform == 'linux/arm64' && 'ubuntu-24.04-arm' }}
    # The job runs on different runners based on the platform.
    # For linux/amd64, it runs on the latest Ubuntu runner.
    # For linux/arm64, it runs on an Ubuntu 24.04 ARM runner.
    # The runner is selected based on the platform specified in the matrix.

    name: Build Docker image for ${{ matrix.platform }}

    steps:
      -
        name: Prepare environment for current platform 
        # This step sets up the environment for the current platform being built.
        # It replaces the '/' character in the platform name with '-' and sets it as an environment variable.
        # This is useful for naming artifacts and other resources that cannot contain '/'.
        # The environment variable PLATFORMS_PAIR will be used later in the workflow.
        id: prepare
        run: |
          platform=${{ matrix.platform }}
          echo "PLATFORM_PAIR=${platform//\//-}" >> $GITHUB_ENV

      - name: Checkout
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        # This step checks out the code from the repository.
        # It uses the actions/checkout action to clone the repository into the runner's workspace.

      - name: Docker meta default
        # This step generates metadata for the Docker image.
        # It uses the docker/metadata-action to create metadata based on the repository information.
        # The metadata includes information such as the image name, tags, and labels.
        # The metadata will be used later in the workflow to build and push the Docker image.
        id: meta
        uses: docker/metadata-action@dc802804100637a589fabce1cb79ff13a1411302 # v6.2.0
        with:
          images: ${{ env.GHCR_IMAGE }}


      - name: Set up Docker Context for Buildx
        # This step sets up a Docker context for Buildx.
        # It creates a new context named "builders" that will be used for building the Docker image.
        # The context allows Buildx to use the Docker daemon for building images.
        id: buildx-context
        run: |
          docker context create builders

      - name: Set up Docker Buildx
        # This step sets up Docker Buildx, which is a Docker CLI plugin for extended build capabilities with BuildKit.
        # It uses the docker/setup-buildx-action to configure Buildx with the specified context and platforms.
        # The platforms are specified in the matrix and will be used for building the Docker image.
        uses: docker/setup-buildx-action@f87e5991a6d7451dcb8d9637bfbc97413f497069 # v4.4.1
        with:
          endpoint: builders
          platforms: ${{ matrix.platform }}

      - name: Login to GitHub Container Registry
        # This step logs in to the GitHub Container Registry (GHCR) using the docker/login-action.
        # It uses the GitHub actor's username and the GITHUB_TOKEN secret for authentication.
        uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f # v4.6.0
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}


      - name: Build and push by digest
        # This step builds and pushes the Docker image using Buildx.
        # It uses the docker/build-push-action to build the image with the specified context and platforms.
        # The image is built with the labels and annotations generated in the previous steps.
        # The outputs are configured to push the image by digest, which allows for better caching and versioning.
        # The cache-from and cache-to options are used to enable caching for the build process.
        # The cache is stored in GitHub Actions cache and is scoped to the repository, branch, and platform.
        id: build
        uses: docker/build-push-action@c3c9e263c25d99ce0380d002d59b67737d91b0dc # v7.4.0
        env:
          DOCKER_BUILDKIT: 1
          DSH_PORT: 3080
        with:
          context: .
          platforms: ${{ matrix.platform }}
          labels: ${{ steps.meta.outputs.labels }}
          build-args: |
            DSH_VERSION=${{ env.DSH_VERSION }}
            PNPM_VERSION=${{ env.PNPM_VERSION }}
          annotations: ${{ steps.meta.outputs.annotations }}
          outputs: type=image,name=${{ env.GHCR_IMAGE }},push-by-digest=true,name-canonical=true,push=true,oci-mediatypes=true
          cache-from: type=gha,scope=${{ github.repository }}-${{ github.ref_name }}-${{ matrix.platform }}
          cache-to: type=gha,scope=${{ github.repository }}-${{ github.ref_name }}-${{ matrix.platform }}


      - name: Export digest
        # This step exports the digest of the built image to a file.
        # It creates a directory in /tmp/digests and saves the digest of the image to a file.
        # The digest is obtained from the output of the build step.
        # The digest is used to uniquely identify the built image and can be used for further processing or verification.
        run: |
          mkdir -p /tmp/digests
          digest="${{ steps.build.outputs.digest }}"
          touch "/tmp/digests/${digest#sha256:}"

      - name: Upload digest
        # This step uploads the digest file to the GitHub Actions artifact storage.
        # It uses the actions/upload-artifact action to upload the file created in the previous step.
        # The artifact is named digests-${{ env.PLATFORM_PAIR }}, where PLATFORM_PAIR is the platform name with '/' replaced by '-'.
        # The artifact is retained for 1 day, and if no files are found, it will throw an error.      
        uses: actions/upload-artifact@cf430e030ddbb5b0abf93d22962f4752f3646cd9 # v7.0.2
        with:
          name: digests-${{ env.PLATFORM_PAIR }}
          path: /tmp/digests/*
          if-no-files-found: error
          retention-days: 1


  merge:
    # This job merges the Docker manifests for the different platforms built in the previous job.
    name: Merge Docker manifests
    runs-on: ubuntu-latest
    permissions:
      attestations: write
      actions: read
      checks: read
      contents: read
      deployments: none
      id-token: write
      issues: read
      discussions: read
      packages: write
      pages: none
      pull-requests: read
      repository-projects: read
      security-events: read
      statuses: read

    needs:
      - build
      # This job depends on the build job to complete before it starts.
      # It ensures that the Docker images for all platforms are built before merging the manifests.
    steps:
      - name: Download digests
        # This step downloads the digest files uploaded in the build job.
        # It uses the actions/download-artifact action to download the artifacts with the pattern digests-*.
        # The downloaded files are merged into the /tmp/digests directory.
        uses: actions/download-artifact@9000827ccba6bdab643e8b6fd33ac0654aef8333 # v8.0.2
        with:
          path: /tmp/digests
          pattern: digests-*
          merge-multiple: true


      - name: Docker meta
        # This step generates metadata for the Docker image.
        # It uses the docker/metadata-action to create metadata based on the repository information.
        # The metadata includes information such as the image name, tags, and labels.
        id: meta
        uses: docker/metadata-action@dc802804100637a589fabce1cb79ff13a1411302 # v6.2.0
        with:
          images: ${{ env.GHCR_IMAGE }}
          annotations: |
            type=org.opencontainers.image.description,value=${{ github.event.repository.description || 'No description provided' }}
          tags: |
            type=raw,value=main,enable=${{ github.ref_name == 'main' }}
            type=raw,value=latest,enable=${{ github.ref_name == 'main' }}
            type=raw,value=${{ env.DSH_VERSION }},enable=${{ github.ref_name == 'main' || github.event_name == 'workflow_dispatch' }}

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@f87e5991a6d7451dcb8d9637bfbc97413f497069 # v4.4.1
        # This step sets up Docker Buildx, which is a Docker CLI plugin for extended build capabilities with BuildKit.
        with:
          driver-opts: |
            network=host

      - name: Login to GitHub Container Registry
        uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f # v4.6.0
        # This step logs in to the GitHub Container Registry (GHCR) using the docker/login-action.
        # It uses the GitHub actor's username and the GITHUB_TOKEN secret for authentication.
        # The login is necessary to push the merged manifest list to GHCR.
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Get execution timestamp with RFC3339 format
        # This step gets the current execution timestamp in RFC3339 format.
        # It uses the date command to get the current UTC time and formats it as a string.
        # The timestamp is used for annotating the Docker manifest list.
        id: timestamp
        run: |
          echo "timestamp=$(date -u +"%Y-%m-%dT%H:%M:%SZ")" >> $GITHUB_OUTPUT

      - name: Create manifest list and pushs
        # This step creates a manifest list for the Docker images built for different platforms.
        # It uses the docker buildx imagetools create command to create the manifest list.
        # The manifest list is annotated with metadata such as description, creation timestamp, and source URL.
        # The annotations are obtained from the metadata generated in the previous steps.
        # The manifest list is pushed to the GitHub Container Registry (GHCR) with the specified tags.
        working-directory: /tmp/digests
        id: manifest-annotate
        continue-on-error: true
        run: |
              docker buildx imagetools create \
                $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
                --annotation='index:org.opencontainers.image.description=${{ github.event.repository.description }}' \
                --annotation='index:org.opencontainers.image.created=${{ steps.timestamp.outputs.timestamp }}' \
                --annotation='index:org.opencontainers.image.url=${{ github.event.repository.url }}' \
                --annotation='index:org.opencontainers.image.source=${{ github.event.repository.url }}' \
                $(printf '${{ env.GHCR_IMAGE }}@sha256:%s ' *)

      - name: Create manifest list and push without annotations
        # This step creates a manifest list for the Docker images built for different platforms.
        # It uses the docker buildx imagetools create command to create the manifest list.
        # The manifest list is created without annotations if the previous step fails.
        # The manifest list is pushed to the GitHub Container Registry (GHCR) with the specified tags.
        if: steps.manifest-annotate.outcome == 'failure'
        working-directory: /tmp/digests
        run: |
              docker buildx imagetools create  $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
                $(printf '${{ env.GHCR_IMAGE }}@sha256:%s ' *)

      - name: Inspect image
        # This step inspects the created manifest list to verify its contents.
        # It uses the docker buildx imagetools inspect command to display information about the manifest list.
        # The inspection output will show the platforms and tags associated with the manifest list.
        id: inspect
        run: |
          docker buildx imagetools inspect '${{ env.GHCR_IMAGE }}:${{ steps.meta.outputs.version }}'