workflows: add shared docker-bake workflow

Add a shared callable workflow that performs a docker-build via `buildx
bake` and optionally pushes to ghcr.io.

Signed-off-by: David Rheinsberg <[email protected]>

.github/workflows/lib-docker-bake.yml

@@ -0,0 +1,151 @@
+#
+# lib-docker-bake - Build and deploy container images
+#
+# This is a callable workflow that uses `docker buildx bake` to build a
+# selected set of container images and then optionally deploys them.
+#
+
+name: "lib: build/deploy container images"
+
+on:
+  workflow_call:
+    inputs:
+      deploy:
+        default: false
+        description: "Deploy built images to their repositories"
+        required: false
+        type: boolean
+      ghcruser:
+        default: ""
+        description: "Username to use for authentication to ghcr.io (empty to skip)"
+        required: false
+        type: string
+      source:
+        default: "."
+        description: "Path to the source directory relative to the workspace"
+        required: false
+        type: string
+      target:
+        default: "default"
+        description: "Buildx target to work on"
+        required: true
+        type: string
+    secrets:
+      ghcrpass:
+        description: "Password to use for authentication to ghcr.io"
+        required: false
+
+defaults:
+  run:
+    shell: "bash"
+
+jobs:
+
+  #
+  # Configure Jobs
+  #
+  # This job prepares parameters for further processing. Amongst other things,
+  # it lists all targets and provides this output as JSON array to other
+  # jobs. This allows us to dynamically react to additions to the image list
+  # and create new jobs for each image.
+  #
+  # Note that we have to split image builds across jobs since the individual
+  # CI runners do not have enough disk capacity to build all images.
+  #
+  config:
+    name: "Job Configuration"
+
+    runs-on: ubuntu-latest
+
+    outputs:
+      images: ${{ steps.parameters.outputs.images }}
+      now: ${{ steps.parameters.outputs.now }}
+
+    steps:
+    - name: "Clone Repository"
+      uses: actions/checkout@v3
+
+    - name: "Determine Build Parameters"
+
+      id: parameters
+      working-directory: ${{ inputs.source }}
+
+      env:
+        CTX_INPUTS_TARGET: ${{ inputs.target }}
+
+      run: |
+        IMG_IMAGES=$(docker buildx bake --print "${CTX_INPUTS_TARGET}" | jq -ce ".target | keys")
+        IMG_NOW=$(date -u '+%Y%m%d%H%M')
+
+        echo "images=${IMG_IMAGES}" >>$GITHUB_OUTPUT
+        echo "now=${IMG_NOW}" >>$GITHUB_OUTPUT
+
+    - name: "Print Parameters"
+      env:
+        CTX_STEPS_PARAMETERS_OUTPUTS_IMAGES: ${{ steps.parameters.outputs.images }}
+        CTX_STEPS_PARAMETERS_OUTPUTS_NOW: ${{ steps.parameters.outputs.now }}
+      run: |
+        echo "Images:"
+        echo "${CTX_STEPS_PARAMETERS_OUTPUTS_IMAGES}" | jq .
+        echo "End of Images"
+        echo "Now: ${CTX_STEPS_PARAMETERS_OUTPUTS_NOW}"
+
+  #
+  # Build/Test Container Image
+  #
+  # This job is run for each target. It builds the container image locally and
+  # then runs configured tests (if any).
+  #
+  ci:
+    name: "Container Build/Test"
+
+    needs: config
+    runs-on: ubuntu-latest
+
+    env:
+      RAE_UNIQUEID: ${{ needs.config.outputs.now }}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        image: ${{ fromJson(needs.config.outputs.images) }}
+
+    steps:
+    - name: "Clone Repository"
+      uses: actions/checkout@v3
+
+    - name: "Prepare QEMU Emulators"
+      uses: docker/setup-qemu-action@v2
+
+    - name: "Prepare Docker Buildx"
+      id: buildx
+      uses: docker/setup-buildx-action@v2
+
+    - name: "Build Image"
+
+      env:
+        CTX_MATRIX_IMAGE: ${{ matrix.image }}
+
+      working-directory: ${{ inputs.source }}
+      run: docker buildx bake --load "${CTX_MATRIX_IMAGE}"
+
+    - name: "Authenticate to GHCR"
+      if: inputs.deploy && inputs.ghcruser != ''
+
+      uses: docker/login-action@v2
+      with:
+        registry: ghcr.io
+        username: ${{ inputs.ghcruser }}
+        password: ${{ secrets.ghcrpass }}
+
+    - name: "Deploy Image"
+      if: inputs.deploy && inputs.ghcruser != ''
+
+      env:
+        CTX_MATRIX_IMAGE: ${{ matrix.image }}
+
+      working-directory: ${{ inputs.source }}
+      run: |
+        docker buildx bake --print "${CTX_MATRIX_IMAGE}" | \
+            jq -cer '.target[].tags[] | select(test("^ghcr.io"))' | \
+            xargs -L1 -- docker push