name: Docker Build
description: Build a Docker image with tags

inputs:
  image:
    description: Full image name (registry/org/name)
    required: true
  tags:
    description: Comma-separated list of tags
    default: 'latest'
  context:
    description: Build context path
    default: '.'
  dockerfile:
    description: Path to Dockerfile
    default: 'Dockerfile'
  build-args:
    description: Build arguments (KEY=value, newline-separated)
    default: ''

outputs:
  images:
    description: Built image references
    value: ${{ steps.build.outputs.images }}

runs:
  using: composite
  steps:
    - id: build
      shell: bash
      run: |
        IMAGE="${{ inputs.image }}"
        TAGS="${{ inputs.tags }}"
        CONTEXT="${{ inputs.context }}"
        DOCKERFILE="${{ inputs.dockerfile }}"
        BUILD_ARGS="${{ inputs.build-args }}"

        # Build tag arguments
        TAG_ARGS=""
        IMAGES=""
        IFS=',' read -ra TAG_ARRAY <<< "$TAGS"
        for tag in "${TAG_ARRAY[@]}"; do
          tag=$(echo "$tag" | xargs)  # trim whitespace
          TAG_ARGS="$TAG_ARGS -t $IMAGE:$tag"
          IMAGES="$IMAGES$IMAGE:$tag,"
        done
        IMAGES="${IMAGES%,}"  # remove trailing comma

        # Build build-arg arguments
        BUILD_ARG_ARGS=""
        if [ -n "$BUILD_ARGS" ]; then
          while IFS= read -r arg; do
            if [ -n "$arg" ]; then
              BUILD_ARG_ARGS="$BUILD_ARG_ARGS --build-arg $arg"
            fi
          done <<< "$BUILD_ARGS"
        fi

        # Build the image; retry on failure. Base-image pulls from external
        # registries flake on transient runner DNS/network issues, and the
        # BuildKit layer cache makes a retry of a failed build cheap.
        for attempt in 1 2; do
          if docker build $TAG_ARGS $BUILD_ARG_ARGS -f "$DOCKERFILE" "$CONTEXT"; then
            break
          fi
          if [ "$attempt" -eq 2 ]; then
            exit 1
          fi
          echo "build failed, retrying in 30s..."
          sleep 30
        done

        echo "images=$IMAGES" >> $GITHUB_OUTPUT