actions/docker-build/action.yml

# yaml-language-server: $schema=https://json.schemastore.org/github-action.json
# permissions:
#   - (none required)  # Build action, publishing handled by separate actions
---
name: Docker Build
description: 'Builds a Docker image for multiple architectures with enhanced security and reliability.'
author: 'Ismo Vuorinen'

branding:
  icon: 'package'
  color: 'blue'

inputs:
  image-name:
    description: 'The name of the Docker image to build. Defaults to the repository name.'
    required: false
  tag:
    description: 'The tag for the Docker image. Must follow semver or valid Docker tag format.'
    required: true
  architectures:
    description: 'Comma-separated list of architectures to build for.'
    required: false
    default: 'linux/amd64,linux/arm64,linux/arm/v7,linux/arm/v6'
  dockerfile:
    description: 'Path to the Dockerfile'
    required: false
    default: 'Dockerfile'
  context:
    description: 'Docker build context'
    required: false
    default: '.'
  build-args:
    description: 'Build arguments in format KEY=VALUE,KEY2=VALUE2'
    required: false
  cache-from:
    description: 'External cache sources (e.g., type=registry,ref=user/app:cache)'
    required: false
  push:
    description: 'Whether to push the image after building'
    required: false
    default: 'true'
  max-retries:
    description: 'Maximum number of retry attempts for build and push operations'
    required: false
    default: '3'
  token:
    description: 'GitHub token for authentication'
    required: false
    default: ''
  buildx-version:
    description: 'Specific Docker Buildx version to use'
    required: false
    default: 'latest'
  buildkit-version:
    description: 'Specific BuildKit version to use'
    required: false
    default: 'v0.11.0'
  cache-mode:
    description: 'Cache mode for build layers (min, max, or inline)'
    required: false
    default: 'max'
  build-contexts:
    description: 'Additional build contexts in format name=path,name2=path2'
    required: false
  network:
    description: 'Network mode for build (host, none, or default)'
    required: false
    default: 'default'
  secrets:
    description: 'Build secrets in format id=path,id2=path2'
    required: false
  auto-detect-platforms:
    description: 'Automatically detect and build for all available platforms'
    required: false
    default: 'false'
  platform-build-args:
    description: 'Platform-specific build args in JSON format'
    required: false
  parallel-builds:
    description: 'Number of parallel platform builds (0 for auto)'
    required: false
    default: '0'
  cache-export:
    description: 'Export cache destination (e.g., type=local,dest=/tmp/cache)'
    required: false
  cache-import:
    description: 'Import cache sources (e.g., type=local,src=/tmp/cache)'
    required: false
  dry-run:
    description: 'Perform a dry run without actually building'
    required: false
    default: 'false'
  verbose:
    description: 'Enable verbose logging with platform-specific output'
    required: false
    default: 'false'
  platform-fallback:
    description: 'Continue building other platforms if one fails'
    required: false
    default: 'true'
  scan-image:
    description: 'Scan built image for vulnerabilities'
    required: false
    default: 'false'
  sign-image:
    description: 'Sign the built image with cosign'
    required: false
    default: 'false'
  sbom-format:
    description: 'SBOM format (spdx-json, cyclonedx-json, or syft-json)'
    required: false
    default: 'spdx-json'

outputs:
  image-digest:
    description: 'The digest of the built image'
    value: ${{ steps.build.outputs.digest }}
  metadata:
    description: 'Build metadata in JSON format'
    value: ${{ steps.build.outputs.metadata }}
  platforms:
    description: 'Successfully built platforms'
    value: ${{ steps.platforms.outputs.built }}
  platform-matrix:
    description: 'Build status per platform in JSON format'
    value: ${{ steps.build.outputs.platform-matrix }}
  build-time:
    description: 'Total build time in seconds'
    value: ${{ steps.build.outputs.build-time }}
  scan-results:
    description: 'Vulnerability scan results if scanning enabled'
    value: ${{ steps.scan-output.outputs.results }}
  signature:
    description: 'Image signature if signing enabled'
    value: ${{ steps.sign.outputs.signature }}
  sbom-location:
    description: 'SBOM document location'
    value: ${{ steps.build.outputs.sbom-location }}

runs:
  using: composite
  steps:
    - name: Validate Inputs
      id: validate
      uses: ./validate-inputs
      with:
        action-type: 'docker-build'
        image-name: ${{ inputs.image-name }}
        tag: ${{ inputs.tag }}
        architectures: ${{ inputs.architectures }}
        dockerfile: ${{ inputs.dockerfile }}
        build-args: ${{ inputs.build-args }}
        buildx-version: ${{ inputs.buildx-version }}
        parallel-builds: ${{ inputs.parallel-builds }}

    - name: Check Dockerfile Exists
      shell: bash
      env:
        DOCKERFILE: ${{ inputs.dockerfile }}
      run: |
        if [ ! -f "$DOCKERFILE" ]; then
          echo "::error::Dockerfile not found at $DOCKERFILE"
          exit 1
        fi

    - name: Set up QEMU
      uses: docker/setup-qemu-action@29109295f81e9208d7d86ff1c6c12d2833863392 # v3.6.0
      with:
        platforms: ${{ inputs.architectures }}

    - name: Set up Docker Buildx
      id: buildx
      uses: docker/setup-buildx-action@e468171a9de216ec08956ac3ada2f0791b6bd435 # v3.11.1
      with:
        version: ${{ inputs.buildx-version }}
        platforms: ${{ inputs.architectures }}
        buildkitd-flags: --debug
        driver-opts: |
          network=${{ inputs.network }}
          image=moby/buildkit:${{ inputs.buildkit-version }}

    - name: Detect Available Platforms
      id: detect-platforms
      if: inputs.auto-detect-platforms == 'true'
      shell: bash
      env:
        ARCHITECTURES: ${{ inputs.architectures }}
      run: |
        set -euo pipefail

        # Get available platforms from buildx
        available_platforms=$(docker buildx ls | grep -o 'linux/[^ ]*' | sort -u | tr '\n' ',' | sed 's/,$//')

        if [ -n "$available_platforms" ]; then
          echo "platforms=${available_platforms}" >> $GITHUB_OUTPUT
          echo "Detected platforms: ${available_platforms}"
        else
          echo "platforms=$ARCHITECTURES" >> $GITHUB_OUTPUT
          echo "Using default platforms: $ARCHITECTURES"
        fi

    - name: Determine Image Name
      id: image-name
      shell: bash
      env:
        IMAGE_NAME: ${{ inputs.image-name }}
      run: |
        set -euo pipefail

        if [ -z "$IMAGE_NAME" ]; then
          repo_name=$(basename "${GITHUB_REPOSITORY}")
          echo "name=${repo_name}" >> $GITHUB_OUTPUT
        else
          echo "name=$IMAGE_NAME" >> $GITHUB_OUTPUT
        fi

    - name: Parse Build Arguments
      id: build-args
      shell: bash
      env:
        BUILD_ARGS_INPUT: ${{ inputs.build-args }}
      run: |
        set -euo pipefail

        args=""
        if [ -n "$BUILD_ARGS_INPUT" ]; then
          IFS=',' read -ra BUILD_ARGS <<< "$BUILD_ARGS_INPUT"
          for arg in "${BUILD_ARGS[@]}"; do
            args="$args --build-arg $arg"
          done
        fi
        echo "args=${args}" >> $GITHUB_OUTPUT

    - name: Parse Build Contexts
      id: build-contexts
      shell: bash
      env:
        BUILD_CONTEXTS: ${{ inputs.build-contexts }}
      run: |
        set -euo pipefail

        contexts=""
        if [ -n "$BUILD_CONTEXTS" ]; then
          IFS=',' read -ra CONTEXTS <<< "$BUILD_CONTEXTS"
          for ctx in "${CONTEXTS[@]}"; do
            contexts="$contexts --build-context $ctx"
          done
        fi
        echo "contexts=${contexts}" >> $GITHUB_OUTPUT

    - name: Parse Secrets
      id: secrets
      shell: bash
      env:
        INPUT_SECRETS: ${{ inputs.secrets }}
      run: |
        set -euo pipefail

        secrets=""
        if [ -n "$INPUT_SECRETS" ]; then
          IFS=',' read -ra SECRETS <<< "$INPUT_SECRETS"
          for secret in "${SECRETS[@]}"; do
            # Trim whitespace
            secret=$(echo "$secret" | xargs)

            if [[ "$secret" == *"="* ]]; then
              # Parse id=src format
              id="${secret%%=*}"
              src="${secret#*=}"

              # Validate id and src are not empty
              if [[ -z "$id" || -z "$src" ]]; then
                echo "::error::Invalid secret format: '$secret'. Expected 'id=src' where both id and src are non-empty"
                exit 1
              fi

              secrets="$secrets --secret id=$id,src=$src"
            else
              # Handle legacy format - treat as id only (error for now)
              echo "::error::Invalid secret format: '$secret'. Expected 'id=src' format for Buildx compatibility"
              exit 1
            fi
          done
        fi
        echo "secrets=${secrets}" >> $GITHUB_OUTPUT

    - name: Login to GitHub Container Registry
      if: ${{ inputs.push == 'true' }}
      uses: docker/login-action@5e57cd118135c172c3672efd75eb46360885c0ef # v3.6.0
      with:
        registry: ghcr.io
        username: ${{ github.actor }}
        password: ${{ inputs.token || github.token }}

    - name: Set up Build Cache
      id: cache
      shell: bash
      env:
        CACHE_IMPORT: ${{ inputs.cache-import }}
        CACHE_FROM: ${{ inputs.cache-from }}
        CACHE_EXPORT: ${{ inputs.cache-export }}
        PUSH: ${{ inputs.push }}
        INPUT_TOKEN: ${{ inputs.token }}
        CACHE_MODE: ${{ inputs.cache-mode }}
      run: |
        set -euo pipefail

        # Use provided token or fall back to GITHUB_TOKEN
        TOKEN="${INPUT_TOKEN:-${GITHUB_TOKEN:-}}"

        cache_from=""
        cache_to=""

        # Handle cache import
        if [ -n "$CACHE_IMPORT" ]; then
          cache_from="--cache-from $CACHE_IMPORT"
        elif [ -n "$CACHE_FROM" ]; then
          cache_from="--cache-from $CACHE_FROM"
        fi

        # Handle cache export
        if [ -n "$CACHE_EXPORT" ]; then
          cache_to="--cache-to $CACHE_EXPORT"
        fi

        # Registry cache configuration for better performance (only if authenticated)
        if [ "$PUSH" == "true" ] || [ -n "$TOKEN" ]; then
          normalized_repo=$(echo "${GITHUB_REPOSITORY}" | tr '[:upper:]' '[:lower:]' | sed 's/[^a-z0-9._\/-]/-/g')
          registry_cache_ref="ghcr.io/${normalized_repo}/cache:latest"
          cache_from="$cache_from --cache-from type=registry,ref=$registry_cache_ref"

          # Set cache mode
          cache_mode="$CACHE_MODE"
          if [ -z "$cache_to" ]; then
            cache_to="--cache-to type=registry,ref=$registry_cache_ref,mode=${cache_mode}"
          fi
        fi

        # Also include local cache as fallback
        cache_from="$cache_from --cache-from type=local,src=/tmp/.buildx-cache"
        if [[ "$cache_to" != *"type=local"* ]]; then
          cache_to="$cache_to --cache-to type=local,dest=/tmp/.buildx-cache-new,mode=${cache_mode}"
        fi

        echo "from=${cache_from}" >> $GITHUB_OUTPUT
        echo "to=${cache_to}" >> $GITHUB_OUTPUT

    - name: Build Multi-Architecture Docker Image
      id: build
      shell: bash
      env:
        AUTO_DETECT_PLATFORMS: ${{ inputs.auto-detect-platforms }}
        DETECTED_PLATFORMS: ${{ steps.detect-platforms.outputs.platforms }}
        ARCHITECTURES: ${{ inputs.architectures }}
        PUSH: ${{ inputs.push }}
        DRY_RUN: ${{ inputs.dry-run }}
        MAX_RETRIES: ${{ inputs.max-retries }}
        VERBOSE: ${{ inputs.verbose }}
        SBOM_FORMAT: ${{ inputs.sbom-format }}
        IMAGE_NAME: ${{ steps.image-name.outputs.name }}
        TAG: ${{ inputs.tag }}
        BUILD_ARGS: ${{ steps.build-args.outputs.args }}
        BUILD_CONTEXTS: ${{ steps.build-contexts.outputs.contexts }}
        SECRETS: ${{ steps.secrets.outputs.secrets }}
        CACHE_FROM: ${{ steps.cache.outputs.from }}
        CACHE_TO: ${{ steps.cache.outputs.to }}
        DOCKERFILE: ${{ inputs.dockerfile }}
        CONTEXT: ${{ inputs.context }}
      run: |
        set -euo pipefail

        # Track build start time
        build_start=$(date +%s)

        # Determine platforms to build
        if [ "$AUTO_DETECT_PLATFORMS" == "true" ] && [ -n "$DETECTED_PLATFORMS" ]; then
          platforms="$DETECTED_PLATFORMS"
        else
          platforms="$ARCHITECTURES"
        fi

        # For local load (push=false), restrict to single platform
        if [ "$PUSH" != "true" ]; then
          # Extract first platform only for local load
          platforms=$(echo "$platforms" | cut -d',' -f1)
          echo "Local build mode: restricting to single platform: $platforms"
        fi

        # Initialize platform matrix tracking
        platform_matrix="{}"

        # Check for dry run
        if [ "$DRY_RUN" == "true" ]; then
          echo "[DRY RUN] Would build for platforms: $platforms"
          echo "digest=dry-run-no-digest" >> $GITHUB_OUTPUT
          echo "platform-matrix={}" >> $GITHUB_OUTPUT
          echo "build-time=0" >> $GITHUB_OUTPUT
          exit 0
        fi

        attempt=1
        max_attempts="$MAX_RETRIES"

        # Prepare verbose flag
        verbose_flag=""
        if [ "$VERBOSE" == "true" ]; then
          verbose_flag="--progress=plain"
        fi

        # Prepare SBOM options
        sbom_flag="--sbom=true"
        if [ -n "$SBOM_FORMAT" ]; then
          sbom_flag="--sbom=true --sbom-format=$SBOM_FORMAT"
        fi

        while [ $attempt -le $max_attempts ]; do
          echo "Build attempt $attempt of $max_attempts"

          # Build command with platform restriction for local load
          if [ "$PUSH" == "true" ]; then
            build_action="--push"
          else
            build_action="--load"
          fi

          if docker buildx build \
            --platform=${platforms} \
            --tag "$IMAGE_NAME:$TAG" \
            $BUILD_ARGS \
            $BUILD_CONTEXTS \
            $SECRETS \
            $CACHE_FROM \
            $CACHE_TO \
            --file "$DOCKERFILE" \
            ${build_action} \
            --provenance=true \
            ${sbom_flag} \
            ${verbose_flag} \
            --metadata-file=/tmp/build-metadata.json \
            "$CONTEXT"; then

            # Get image digest
            if [ "$PUSH" == "true" ]; then
              digest=$(docker buildx imagetools inspect "$IMAGE_NAME:$TAG" --raw | jq -r '.digest // "unknown"' || echo "unknown")
            else
              digest=$(docker inspect "$IMAGE_NAME:$TAG" --format='{{.Id}}' || echo "unknown")
            fi
            echo "digest=${digest}" >> $GITHUB_OUTPUT

            # Parse metadata
            if [ -f /tmp/build-metadata.json ]; then
              {
                echo "metadata<<EOF"
                cat /tmp/build-metadata.json
                echo "EOF"
              } >> "$GITHUB_OUTPUT"

              # Extract SBOM location directly from file
              sbom_location=$(jq -r '.sbom.location // ""' /tmp/build-metadata.json)
              echo "sbom-location=${sbom_location}" >> "$GITHUB_OUTPUT"
            fi

            # Calculate build time
            build_end=$(date +%s)
            build_time=$((build_end - build_start))
            echo "build-time=${build_time}" >> $GITHUB_OUTPUT

            # Build platform matrix
            IFS=',' read -ra PLATFORM_ARRAY <<< "${platforms}"
            platform_matrix="{"
            for p in "${PLATFORM_ARRAY[@]}"; do
              platform_matrix="${platform_matrix}\"${p}\":\"success\","
            done
            platform_matrix="${platform_matrix%,}}"
            echo "platform-matrix=${platform_matrix}" >> $GITHUB_OUTPUT

            # Move cache
            if [ -d /tmp/.buildx-cache-new ]; then
              rm -rf /tmp/.buildx-cache
              mv /tmp/.buildx-cache-new /tmp/.buildx-cache
            fi

            break
          fi

          attempt=$((attempt + 1))
          if [ $attempt -le $max_attempts ]; then
            echo "Build failed, waiting 10 seconds before retry..."
            sleep 10
          else
            echo "::error::Build failed after $max_attempts attempts"
            exit 1
          fi
        done

    - name: Scan Image for Vulnerabilities
      id: scan
      if: inputs.scan-image == 'true' && inputs.dry-run != 'true'
      uses: aquasecurity/trivy-action@b6643a29fecd7f34b3597bc6acb0a98b03d33ff8 # 0.33.1
      with:
        scan-type: 'image'
        image-ref: ${{ steps.image-name.outputs.name }}:${{ inputs.tag }}
        format: 'json'
        output: 'trivy-results.json'
        severity: 'HIGH,CRITICAL'

    - name: Process Scan Results
      id: scan-output
      if: inputs.scan-image == 'true' && inputs.dry-run != 'true'
      shell: bash
      run: |
        set -euo pipefail

        # Read and format scan results for output
        scan_results=$(cat trivy-results.json | jq -c '.')
        echo "results=${scan_results}" >> $GITHUB_OUTPUT

        # Check for critical vulnerabilities
        critical_count=$(cat trivy-results.json | jq '.Results[] | (.Vulnerabilities // [])[] | select(.Severity == "CRITICAL") | .VulnerabilityID' | wc -l)
        if [ "$critical_count" -gt 0 ]; then
          echo "::warning::Found $critical_count critical vulnerabilities in image"
        fi

    - name: Install Cosign
      if: inputs.sign-image == 'true' && inputs.push == 'true' && inputs.dry-run != 'true'
      uses: sigstore/cosign-installer@d7543c93d881b35a8faa02e8e3605f69b7a1ce62 # v3.10.0

    - name: Sign Image
      id: sign
      if: inputs.sign-image == 'true' && inputs.push == 'true' && inputs.dry-run != 'true'
      shell: bash
      env:
        IMAGE_NAME: ${{ steps.image-name.outputs.name }}
        IMAGE_TAG: ${{ inputs.tag }}
      run: |
        set -euo pipefail

        # Sign the image (using keyless signing with OIDC)
        export COSIGN_EXPERIMENTAL=1
        cosign sign --yes "${IMAGE_NAME}:${IMAGE_TAG}"

        echo "signature=signed" >> $GITHUB_OUTPUT

    - name: Verify Build
      id: verify
      if: inputs.dry-run != 'true'
      shell: bash
      env:
        PUSH: ${{ inputs.push }}
        IMAGE_NAME: ${{ steps.image-name.outputs.name }}
        IMAGE_TAG: ${{ inputs.tag }}
      run: |
        set -euo pipefail

        # Verify image exists
        if [ "$PUSH" == "true" ]; then
          if ! docker buildx imagetools inspect "${IMAGE_NAME}:${IMAGE_TAG}" >/dev/null 2>&1; then
            echo "::error::Built image not found"
            exit 1
          fi

          # Get and verify platform support
          platforms=$(docker buildx imagetools inspect "${IMAGE_NAME}:${IMAGE_TAG}" | grep "Platform:" | cut -d' ' -f2)
          echo "built=${platforms}" >> $GITHUB_OUTPUT
        else
          # For local builds, just verify it exists
          if ! docker image inspect "${IMAGE_NAME}:${IMAGE_TAG}" >/dev/null 2>&1; then
            echo "::error::Built image not found locally"
            exit 1
          fi
          echo "built=local" >> $GITHUB_OUTPUT
        fi

    - name: Cleanup
      if: always()
      shell: bash
      run: |-
        set -euo pipefail

        # Cleanup temporary files
        rm -rf /tmp/.buildx-cache*

        # Remove builder instance if created
        if docker buildx ls | grep -q builder; then
          docker buildx rm builder || true
        fi