使用 GitHub Actions 建立多平台映像檔

您可以使用 platforms 選項來建置多平台映像檔，如下列範例所示：

注意
關於可用平台列表，請參閱 Docker Setup Buildx 動作 (Action)。
若您需要支援更多平台，可以使用 QEMU 搭配 Docker Setup QEMU 動作。

name: ci

on:
  push:

jobs:
  docker:
    runs-on: ubuntu-latest
    steps:
      - name: Login to Docker Hub
        uses: docker/login-action@v3
        with:
          username: ${{ vars.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          platforms: linux/amd64,linux/arm64
          push: true
          tags: user/app:latest

建置並載入多平台映像檔

GitHub Actions 執行器的預設 Docker 設定不支援在建置完成後將多平台映像檔載入至執行器的本機映像檔儲存庫。若要載入多平台映像檔，您需要為 Docker Engine 啟用 containerd 映像檔儲存庫選項。

目前無法直接在 GitHub Actions 執行器中設定預設的 Docker 設定，但您可以使用 docker/setup-docker-action 來為工作 (Job) 自訂 Docker Engine 與 CLI 設定。

下列的工作流程範例啟用 containerd 映像檔儲存庫、建置多平台映像檔，並將結果載入至 GitHub 執行器的本機映像檔儲存庫。

name: ci

on:
  push:

jobs:
  docker:
    runs-on: ubuntu-latest
    steps:
      - name: Set up Docker
        uses: docker/setup-docker-action@v4
        with:
          daemon-config: |
            {
              "debug": true,
              "features": {
                "containerd-snapshotter": true
              }
            }

      - name: Login to Docker Hub
        uses: docker/login-action@v3
        with:
          username: ${{ vars.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          platforms: linux/amd64,linux/arm64
          load: true
          tags: user/app:latest

跨多個執行器 (Runners) 分散建置工作

在上述範例中，每個平台都在同一個執行器上進行建置，根據平台數量和您的 Dockerfile 大小，這可能需要很長的時間。

為了解決此問題，您可以使用矩陣 (Matrix) 策略，將每個平台的建置工作分配到多個執行器上，並使用 buildx imagetools create 指令來建立清單清單 (Manifest list)。

下列工作流程將使用矩陣策略在專屬執行器上為每個平台建置映像檔，並透過摘要 (Digest) 推送。接著，merge 工作將建立清單清單並將其推送到 Docker Hub。metadata 動作用於設定標籤 (Tags) 與標記 (Labels)。

name: ci

on:
  push:

env:
  REGISTRY_IMAGE: user/app

jobs:
  build:
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      matrix:
        platform:
          - linux/amd64
          - linux/arm64
    steps:
      - name: Prepare
        run: |
          platform=${{ matrix.platform }}
          echo "PLATFORM_PAIR=${platform//\//-}" >> $GITHUB_ENV

      - name: Docker meta
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY_IMAGE }}

      - name: Login to Docker Hub
        uses: docker/login-action@v3
        with:
          username: ${{ vars.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Build and push by digest
        id: build
        uses: docker/build-push-action@v6
        with:
          platforms: ${{ matrix.platform }}
          labels: ${{ steps.meta.outputs.labels }}
          tags: ${{ env.REGISTRY_IMAGE }}
          outputs: type=image,push-by-digest=true,name-canonical=true,push=true

      - name: Export digest
        run: |
          mkdir -p ${{ runner.temp }}/digests
          digest="${{ steps.build.outputs.digest }}"
          touch "${{ runner.temp }}/digests/${digest#sha256:}"

      - name: Upload digest
        uses: actions/upload-artifact@v4
        with:
          name: digests-${{ env.PLATFORM_PAIR }}
          path: ${{ runner.temp }}/digests/*
          if-no-files-found: error
          retention-days: 1

  merge:
    runs-on: ubuntu-latest
    needs:
      - build
    steps:
      - name: Download digests
        uses: actions/download-artifact@v4
        with:
          path: ${{ runner.temp }}/digests
          pattern: digests-*
          merge-multiple: true

      - name: Login to Docker Hub
        uses: docker/login-action@v3
        with:
          username: ${{ vars.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Docker meta
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY_IMAGE }}
          tags: |
            type=ref,event=branch
            type=ref,event=pr
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}

      - name: Create manifest list and push
        working-directory: ${{ runner.temp }}/digests
        run: |
          docker buildx imagetools create $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
            $(printf '${{ env.REGISTRY_IMAGE }}@sha256:%s ' *)

      - name: Inspect image
        run: |
          docker buildx imagetools inspect ${{ env.REGISTRY_IMAGE }}:${{ steps.meta.outputs.version }}

使用 Bake

也可以使用 Bake 搭配 bake 動作在多個執行器上進行建置。

您可以在此 GitHub 儲存庫中找到實際範例。

以下範例達到的結果與上一節所述相同。

variable "DEFAULT_TAG" {
  default = "app:local"
}

// Special target: https://github.com/docker/metadata-action#bake-definition
target "docker-metadata-action" {
  tags = ["${DEFAULT_TAG}"]
}

// Default target if none specified
group "default" {
  targets = ["image-local"]
}

target "image" {
  inherits = ["docker-metadata-action"]
}

target "image-local" {
  inherits = ["image"]
  output = ["type=docker"]
}

target "image-all" {
  inherits = ["image"]
  platforms = [
    "linux/amd64",
    "linux/arm/v6",
    "linux/arm/v7",
    "linux/arm64"
  ]
}

name: ci

on:
  push:

env:
  REGISTRY_IMAGE: user/app

jobs:
  prepare:
    runs-on: ubuntu-latest
    outputs:
      matrix: ${{ steps.platforms.outputs.matrix }}
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Create matrix
        id: platforms
        run: |
          echo "matrix=$(docker buildx bake image-all --print | jq -cr '.target."image-all".platforms')" >>${GITHUB_OUTPUT}

      - name: Show matrix
        run: |
          echo ${{ steps.platforms.outputs.matrix }}

      - name: Docker meta
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY_IMAGE }}

      - name: Rename meta bake definition file
        run: |
          mv "${{ steps.meta.outputs.bake-file }}" "${{ runner.temp }}/bake-meta.json"

      - name: Upload meta bake definition
        uses: actions/upload-artifact@v4
        with:
          name: bake-meta
          path: ${{ runner.temp }}/bake-meta.json
          if-no-files-found: error
          retention-days: 1

  build:
    runs-on: ubuntu-latest
    needs:
      - prepare
    strategy:
      fail-fast: false
      matrix:
        platform: ${{ fromJson(needs.prepare.outputs.matrix) }}
    steps:
      - name: Prepare
        run: |
          platform=${{ matrix.platform }}
          echo "PLATFORM_PAIR=${platform//\//-}" >> $GITHUB_ENV

      - name: Download meta bake definition
        uses: actions/download-artifact@v4
        with:
          name: bake-meta
          path: ${{ runner.temp }}
      
      - name: Login to Docker Hub
        uses: docker/login-action@v3
        with:
          username: ${{ vars.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Build
        id: bake
        uses: docker/bake-action@v6
        with:
          files: |
            ./docker-bake.hcl
            cwd://${{ runner.temp }}/bake-meta.json
          targets: image
          set: |
            *.tags=${{ env.REGISTRY_IMAGE }}
            *.platform=${{ matrix.platform }}
            *.output=type=image,push-by-digest=true,name-canonical=true,push=true

      - name: Export digest
        run: |
          mkdir -p ${{ runner.temp }}/digests
          digest="${{ fromJSON(steps.bake.outputs.metadata).image['containerimage.digest'] }}"
          touch "${{ runner.temp }}/digests/${digest#sha256:}"

      - name: Upload digest
        uses: actions/upload-artifact@v4
        with:
          name: digests-${{ env.PLATFORM_PAIR }}
          path: ${{ runner.temp }}/digests/*
          if-no-files-found: error
          retention-days: 1

  merge:
    runs-on: ubuntu-latest
    needs:
      - build
    steps:
      - name: Download meta bake definition
        uses: actions/download-artifact@v4
        with:
          name: bake-meta
          path: ${{ runner.temp }}

      - name: Download digests
        uses: actions/download-artifact@v4
        with:
          path: ${{ runner.temp }}/digests
          pattern: digests-*
          merge-multiple: true

      - name: Login to DockerHub
        uses: docker/login-action@v3
        with:
          username: ${{ vars.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Create manifest list and push
        working-directory: ${{ runner.temp }}/digests
        run: |
          docker buildx imagetools create $(jq -cr '.target."docker-metadata-action".tags | map(select(startswith("${{ env.REGISTRY_IMAGE }}")) | "-t " + .) | join(" ")' ${{ runner.temp }}/bake-meta.json) \
            $(printf '${{ env.REGISTRY_IMAGE }}@sha256:%s ' *)

      - name: Inspect image
        run: |
          docker buildx imagetools inspect ${{ env.REGISTRY_IMAGE }}:$(jq -r '.target."docker-metadata-action".args.DOCKER_META_VERSION' ${{ runner.temp }}/bake-meta.json)