About

GitHub Action to build and push Docker images with Buildx.

💡 See also:

• login action
• setup-buildx action
• setup-qemu action

---

• Usage
  • Git context
  • Path context
  • Isolated builders
  • Multi-platform image
• Advanced usage
  • Local registry
  • Leverage GitHub cache
  • Complete workflow
  • Update DockerHub repo description
• Customizing
  • inputs
  • outputs
• Troubleshooting
• Keep up-to-date with GitHub Dependabot
• Limitation

Usage

This action uses our setup-buildx action that extends the docker build command named buildx with the full support of the features provided by Moby BuildKit builder toolkit. This includes multi-arch build, build-secrets, remote cache, etc. and different builder deployment/namespacing options.

Git context

The default behavior of this action is to use the Git context invoked by your workflow.

name: ci

on:
  push:
    branches: master

jobs:
  main:
    runs-on: ubuntu-latest
    steps:
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
      -
        name: Login to DockerHub
        uses: docker/login-action@v1 
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      -
        name: Build and push
        id: docker_build
        uses: docker/build-push-action@v2
        with:
          push: true
          tags: user/app:latest
      -
        name: Image digest
        run: echo ${{ steps.docker_build.outputs.digest }}

If you want to authenticate against a private repository, you have to use a secret named GIT_AUTH_TOKEN to be able to authenticate against it with buildx:

      -
        name: Build and push
        id: docker_build
        uses: docker/build-push-action@v2
        with:
          push: true
          tags: user/app:latest
          secrets: |
            GIT_AUTH_TOKEN=${{ secrets.MYTOKEN }}            

⚠️ Subdir for Git context is not yet supported. For the moment you can use the path context.

Path context

You can also use the PATH context alongside the actions/checkout action.

name: ci

on:
  push:
    branches: master

jobs:
  path-context:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v2
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
      -
        name: Login to DockerHub
        uses: docker/login-action@v1
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      -
        name: Build and push
        uses: docker/build-push-action@v2
        with:
          context: .
          file: ./Dockerfile
          platforms: linux/amd64,linux/arm64,linux/386
          push: true
          tags: user/app:latest

Isolated builders

name: ci

on:
  push:
    branches: master

jobs:
  multi-builders:
    runs-on: ubuntu-latest
    steps:
      -
        uses: docker/setup-buildx-action@v1
        id: builder1
      -
        uses: docker/setup-buildx-action@v1
        id: builder2
      -
        name: Builder 1 name
        run: echo ${{ steps.builder1.outputs.name }}
      -
        name: Builder 2 name
        run: echo ${{ steps.builder2.outputs.name }}
      -
        name: Build against builder1
        uses: docker/build-push-action@v2
        with:
          builder: ${{ steps.builder1.outputs.name }}
          target: mytarget1
      -
        name: Build against builder2
        uses: docker/build-push-action@v2
        with:
          builder: ${{ steps.builder2.outputs.name }}
          target: mytarget2

Multi-platform image

name: ci

on:
  push:
    branches: master

jobs:
  multi:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v2
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
      -
        name: Login to DockerHub
        uses: docker/login-action@v1 
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      -
        name: Build and push
        uses: docker/build-push-action@v2
        with:
          context: .
          file: ./Dockerfile
          platforms: linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64,linux/ppc64le,linux/s390x
          push: true
          tags: |
            user/app:latest
            user/app:1.0.0            

Advanced usage

Local registry

For testing purposes you may need to create a local registry to push images into:

Show workflow

name: ci

on:
  push:
    branches: master

jobs:
  local-registry:
    runs-on: ubuntu-latest
    services:
      registry:
        image: registry:2
        ports:
          - 5000:5000
    steps:
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
        with:
          driver-opts: network=host
      -
        name: Build and push to local registry
        uses: docker/build-push-action@v2
        with:
          push: true
          tags: localhost:5000/name/app:latest
      -
        name: Inspect
        run: |
          docker buildx imagetools inspect localhost:5000/name/app:latest          

Leverage GitHub cache

You can leverage GitHub cache using actions/cache with this action:

Show workflow

name: ci

on:
  push:
    branches: master

jobs:
  github-cache:
    runs-on: ubuntu-latest
    steps:
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
      -
        name: Cache Docker layers
        uses: actions/cache@v2
        with:
          path: /tmp/.buildx-cache
          key: ${{ runner.os }}-buildx-${{ github.sha }}
          restore-keys: |
            ${{ runner.os }}-buildx-            
      -
        name: Login to DockerHub
        uses: docker/login-action@v1 
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      -
        name: Build and push
        uses: docker/build-push-action@v2
        with:
          push: true
          tags: user/app:latest
          cache-from: type=local,src=/tmp/.buildx-cache
          cache-to: type=local,dest=/tmp/.buildx-cache

Complete workflow

If you come from v1 and you want an "automatic" tag management through Git reference and OCI Image Format Specification for labels, you will have to do it in a dedicated step for now.

The following workflow with the Prepare step will generate some outputs to handle tags and labels based on GitHub actions events. This is just an example to show many cases that you might want to use:

Show workflow

name: ci

on:
  schedule:
    - cron: '0 10 * * *' # everyday at 10am
  push:
    branches:
      - '**'
    tags:
      - 'v*.*.*'
  pull_request:

jobs:
  docker:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v2
      -
        name: Prepare
        id: prep
        run: |
          DOCKER_IMAGE=name/app
          VERSION=noop
          if [ "${{ github.event_name }}" = "schedule" ]; then
            VERSION=nightly
          elif [[ $GITHUB_REF == refs/tags/* ]]; then
            VERSION=${GITHUB_REF#refs/tags/}
          elif [[ $GITHUB_REF == refs/heads/* ]]; then
            VERSION=$(echo ${GITHUB_REF#refs/heads/} | sed -r 's#/+#-#g')
            if [ "${{ github.event.repository.default_branch }}" = "$VERSION" ]; then
              VERSION=edge
            fi
          elif [[ $GITHUB_REF == refs/pull/* ]]; then
            VERSION=pr-${{ github.event.number }}
          fi
          TAGS="${DOCKER_IMAGE}:${VERSION}"
          if [[ $VERSION =~ ^v[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
            MINOR=${VERSION%.*}
            MAJOR=${MINOR%.*}
            TAGS="$TAGS,${DOCKER_IMAGE}:${MINOR},${DOCKER_IMAGE}:${MAJOR},${DOCKER_IMAGE}:latest"
          elif [ "${{ github.event_name }}" = "push" ]; then
            TAGS="$TAGS,${DOCKER_IMAGE}:sha-${GITHUB_SHA::8}"
          fi
          echo ::set-output name=version::${VERSION}
          echo ::set-output name=tags::${TAGS}
          echo ::set-output name=created::$(date -u +'%Y-%m-%dT%H:%M:%SZ')          
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
      -
        name: Login to DockerHub
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v1 
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      -
        name: Build and push
        id: docker_build
        uses: docker/build-push-action@v2
        with:
          context: .
          file: ./Dockerfile
          platforms: linux/amd64,linux/arm64,linux/386
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.prep.outputs.tags }}
          labels: |
            org.opencontainers.image.title=${{ github.event.repository.name }}
            org.opencontainers.image.description=${{ github.event.repository.description }}
            org.opencontainers.image.url=${{ github.event.repository.html_url }}
            org.opencontainers.image.source=${{ github.event.repository.clone_url }}
            org.opencontainers.image.version=${{ steps.prep.outputs.version }}
            org.opencontainers.image.created=${{ steps.prep.outputs.created }}
            org.opencontainers.image.revision=${{ github.sha }}
            org.opencontainers.image.licenses=${{ github.event.repository.license.spdx_id }}            

Event	Ref	Commit SHA	Docker Tag	Pushed
schedule			nightly	Yes
pull_request	refs/pull/2/merge	a123b57	pr-2	No
push	refs/heads/<default_branch>	676cae2	sha-676cae2, edge	Yes
push	refs/heads/dev	cf20257	sha-cf20257, dev	Yes
push	refs/heads/my/branch	a5df687	sha-a5df687, my-branch	Yes
push tag	refs/tags/v1.2.3		v1.2.3, v1.2, v1, latest	Yes

Update DockerHub repo description

You can update the Docker Hub repository description using a third-party action called Docker Hub Description with this action:

Show workflow

name: ci

on:
  push:
    branches: master

jobs:
  main:
    runs-on: ubuntu-latest
    steps:
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
      -
        name: Login to DockerHub
        uses: docker/login-action@v1 
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      -
        name: Build and push
        uses: docker/build-push-action@v2
        with:
          push: true
          tags: user/app:latest
      -
        name: Update repo description
        uses: peter-evans/dockerhub-description@v2
        env:
          DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
          DOCKERHUB_PASSWORD: ${{ secrets.DOCKERHUB_PASSWORD }}
          DOCKERHUB_REPOSITORY: user/app

Customizing

inputs

Following inputs can be used as step.with keys

Name	Type	Description
builder	String	Builder instance (see setup-buildx action)
context	String	Build's context is the set of files located in the specified PATH or URL (default Git context)
file	String	Path to the Dockerfile (default Dockerfile)
build-args	List	List of build-time variables
labels	List	List of metadata for an image
tags	List	List of tags
pull	Bool	Always attempt to pull a newer version of the image (default false)
target	String	Sets the target stage to build
allow	List	List of extra privileged entitlement (eg. network.host,security.insecure)
no-cache	Bool	Do not use cache when building the image (default false)
platforms	List	List of target platforms for build
load	Bool	Load is a shorthand for --output=type=docker (default false)
push	Bool	Push is a shorthand for --output=type=registry (default false)
outputs	CSV	List of output destinations (format: type=local,dest=path)
cache-from	CSV	List of external cache sources (eg. type=local,src=path/to/dir)
cache-to	CSV	List of cache export destinations (eg. type=local,dest=path/to/dir)
secrets	CSV	List of secrets to expose to the build (eg. key=value, GIT_AUTH_TOKEN=mytoken)

List type can be a comma or newline-delimited string

tags: name/app:latest,name/app:1.0.0

tags: |
  name/app:latest
  name/app:1.0.0  

CSV type must be a newline-delimited string

cache-from: user/app:cache

cache-from: |
  user/app:cache
  type=local,src=path/to/dir  

outputs

Following outputs are available

Name	Type	Description
digest	String	Image content-addressable identifier also called a digest

Troubleshooting

See TROUBLESHOOTING.md

Keep up-to-date with GitHub Dependabot

Since Dependabot has native GitHub Actions support, to enable it on your GitHub repo all you need to do is add the .github/dependabot.yml file:

version: 2
updates:
  # Maintain dependencies for GitHub Actions
  - package-ecosystem: "github-actions"
    directory: "/"
    schedule:
      interval: "daily"

Limitation

This action is only available for Linux virtual environments.