About

GitHub Action to build and push Docker images.

💡 See also:

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

---

• Usage
  • Quick start
  • Multi-platform image
  • Git context
  • Leverage GitHub cache
  • Complete workflow
• Customizing
  • inputs
  • outputs
  • environment variables
• 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.

Quick start

name: ci

on:
  push:
    branches: master

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

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@master
        with:
          platforms: all
      -
        name: Set up Docker Buildx
        id: buildx
        uses: docker/setup-buildx-action@master
      -
        name: Login to DockerHub
        uses: docker/login-action@v1 
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}
      -
        name: Build and push
        uses: docker/build-push-action@v2
        with:
          builder: ${{ steps.buildx.outputs.name }}
          context: .
          file: ./Dockerfile
          platforms: linux/amd64,linux/arm64,linux/386
          push: true
          tags: |
            user/app:latest
            user/app:1.0.0            

Git context

You can build from Git directly without actions/checkout action, even in private repositories if your context is a valid Git url:

name: ci

on:
  push:
    branches: master

jobs:
  git-context:
    runs-on: ubuntu-latest
    steps:
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@master
        with:
          platforms: all
      -
        name: Set up Docker Buildx
        id: buildx
        uses: docker/setup-buildx-action@master
        with:
          version: latest
      -
        name: Login to DockerHub
        uses: docker/login-action@v1
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}
      -
        name: Build and push
        uses: docker/build-push-action@v2
        with:
          builder: ${{ steps.buildx.outputs.name }}
          context: "${{ github.repositoryUrl }}#${{ github.ref }}"
          platforms: linux/amd64,linux/arm64,linux/386
          push: true
          tags: |
            name/app:latest
            name/app:1.0.0            
        env:
          GIT_AUTH_TOKEN: ${{ github.token }}

Leverage GitHub cache

You can leverage GitHub cache using @actions/cache with this action.

name: ci

on:
  push:
    branches: master

jobs:
  main:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v2
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@master
        with:
          platforms: all
      -
        name: Set up Docker Buildx
        id: buildx
        uses: docker/setup-buildx-action@master
      -
        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.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}
      -
        name: Build and push
        id: docker_build
        uses: docker/build-push-action@v2
        with:
          builder: ${{ steps.buildx.outputs.name }}
          push: true
          tags: user/app:latest
          cache-from: type=local,src=/tmp/.buildx-cache
          cache-to: type=local,dest=/tmp/.buildx-cache
      -
        name: Image digest
        run: echo ${{ steps.docker_build.outputs.digest }}

Complete workflow

• On pull_request event, Docker image name/app:edge is built.
• On push event, Docker image name/app:edge is built and pushed to DockerHub.
• On schedule event, Docker image name/app:nightly is built and pushed to DockerHub.
• On push tags event, Docker image name/app:<version> and name/app:latest is built and pushed to DockerHub.

name: ci

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

jobs:
  docker:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v2
      -
        name: Prepare
        id: prep
        run: |
          DOCKER_IMAGE=name/app
          VERSION=edge
          if [[ $GITHUB_REF == refs/tags/* ]]; then
            VERSION=${GITHUB_REF#refs/tags/v}
          fi
          if [ "${{ github.event_name }}" = "schedule" ]; then
            VERSION=nightly
          fi
          TAGS="${DOCKER_IMAGE}:${VERSION}"
          if [[ $VERSION =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
            TAGS="$TAGS,${DOCKER_IMAGE}:latest"
          fi
          echo ::set-output name=tags::${TAGS}          
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@master
        with:
          platforms: all
      -
        name: Set up Docker Buildx
        id: buildx
        uses: docker/setup-buildx-action@master
      -
        name: Login to DockerHub
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v1 
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}
      -
        name: Build and push
        id: docker_build
        uses: docker/build-push-action@v2
        with:
          builder: ${{ steps.buildx.outputs.name }}
          context: .
          file: ./Dockerfile
          platforms: linux/amd64,linux/arm64,linux/386
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.prep.outputs.tags }}

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 .)
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. user/app:cache, type=local,src=path/to/dir)
cache-to	CSV	List of cache export destinations (eg. user/app:cache, type=local,dest=path/to/dir)

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

environment variables

Following environment variables can be used as step.env keys

Name	Description
GIT_AUTH_HEADER¹	Raw authorization header to authenticate against git repository
GIT_AUTH_TOKEN¹	x-access-token basic auth to authenticate against git repository

¹ Only used if input.context is a valid git uri.

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.