About

GitHub Action to use Docker Buildx Bake as a high-level build command.

---

• Usage
  • Path context
  • Git context
• Customizing
  • inputs
  • outputs
• Subactions
  • list-targets
• Contributing

Usage

Path context

By default, this action will use the local bake definition (source: .), so you need to use the actions/checkout action to check out the repository.

name: ci

on:
  push:
    branches:
      - 'master'

jobs:
  bake:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v4
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3
      -
        name: Login to DockerHub
        uses: docker/login-action@v3
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      -
        name: Build and push
        uses: docker/bake-action@v4
        with:
          push: true

Git context

Git context can be provided using the source input. This means that you don't need to use the actions/checkout action to check out the repository as BuildKit will do this directly.

name: ci

on:
  push:
    branches:
      - 'master'

jobs:
  bake:
    runs-on: ubuntu-latest
    steps:
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3
      -
        name: Login to DockerHub
        uses: docker/login-action@v3
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      -
        name: Build and push
        uses: docker/bake-action@v4
        with:
          source: "${{ github.server_url }}/${{ github.repository }}.git#${{ github.ref }}"
          push: true

Be careful because any file mutation in the steps that precede the build step will be ignored, including processing of the .dockerignore file since the context is based on the Git reference. However, you can use the Path context alongside the actions/checkout action to remove this restriction.

Default Git context can also be provided using the Handlebars template expression {{defaultContext}}. Here we can use it to provide a subdirectory to the default Git context:

      -
        name: Build and push
        uses: docker/bake-action@v4
        with:
          source: "{{defaultContext}}:mysubdir"
          push: true

Customizing

inputs

The following inputs can be used as step.with keys

List type is a newline-delimited string

set: target.args.mybuildarg=value

set: |
  target.args.mybuildarg=value
  foo*.args.mybuildarg=value

CSV type is a comma-delimited string

targets: default,release

Name	Type	Description
builder	String	Builder instance (see setup-buildx action)
source	String	Context to build from. Can be either local (.) or a remote bake definition
files	List/CSV	List of bake definition files
workdir	String	Working directory of execution
targets	List/CSV	List of bake targets (default target used if empty)
no-cache	Bool	Do not use cache when building the image (default false)
pull	Bool	Always attempt to pull a newer version of the image (default false)
load	Bool	Load is a shorthand for --set=*.output=type=docker (default false)
provenance	Bool/String	Provenance is a shorthand for --set=*.attest=type=provenance
push	Bool	Push is a shorthand for --set=*.output=type=registry (default false)
sbom	Bool/String	SBOM is a shorthand for --set=*.attest=type=sbom
set	List	List of targets values to override (eg: targetpattern.key=value)

outputs

The following outputs are available

Name	Type	Description
metadata	JSON	Build result metadata

Subactions

list-targets

This subaction generates a list of Bake targets that can be used in a GitHub matrix, so you can distribute your builds across multiple runners.

# docker-bake.hcl
group "validate" {
  targets = ["lint", "doctoc"]
}

target "lint" {
  target = "lint"
}

target "doctoc" {
  target = "doctoc"
}

jobs:
  prepare:
    runs-on: ubuntu-latest
    outputs:
      targets: ${{ steps.generate.outputs.targets }}
    steps:
      -
        name: Checkout
        uses: actions/checkout@v4
      -
        name: List targets
        id: generate
        uses: docker/bake-action/subaction/list-targets@v4
        with:
          target: validate

  validate:
    runs-on: ubuntu-latest
    needs:
      - prepare
    strategy:
      fail-fast: false
      matrix:
        target: ${{ fromJson(needs.prepare.outputs.targets) }}
    steps:
      -
        name: Checkout
        uses: actions/checkout@v4
      -
        name: Validate
        uses: docker/bake-action@v4
        with:
          targets: ${{ matrix.target }}

inputs

Name	Type	Description
workdir	String	Working directory to use (defaults to .)
files	List/CSV	List of bake definition files
target	String	The target to use within the bake file

outputs

The following outputs are available

Name	Type	Description
targets	List/CSV	List of extracted targest

Contributing

Want to contribute? Awesome! You can find information about contributing to this project in the CONTRIBUTING.md