Setup Docker Builder Action

This GitHub Action sets up a Docker buildkitd builder with sticky disk cache for improved build performance.

Features

• Sets up buildkitd with a persistent cache stored on a sticky disk
• Automatically mounts the cache at /var/lib/buildkit
• Handles builder lifecycle (start, configure, cleanup)
• Supports multi-platform builds
• Falls back to local builder if Blacksmith setup fails

Usage

- name: Setup Docker Builder
  uses: useblacksmith/setup-docker-builder@v1
  with:
    buildx-version: "v0.23.0" # optional, defaults to v0.23.0
    platforms: "linux/amd64,linux/arm64" # optional
    nofallback: "false" # optional, defaults to false
    github-token: ${{ secrets.GITHUB_TOKEN }} # optional

Inputs

Name	Description	Required	Default
buildx-version	Buildx version (e.g., v0.23.0, latest)	No	v0.23.0
platforms	List of target platforms for build (e.g., linux/amd64,linux/arm64)	No
nofallback	If true, fail the action if Blacksmith builder setup fails	No	false
github-token	GitHub token for GitHub API access	No

Example Workflows

Basic usage with build-push-action

- uses: useblacksmith/setup-docker-builder@v1
- uses: useblacksmith/build-push-action@v1
  with:
    push: true
    tags: user/app:latest

Multiple builds in one job

- uses: useblacksmith/setup-docker-builder@v1

- uses: useblacksmith/build-push-action@v1
  with:
    file: ./Dockerfile.app1
    tags: user/app1:latest

- uses: useblacksmith/build-push-action@v1
  with:
    file: ./Dockerfile.app2
    tags: user/app2:latest

Custom Docker commands

- uses: useblacksmith/setup-docker-builder@v1

- run: docker buildx bake

- run: |
    docker buildx build \
      --platform linux/amd64,linux/arm64 \
      --tag myapp:latest \
      .

How it works

1. The action sets up buildkitd with a sticky disk mounted at /var/lib/buildkit
2. This provides a persistent cache across builds in the same repository
3. The builder is configured as the default for all subsequent Docker commands
4. In the post-action cleanup, the cache is committed and buildkitd is shut down

Requirements

• GitHub Actions runner with Docker installed
• Blacksmith environment variables configured