Cache management with GitHub Actions

もくじ

This page contains examples on using the cache storage backends with GitHub Actions.

メモ

See Cache storage backends for more details about cache storage backends.

Inline cache

In most cases you want to use the inline cache exporter. However, note that the inline cache exporter only supports min cache mode. To use max cache mode, push the image and the cache separately using the registry cache exporter with the cache-to option, as shown in the registry cache example.

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

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          push: true
          tags: user/app:latest
          cache-from: type=registry,ref=user/app:latest
          cache-to: type=inline

Registry cache

You can import/export cache from a cache manifest or (special) image configuration on the registry with the registry cache exporter.

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

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          push: true
          tags: user/app:latest
          cache-from: type=registry,ref=user/app:buildcache
          cache-to: type=registry,ref=user/app:buildcache,mode=max

GitHub cache

Cache backend API

試験的

This cache exporter is experimental. Please provide feedback on the BuildKit repository if you experience any issues.

The GitHub Actions cache exporter backend uses the GitHub Cache API to fetch and upload cache blobs. That's why you should only use this cache backend in a GitHub Action workflow, as the url ($ACTIONS_CACHE_URL) and token ($ACTIONS_RUNTIME_TOKEN) attributes only get populated in a workflow context.

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

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          push: true
          tags: user/app:latest
          cache-from: type=gha
          cache-to: type=gha,mode=max

Cache mounts

BuildKit doesn't preserve cache mounts in the GitHub Actions cache by default. If you wish to put your cache mounts into GitHub Actions cache and reuse it between builds, you can use a workaround provided by reproducible-containers/buildkit-cache-dance.

This GitHub Action creates temporary containers to extract and inject the cache mount data with your Docker build steps.

The following example shows how to use this workaround with a Go project.

Example Dockerfile in build/package/Dockerfile

FROM golang:1.21.1-alpine as base-build

WORKDIR /build
RUN go env -w GOMODCACHE=/root/.cache/go-build

COPY go.mod go.sum ./
RUN --mount=type=cache,target=/root/.cache/go-build go mod download

COPY ./src ./
RUN --mount=type=cache,target=/root/.cache/go-build go build -o /bin/app /build/src
...

Example CI action

name: ci

on:
  push:

jobs:
  build:
    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: Docker meta
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: user/app
          tags: |
            type=ref,event=branch
            type=ref,event=pr
            type=semver,pattern={{version}}
            type=semver,pattern={{major}}.{{minor}}            

      - name: Go Build Cache for Docker
        uses: actions/cache@v4
        with:
          path: go-build-cache
          key: ${{ runner.os }}-go-build-cache-${{ hashFiles('**/go.sum') }}

      - name: Inject go-build-cache
        uses: reproducible-containers/buildkit-cache-dance@4b2444fec0c0fb9dbf175a96c094720a692ef810 # v2.1.4
        with:
          cache-source: go-build-cache

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          cache-from: type=gha
          cache-to: type=gha,mode=max
          file: build/package/Dockerfile
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          platforms: linux/amd64,linux/arm64

For more information about this workaround, refer to the GitHub repository.

Local cache

警告

At the moment, old cache entries aren't deleted, so the cache size keeps growing. The following example uses the Move cache step as a workaround (see moby/buildkit#1896 for more info).

You can also leverage GitHub cache using the actions/cache and local cache exporter with this action:

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

      - name: Cache Docker layers
        uses: actions/cache@v4
        with:
          path: /tmp/.buildx-cache
          key: ${{ runner.os }}-buildx-${{ github.sha }}
          restore-keys: |
            ${{ runner.os }}-buildx-            

      - name: Build and push
        uses: docker/build-push-action@v6
        with:
          push: true
          tags: user/app:latest
          cache-from: type=local,src=/tmp/.buildx-cache
          cache-to: type=local,dest=/tmp/.buildx-cache-new,mode=max

      - # Temp fix
        # https://github.com/docker/build-push-action/issues/252
        # https://github.com/moby/buildkit/issues/1896
        name: Move cache
        run: |
          rm -rf /tmp/.buildx-cache
          mv /tmp/.buildx-cache-new /tmp/.buildx-cache