docker-build-push/docs/advanced/cache.md

# Cache

* [Registry cache](#registry-cache)
* [GitHub cache](#github-cache)

> More info about buildx cache: https://github.com/docker/buildx/blob/master/docs/reference/buildx_build.md#cache-from

## Registry cache

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

```yaml
name: ci

on:
  push:
    branches:
      - 'master'

jobs:
  docker:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v2
      -
        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: .
          push: true
          tags: user/app:latest
          cache-from: type=registry,ref=user/app:latest
          cache-to: type=inline
```

## GitHub cache

> :warning: At the moment caches are copied over the existing cache so it [keeps growing](https://github.com/docker/build-push-action/issues/252).
> The `Move cache` step is used as a temporary fix (see https://github.com/moby/buildkit/issues/1896).

> :rocket: There is a new cache backend using GitHub cache being developed that will lighten your workflow.
> More info: https://github.com/docker/buildx/pull/535

You can leverage [GitHub cache](https://docs.github.com/en/actions/configuring-and-managing-workflows/caching-dependencies-to-speed-up-workflows)
using [actions/cache](https://github.com/actions/cache) with this action:

```yaml
name: ci

on:
  push:
    branches:
      - 'master'

jobs:
  docker:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v2
      -
        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:
          context: .
          push: true
          tags: user/app:latest
          cache-from: type=local,src=/tmp/.buildx-cache
          cache-to: type=local,dest=/tmp/.buildx-cache-new
      -
        # 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
```