docker-build-push/README.md

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[![CI workflow](https://img.shields.io/github/workflow/status/docker/build-push-action/ci?label=ci&logo=github&style=flat-square)](https://github.com/docker/build-push-action/actions?workflow=ci)
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## About

GitHub Action to build and push Docker images with [Buildx](https://github.com/docker/buildx).

> :bulb: See also:
> * [login](https://github.com/docker/login-action) action
> * [setup-buildx](https://github.com/docker/setup-buildx-action) action
> * [setup-qemu](https://github.com/docker/setup-qemu-action) action

![Screenshot](.github/build-push-action.png)

___

* [Usage](#usage)
  * [Git context](#git-context)
  * [Path context](#path-context)
  * [Isolated builders](#isolated-builders)
  * [Multi-platform image](#multi-platform-image)
* [Advanced usage](#advanced-usage)
  * [Local registry](#local-registry)
  * [Leverage GitHub cache](#leverage-github-cache)
  * [Complete workflow](#complete-workflow)
  * [Update DockerHub repo description](#update-dockerhub-repo-description)
* [Customizing](#customizing)
  * [inputs](#inputs)
  * [outputs](#outputs)
* [Troubleshooting](#troubleshooting)
* [Keep up-to-date with GitHub Dependabot](#keep-up-to-date-with-github-dependabot)
* [Limitation](#limitation)

## Usage

This action uses our [setup-buildx](https://github.com/docker/setup-buildx-action) action that extends the
`docker build` command named [buildx](https://github.com/docker/buildx) with the full support of the features
provided by [Moby BuildKit](https://github.com/moby/buildkit) builder toolkit. This includes multi-arch build,
build-secrets, remote cache, etc. and different builder deployment/namespacing options.

### Git context

The default behavior of this action is to use the [Git context invoked by your workflow](https://github.com/docker/build-push-action/blob/master/src/context.ts#L35).

```yaml
name: ci

on:
  push:
    branches: master

jobs:
  main:
    runs-on: ubuntu-latest
    steps:
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      -
        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
        id: docker_build
        uses: docker/build-push-action@v2
        with:
          push: true
          tags: user/app:latest
      -
        name: Image digest
        run: echo ${{ steps.docker_build.outputs.digest }}
```

Building from current repository automatically uses the [GitHub Token](https://help.github.com/en/actions/configuring-and-managing-workflows/authenticating-with-the-github_token)
as provided by `secrets` so it does not need to be passed. But if you want to authenticate against another private
repository, you have to use a secret named `GIT_AUTH_TOKEN` to be able to authenticate against it with buildx:

```yaml
      -
        name: Build and push
        id: docker_build
        uses: docker/build-push-action@v2
        with:
          push: true
          tags: user/app:latest
          secrets: |
            GIT_AUTH_TOKEN=${{ secrets.MYTOKEN }}
```

> :warning: Subdir for Git context is [not yet supported](https://github.com/docker/build-push-action/issues/120).
> For the moment you can use the [path context](#path-context).

### Path context

You can also use the `PATH` context alongside the [`actions/checkout`](https://github.com/actions/checkout/) action.

```yaml
name: ci

on:
  push:
    branches: master

jobs:
  path-context:
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v2
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      -
        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: .
          file: ./Dockerfile
          platforms: linux/amd64,linux/arm64,linux/386
          push: true
          tags: user/app:latest
```

### Isolated builders

```yaml
name: ci

on:
  push:
    branches: master

jobs:
  multi-builders:
    runs-on: ubuntu-latest
    steps:
      -
        uses: docker/setup-buildx-action@v1
        id: builder1
      -
        uses: docker/setup-buildx-action@v1
        id: builder2
      -
        name: Builder 1 name
        run: echo ${{ steps.builder1.outputs.name }}
      -
        name: Builder 2 name
        run: echo ${{ steps.builder2.outputs.name }}
      -
        name: Build against builder1
        uses: docker/build-push-action@v2
        with:
          builder: ${{ steps.builder1.outputs.name }}
          target: mytarget1
      -
        name: Build against builder2
        uses: docker/build-push-action@v2
        with:
          builder: ${{ steps.builder2.outputs.name }}
          target: mytarget2
```

### Multi-platform image

```yaml
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@v1
      -
        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: .
          file: ./Dockerfile
          platforms: linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64,linux/ppc64le,linux/s390x
          push: true
          tags: |
            user/app:latest
            user/app:1.0.0
```

## Advanced usage

### Local registry

For testing purposes you may need to create a [local registry](https://hub.docker.com/_/registry) to push images into:

<details>
  <summary><b>Show workflow</b></summary>
  
  ```yaml
  name: ci

  on:
    push:
      branches: master

  jobs:
    local-registry:
      runs-on: ubuntu-latest
      services:
        registry:
          image: registry:2
          ports:
            - 5000:5000
      steps:
        -
          name: Set up QEMU
          uses: docker/setup-qemu-action@v1
        -
          name: Set up Docker Buildx
          uses: docker/setup-buildx-action@v1
          with:
            driver-opts: network=host
        -
          name: Build and push to local registry
          uses: docker/build-push-action@v2
          with:
            push: true
            tags: localhost:5000/name/app:latest
        -
          name: Inspect
          run: |
            docker buildx imagetools inspect localhost:5000/name/app:latest
  ```
</details>

### Leverage GitHub cache

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:

<details>
  <summary><b>Show workflow</b></summary>
  
  ```yaml
  name: ci

  on:
    push:
      branches: master

  jobs:
    github-cache:
      runs-on: ubuntu-latest
      steps:
        -
          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:
            push: true
            tags: user/app:latest
            cache-from: type=local,src=/tmp/.buildx-cache
            cache-to: type=local,dest=/tmp/.buildx-cache
  ```
</details>

### Complete workflow

If you come from [`v1`](https://github.com/docker/build-push-action/tree/releases/v1#readme) and you want an
"automatic" tag management through Git reference and [OCI Image Format Specification](https://github.com/opencontainers/image-spec/blob/master/annotations.md)
for labels, you will have to do it in a dedicated step [for now](https://github.com/docker/build-push-action/issues/116).

The following workflow with the `Prepare` step will generate some [outputs](https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#jobsjobs_idoutputs)
to handle tags and labels based on GitHub actions events. This is just an example to show many cases that you
might want to use:

<details>
  <summary><b>Show workflow</b></summary>
  
  ```yaml
  name: ci

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

  jobs:
    docker:
      runs-on: ubuntu-latest
      steps:
        -
          name: Checkout
          uses: actions/checkout@v2
        -
          name: Prepare
          id: prep
          run: |
            DOCKER_IMAGE=name/app
            VERSION=noop
            if [ "${{ github.event_name }}" = "schedule" ]; then
              VERSION=nightly
            elif [[ $GITHUB_REF == refs/tags/* ]]; then
              VERSION=${GITHUB_REF#refs/tags/}
            elif [[ $GITHUB_REF == refs/heads/* ]]; then
              VERSION=$(echo ${GITHUB_REF#refs/heads/} | sed -r 's#/+#-#g')
              if [ "${{ github.event.repository.default_branch }}" = "$VERSION" ]; then
                VERSION=edge
              fi
            elif [[ $GITHUB_REF == refs/pull/* ]]; then
              VERSION=pr-${{ github.event.number }}
            fi
            TAGS="${DOCKER_IMAGE}:${VERSION}"
            if [[ $VERSION =~ ^v[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
              MINOR=${VERSION%.*}
              MAJOR=${MINOR%.*}
              TAGS="$TAGS,${DOCKER_IMAGE}:${MINOR},${DOCKER_IMAGE}:${MAJOR},${DOCKER_IMAGE}:latest"
            elif [ "${{ github.event_name }}" = "push" ]; then
              TAGS="$TAGS,${DOCKER_IMAGE}:sha-${GITHUB_SHA::8}"
            fi
            echo ::set-output name=version::${VERSION}
            echo ::set-output name=tags::${TAGS}
            echo ::set-output name=created::$(date -u +'%Y-%m-%dT%H:%M:%SZ')
        -
          name: Set up QEMU
          uses: docker/setup-qemu-action@v1
        -
          name: Set up Docker Buildx
          uses: docker/setup-buildx-action@v1
        -
          name: Login to DockerHub
          if: github.event_name != 'pull_request'
          uses: docker/login-action@v1 
          with:
            username: ${{ secrets.DOCKERHUB_USERNAME }}
            password: ${{ secrets.DOCKERHUB_TOKEN }}
        -
          name: Build and push
          id: docker_build
          uses: docker/build-push-action@v2
          with:
            context: .
            file: ./Dockerfile
            platforms: linux/amd64,linux/arm64,linux/386
            push: ${{ github.event_name != 'pull_request' }}
            tags: ${{ steps.prep.outputs.tags }}
            labels: |
              org.opencontainers.image.title=${{ github.event.repository.name }}
              org.opencontainers.image.description=${{ github.event.repository.description }}
              org.opencontainers.image.url=${{ github.event.repository.html_url }}
              org.opencontainers.image.source=${{ github.event.repository.clone_url }}
              org.opencontainers.image.version=${{ steps.prep.outputs.version }}
              org.opencontainers.image.created=${{ steps.prep.outputs.created }}
              org.opencontainers.image.revision=${{ github.sha }}
              org.opencontainers.image.licenses=${{ github.event.repository.license.spdx_id }}
  ```
</details>

| Event           | Ref                           | Commit SHA | Docker Tag                         | Pushed |
|-----------------|-------------------------------|------------|------------------------------------|--------|
| `schedule`      |                               |            | `nightly`                          | Yes    |
| `pull_request`  | `refs/pull/2/merge`           | `a123b57`  | `pr-2`                             | No     |
| `push`          | `refs/heads/<default_branch>` | `676cae2`  | `sha-676cae2`, `edge`              | Yes    |
| `push`          | `refs/heads/dev`              | `cf20257`  | `sha-cf20257`, `dev`               | Yes    |
| `push`          | `refs/heads/my/branch`        | `a5df687`  | `sha-a5df687`, `my-branch`         | Yes    |
| `push tag`      | `refs/tags/v1.2.3`            |            | `v1.2.3`, `v1.2`, `v1`, `latest`   | Yes    |

### Update DockerHub repo description

You can update the [Docker Hub repository description](https://docs.docker.com/docker-hub/repos/) using
a third-party action called [Docker Hub Description](https://github.com/peter-evans/dockerhub-description)
with this action:

<details>
  <summary><b>Show workflow</b></summary>
  
  ```yaml
  name: ci

  on:
    push:
      branches: master

  jobs:
    main:
      runs-on: ubuntu-latest
      steps:
        -
          name: Set up QEMU
          uses: docker/setup-qemu-action@v1
        -
          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:
            push: true
            tags: user/app:latest
        -
          name: Update repo description
          uses: peter-evans/dockerhub-description@v2
          env:
            DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
            DOCKERHUB_PASSWORD: ${{ secrets.DOCKERHUB_PASSWORD }}
            DOCKERHUB_REPOSITORY: user/app
  ```
</details>

## Customizing

### inputs

Following inputs can be used as `step.with` keys

| Name                | Type    | Description                        |
|---------------------|---------|------------------------------------|
| `builder`           | String  | Builder instance (see [setup-buildx](https://github.com/docker/setup-buildx-action) action) |
| `context`           | String  | Build's context is the set of files located in the specified [`PATH` or `URL`](https://docs.docker.com/engine/reference/commandline/build/) (default [Git context](#git-context)) |
| `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](https://github.com/docker/buildx#--allowentitlement) (eg. `network.host,security.insecure`) |
| `no-cache`          | Bool    | Do not use cache when building the image (default `false`) |
| `platforms`         | List    | List of [target platforms](https://github.com/docker/buildx#---platformvaluevalue) for build |
| `load`              | Bool    | [Load](https://github.com/docker/buildx#--load) is a shorthand for `--output=type=docker` (default `false`) |
| `push`              | Bool    | [Push](https://github.com/docker/buildx#--push) is a shorthand for `--output=type=registry` (default `false`) |
| `outputs`           | CSV     | List of [output destinations](https://github.com/docker/buildx#-o---outputpath-typetypekeyvalue) (format: `type=local,dest=path`) |
| `cache-from`        | CSV     | List of [external cache sources](https://github.com/docker/buildx#--cache-fromnametypetypekeyvalue) (eg. `type=local,src=path/to/dir`) |
| `cache-to`          | CSV     | List of [cache export destinations](https://github.com/docker/buildx#--cache-tonametypetypekeyvalue) (eg. `type=local,dest=path/to/dir`) |
| `secrets`           | CSV     | List of secrets to expose to the build (eg. `key=value`, `GIT_AUTH_TOKEN=mytoken`) |

> `List` type can be a comma or newline-delimited string
> ```yaml
> tags: name/app:latest,name/app:1.0.0
> ```
> ```yaml
> tags: |
>   name/app:latest
>   name/app:1.0.0
> ```

> `CSV` type must be a newline-delimited string
> ```yaml
> cache-from: user/app:cache
> ```
> ```yaml
> 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 |

## Troubleshooting

See [TROUBLESHOOTING.md](TROUBLESHOOTING.md)

## Keep up-to-date with GitHub Dependabot

Since [Dependabot](https://docs.github.com/en/github/administering-a-repository/keeping-your-actions-up-to-date-with-github-dependabot)
has [native GitHub Actions support](https://docs.github.com/en/github/administering-a-repository/configuration-options-for-dependency-updates#package-ecosystem),
to enable it on your GitHub repo all you need to do is add the `.github/dependabot.yml` file:

```yaml
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](https://help.github.com/en/articles/virtual-environments-for-github-actions#supported-virtual-environments-and-hardware-resources).