# Named contexts with GitHub Actions


You can define [additional build contexts](/reference/cli/docker/buildx/build/#build-context),
and access them in your Dockerfile with `FROM name` or `--from=name`. When
Dockerfile defines a stage with the same name it's overwritten.

This can be useful with GitHub Actions to reuse results from other builds or pin
an image to a specific tag in your workflow.

## Pin image to a tag

Replace `alpine:latest` with a pinned one:

```dockerfile
# syntax=docker/dockerfile:1
FROM alpine
RUN echo "Hello World"
```

```yaml
name: ci

on:
  push:

jobs:
  docker:
    runs-on: ubuntu-latest
    steps:
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v4

      - name: Build
        uses: docker/build-push-action@v7
        with:
          build-contexts: |
            alpine=docker-image://alpine:3.23
          tags: myimage:latest
```

## Use image in subsequent steps

By default, the [Docker Setup Buildx](https://github.com/marketplace/actions/docker-setup-buildx)
action uses `docker-container` as a build driver, so built Docker images aren't
loaded automatically.

With named contexts you can reuse the built image:

```dockerfile
# syntax=docker/dockerfile:1
FROM alpine
RUN echo "Hello World"
```

```yaml
name: ci

on:
  push:

jobs:
  docker:
    runs-on: ubuntu-latest
    steps:
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v4
        with:
          driver: docker

      - name: Build base image
        uses: docker/build-push-action@v7
        with:
          context: "{{defaultContext}}:base"
          load: true
          tags: my-base-image:latest

      - name: Build
        uses: docker/build-push-action@v7
        with:
          build-contexts: |
            alpine=docker-image://my-base-image:latest
          tags: myimage:latest
```

## Using with a container builder

As shown in the previous section we are not using the default
[`docker-container` driver](/build/builders/drivers/docker-container/) for building with
named contexts. That's because this driver can't load an image from the Docker
store as it's isolated. To solve this problem you can use a [local registry](/build/ci/github-actions/named-contexts/local-registry/)
to push your base image in your workflow:

```dockerfile
# syntax=docker/dockerfile:1
FROM alpine
RUN echo "Hello World"
```

```yaml
name: ci

on:
  push:

jobs:
  docker:
    runs-on: ubuntu-latest
    services:
      registry:
        image: registry:3
        ports:
          - 5000:5000
    steps:
      - name: Set up QEMU
        uses: docker/setup-qemu-action@v4

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v4
        with:
          # network=host driver-opt needed to push to local registry
          driver-opts: network=host

      - name: Build base image
        uses: docker/build-push-action@v7
        with:
          context: "{{defaultContext}}:base"
          tags: localhost:5000/my-base-image:latest
          push: true

      - name: Build
        uses: docker/build-push-action@v7
        with:
          build-contexts: |
            alpine=docker-image://localhost:5000/my-base-image:latest
          tags: myimage:latest
```