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guides: docker build github actions primer
Signed-off-by: David Karlsson <[email protected]>
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‎content/guides/gha.md‎

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---
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title: Introduction to GitHub Actions with Docker
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linkTitle: GitHub Actions and Docker
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summary: |
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Learn how to automate image build and push with GitHub Actions.
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params:
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tags: [devops]
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time: 10 minutes
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---
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This guide provides an introduction to building CI pipelines using Docker and
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GitHub Actions. You will learn how to use Docker's official GitHub Actions to
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build your application as a Docker image and push it to Docker Hub. By the end
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of the guide, you'll have a simple, functional GitHub Actions configuration for
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Docker builds. Use it as-is, or extend it further to fit your needs.
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## Prerequisites
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If you want to follow along with the guide, ensure you have the following:
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- A Docker account.
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- Familiarity with Dockerfiles.
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This guide assumes basic knowledge of Docker concepts but provides explanations
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for using Docker in GitHub Actions workflows.
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## Get the sample app
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This guide is project-agnostic and assumes you have an application with a
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Dockerfile.
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If you need a sample project to follow along, you can use [this sample
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application](https://github.com/dvdksn/rpg-name-generator.git), which includes
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a Dockerfile for building a containerized version of the app. Alternatively,
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use your own GitHub project or create a new repository from the template.
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{{% dockerfile.inline %}}
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{{ $data := resources.GetRemote "https://raw.githubusercontent.com/dvdksn/rpg-name-generator/refs/heads/main/Dockerfile" }}
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```dockerfile {collapse=true}
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{{ $data.Content }}
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```
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{{% /dockerfile.inline %}}
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## Configure your GitHub repository
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The workflow in this guide pushes the image you build to Docker Hub. To do
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that, you must authenticate with your Docker credentials (username and access
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token) as part of the GitHub Actions workflow.
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For instructions on how to create a Docker access token, see
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[Create and manage access tokens](/manuals/security/for-developers/access-tokens.md).
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Once you have your Docker credentials ready, add the credentials to your GitHub
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repository so you can use them in GitHub Actions:
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1. Open your repository's **Settings**.
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2. Under **Security**, go to **Secrets and variables > Actions**.
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3. Under **Secrets**, create a new repository secret named `DOCKER_PASSWORD`,
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containing your Docker access token.
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4. Next, under **Variables**, create a `DOCKER_USERNAME` repository variable
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containing your Docker Hub username.
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## Set up your GitHub Actions workflow
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GitHub Actions workflows define a series of steps to automate tasks, such as
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building and pushing Docker images, in response to triggers like commits or
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pull requests. In this guide, the workflow focuses on automating Docker builds
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and testing, ensuring your containerized application works correctly before
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publishing it.
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Create a file named `docker-ci.yml` in the `.github/workflows/` directory of
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your repository. Start with the basic workflow configuration:
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```yaml
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name: Build and Push Docker Image
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on:
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push:
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branches:
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- main
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pull_request:
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```
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This configuration runs the workflow on pushes to the main branch and on pull
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requests. By including both triggers, you can ensure that the image builds
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correctly for a pull request before it's merged.
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## Extract metadata for tags and annotations
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For the first step in your workflow, use the `docker/metadata-action` to
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generate metadata for your image. This action extracts information about your
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Git repository, such as branch names and commit SHAs, and generates image
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metadata such as tags and annotations.
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Add the following YAML to your workflow file:
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```yaml
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jobs:
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build:
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runs-on: ubuntu-latest
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steps:
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- name: Checkout
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uses: actions/checkout@v4
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- name: Extract Docker image metadata
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id: meta
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uses: docker/metadata-action@v5
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with:
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images: ${{ vars.DOCKER_USERNAME }}/my-image
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```
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These steps prepare metadata to tag and annotate your images during the build
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and push process.
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- The **Checkout** step clones the Git repository.
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- The **Extract Docker image metadata** step extracts Git metadata and
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generates image tags and annotations for the Docker build.
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## Authenticate to your registry
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Before you build the image, authenticate to your registry to ensure that you
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can push your built image to the registry.
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To authenticate with Docker Hub, add the following step to your workflow:
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```yaml
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- name: Log in to Docker Hub
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uses: docker/login-action@v3
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with:
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username: ${{ vars.DOCKER_USERNAME }}
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password: ${{ secrets.DOCKER_PASSWORD }}
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```
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This step uses the Docker credentials [configured in the repository settings](#configure-your-github-repository).
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## Build and push the image
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Finally, build the final production image and push it to your registry. The
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following configuration builds the image and pushes it directly to a registry.
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```yaml
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- name: Build and push Docker image
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uses: docker/build-push-action@v6
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with:
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push: ${{ github.event_name != 'pull_request' }}
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tags: ${{ steps.meta.outputs.tags }}
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annotations: ${{ steps.meta.outputs.annotations }}
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```
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In this configuration:
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- `push: ${{ github.event_name != 'pull_request' }}` ensures that images are
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only pushed when the event is not a pull request. This way, the workflow
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builds and tests images for pull requests but only pushes images for commits
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to the main branch.
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- `tags` and `annotations` use the outputs from the metadata action to apply
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consistent tags and [annotations](/manuals/build/metadata/annotations.md) to
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the image automatically.
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## Attestations
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SBOM (Software Bill of Materials) and provenance attestations improve security
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and traceability, ensuring your images meet modern software supply chain
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requirements.
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With a small amount of additional configuration, you can configure
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`docker/build-push-action` to generate Software Bill of Materials (SBOM) and
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provenance attestations for the image, at build-time.
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To generate this additional metadata, you need to make two changes to your
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workflow:
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- Before the build step, add a step that uses `docker/setup-buildx-action`.
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This action configures your Docker build client with additional capabilities
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that the default client doesn't support.
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- Then, update the **Build and push Docker image** step to also enable SBOM and
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provenance attestations.
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Here's the updated snippet:
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```yaml
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- name: Set up Docker Buildx
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uses: docker/setup-buildx-action@v3
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- name: Build and push Docker image
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uses: docker/build-push-action@v6
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with:
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push: ${{ github.event_name != 'pull_request' }}
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tags: ${{ steps.meta.outputs.tags }}
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annotations: ${{ steps.meta.outputs.annotations }}
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provenance: true
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sbom: true
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```
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For more details about attestations, refer to
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[the documentation](/manuals/build/metadata/attestations/_index.md).
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## Conclusion
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With all the steps outlined in the previous section, here's the full workflow
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configuration:
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```yaml
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name: Build and Push Docker Image
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on:
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push:
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branches:
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- main
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pull_request:
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jobs:
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build:
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runs-on: ubuntu-latest
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steps:
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- name: Checkout
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uses: actions/checkout@v4
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- name: Extract Docker image metadata
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id: meta
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uses: docker/metadata-action@v5
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with:
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images: ${{ vars.DOCKER_USERNAME }}/my-image
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- name: Log in to Docker Hub
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uses: docker/login-action@v3
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with:
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username: ${{ vars.DOCKER_USERNAME }}
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password: ${{ secrets.DOCKER_PASSWORD }}
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- name: Set up Docker Buildx
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uses: docker/setup-buildx-action@v3
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- name: Build and push Docker image
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uses: docker/build-push-action@v6
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with:
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push: ${{ github.event_name != 'pull_request' }}
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tags: ${{ steps.meta.outputs.tags }}
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annotations: ${{ steps.meta.outputs.annotations }}
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provenance: true
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sbom: true
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```
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This workflow implements best practices for building and pushing Docker images
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using GitHub Actions. This configuration can be used as-is or extended with
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additional features based on your project's needs, such as
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[multi-platform](/manuals/build/building/multi-platform.md).
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### Further reading
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- Learn more about advanced configurations and examples in the [Docker Build GitHub Actions](/manuals/build/ci/github-actions/_index.md) section.
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- For more complex build setups, you may want to consider [Bake](/manuals/build/bake/_index.md). (See also the [Mastering Buildx Bake guide](/guides/bake/index.md).)
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- Learn about Docker's managed build service, designed for faster, multi-platform builds, see [Docker Build Cloud](/guides/docker-build-cloud/_index.md).

‎content/manuals/build/ci/github-actions/_index.md‎

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---
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title: Introduction to GitHub Actions
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title: Docker Build GitHub Actions
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linkTitle: GitHub Actions
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description: Docker maintains a set of official GitHub Actions for building Docker images.
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keywords: ci, github actions, gha, build, introduction, tutorial

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