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GitHub

Dagger can directly interact with GitHub pull requests, making it easy to test the functionality of specific forks or branches of a GitHub repository.

Dagger also supports publishing container images to GitHub Container Registry.

How it works​

GitHub contains a shorthand redirect at the /merge endpoint that allows you to reference the correct branch of a repository from a pull request (PR), without needing to know anything about the fork or branch where the PR came from.

By default, the Dagger Directory type works with both local directories and remote Git repositories. This makes it possible to work with the directory tree at the root of a Git repository or a given branch.

By combining these two features, Dagger users can write Dagger Functions that directly use GitHub pull requests as arguments.

Prerequisites​

  • A GitHub repository

Examples​

Given a Dagger Function called foo that accepts a Directory as argument, you can pass it a GitHub pull request URL as argument like this:

dagger call foo --directory=https://github.com/ORGANIZATION/REPOSITORY#pull/NUMBER/merge

If your GitHub repository contains a Dagger module, you can test the functionality of a specific branch by calling the Dagger module with the corresponding pull request URL, as shown below:

dagger call -m github.com/ORGANIZATION/REPOSITORY@pull/NUMBER/merge --help

You can also use a Dagger Function in a GitHub Actions workflow to publish a container image to GitHub Container Registry.

.github/workflows/dagger.yml
name: dagger
on:
  push:
    branches: [main]

jobs:
  build-publish:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Call Dagger Function to build and publish to ghcr.io
        uses: dagger/dagger-for-github@v6
        with:
          version: "latest"
          verb: call
          module: github.com/daggerverse/dagger-ghcr-demo@v0.1.5
          args: build-and-push --registry=$DOCKER_REGISTRY --image-name=$DOCKER_IMAGE_NAME --username=$DOCKER_USERNAME --password=env:DOCKER_PASSWORD --build-context=github.com/daggerverse/dagger-ghcr-demo
          # assumes the Dagger Cloud token is in
          # a repository secret named DAGGER_CLOUD_TOKEN
          # set via the GitHub UI/CLI
          cloud-token: ${{ secrets.DAGGER_CLOUD_TOKEN }}
        env:
          DOCKER_REGISTRY: ghcr.io
          DOCKER_IMAGE_NAME: ${{ github.repository }}
          DOCKER_USERNAME: ${{ github.actor }}
          # assumes the container registry password is in
          # a repository secret named REGISTRY_PASSWORD
          # set via the GitHub UI/CL
          DOCKER_PASSWORD: ${{ secrets.REGISTRY_PASSWORD }}

Resources​

If you have any questions about additional ways to use GitHub with Dagger, join our Discord and ask your questions in our GitHub channel.

About GitHub​

GitHub is a popular Web-based platform used for version control and collaboration. It allows developers to store and manage their code in repositories, track changes over time, and collaborate with other developers on projects.