Custom Grafana Alloy Docker Image (GHCR)

This repository builds a custom Docker image based on the official Grafana Alloy image, injecting your own configuration, and pushes it to GitHub Container Registry (GHCR).

How it works

• The Dockerfile uses the official Alloy image as a base and copies in your custom configuration.
• A GitHub Actions workflow checks for new releases of the official Alloy image (on push to main, on a schedule, or manually).
• If a new version is found, it automatically builds and pushes a new image with your configuration to GHCR.

Workflow Triggers

The workflow runs on:

• Pushes to the main branch
• A daily schedule (6am UTC)
• Manual dispatch via the GitHub Actions UI

How the Workflow Works

• Fetch latest upstream tag:
  • Uses a shell step with curl and jq to fetch the latest stable tag from Docker Hub for grafana/alloy.
• Compare with last built tag:
  • If the tag is new, proceeds to build and push.
• Log in to GHCR:
  • Uses docker/login-action to authenticate to GitHub Container Registry with the built-in GITHUB_TOKEN.
• Build and push:
  • Uses docker/build-push-action to build the image with the correct base tag and push to ghcr.io/<owner>/alloy-custom:<tag>.
• Update last built tag:
  • Stores the last built tag in .last_built_tag and commits it to the repository.

Usage

1. Place your Alloy configuration in alloy-config.yaml.
2. The image will be built and published to GHCR as ghcr.io/<your-org-or-username>/alloy-custom:<upstream-tag>.

Manual build

To build and run locally:

docker build --build-arg ALLOY_TAG=<tag> -t my-alloy:local .
docker run --rm -it my-alloy:local

GitHub Actions

• The workflow is defined in .github/workflows/rebuild-on-upstream.yml.
• It uses:
  • A shell step to fetch the latest upstream tag with curl and jq.
  • docker/login-action for GHCR authentication.
  • docker/build-push-action to build and push the image.
  • stefanzweifel/git-auto-commit-action to update the last built tag.

Customization

• Edit alloy-config.yaml to change the configuration.
• Edit the Dockerfile if you need to change the config path or add more files.

License

MIT