Chainguard Container for gha-runner-scale-set-controller

Kubernetes controller for GitHub Actions self-hosted runners

Chainguard Containers are regularly-updated, secure-by-default container images.

Download this Container Image

For those with access, this container image is available on cgr.dev:

docker pull cgr.dev/ORGANIZATION/gha-runner-scale-set-controller:latest

Be sure to replace the ORGANIZATION placeholder with the name used for your organization's private repository within the Chainguard Registry.

Usage

This document outlines how to test our gha-runner-scale-set-controller image. You can set up ARC on Kubernetes using Helm, then create and run a workflow that uses runner scale sets.

For more information about runner scale sets, you should refer to the official documentation, Quickstart for Actions Runner Controller.

Prerequisites

You can find a detailed list of prerequisites in the official documentation, (here)[https://docs.github.com/en/actions/hosting-your-own-runners/managing-self-hosted-runners-with-actions-runner-controller/quickstart-for-actions-runner-controller#prerequisites).

But for the sake of simplicity, all you need is:

• A Kubernetes cluster
• Helm 3
• A GitHub repository with a workflow that uses runner scale sets

that's all.

Testing

To test the gha-runner-scale-set-controller image, you can follow these steps:

1. Install the Actions Runner Controller on your Kubernetes cluster using Helm. You can find the installation instructions here.

NAMESPACE="arc-systems"
helm install arc \
    --namespace "${NAMESPACE}" \
    --create-namespace \
    oci://ghcr.io/actions/actions-runner-controller-charts/gha-runner-scale-set-controller \
    --set image.repository=cgr.dev/chainguard/gha-runner-scale-set-controller \
    --set image.tag=latest

⚠️ Please ensure that the arc-gha-rs-controller pod is running in the arc-system namespace before proceeding to the next step.

2. To configure the runner scale set, you can follow the official documentation here.

For that, you will need two things:

• A GitHub repository with a workflow that uses runner scale sets
• A runner registration token which we refer GITHUB_PAT

INSTALLATION_NAME="arc-runner-set"
NAMESPACE="arc-runners"
GITHUB_CONFIG_URL="https://github.com/<org/repo/enterprise>" # make sure to replace this with your GitHub repository URL or GitHub Enterprise URL
GITHUB_PAT="<PAT>" # make sure to replace this with your GitHub PAT

helm install "${INSTALLATION_NAME}" \
    --namespace "${NAMESPACE}" \
    --create-namespace \
    --set githubConfigUrl="${GITHUB_CONFIG_URL}" \
    --set githubConfigSecret.github_token="${GITHUB_PAT}" \
    oci://ghcr.io/actions/actions-runner-controller-charts/gha-runner-scale-set

⚠️ Please ensure that the arc-runner-set pod is running in the arc-runners namespace before proceeding to the next step.

⚠️ The GITHUB_PAT is not the only way to authenticate with GitHub. You can use other methods like GitHub App. You can check the values.yaml file for more information: https://github.com/actions/actions-runner-controller/blob/master/charts/gha-runner-scale-set/values.yaml

Once you did that you can create and run a workflow that uses runner scale sets like the following:

🤖 You can see the self-hosted runner that you registered within the project's runners tab. To get more detail about using self-hosted runners in workflow, here is the official documentation you can refer to.

name: Actions Runner Controller Demo
on:
  workflow_dispatch:

jobs:
  Explore-GitHub-Actions:
    # You need to use the INSTALLATION_NAME from the previous step
    runs-on: arc-runner-set
    steps:
    - run: echo "🎉 This job uses runner scale set runners!"

That's it! You have successfully tested the gha-runner-scale-set-controller image.

What are Chainguard Containers?

Chainguard Containers are minimal container images that are secure by default.

In many cases, the Chainguard Containers tagged as :latest contain only an open-source application and its runtime dependencies. These minimal container images typically do not contain a shell or package manager. Chainguard Containers are built with Wolfi, our Linux undistro designed to produce container images that meet the requirements of a more secure software supply chain.

The main features of Chainguard Containers include:

• Minimal design, without unnecessary software bloat
• Daily builds to ensure container images are up-to-date with available security patches
• High quality build-time SBOMs attesting to the provenance of all artifacts within the image
• Verifiable signatures provided by Sigstore
• Reproducible builds with Cosign and apko (read more about reproducibility)

For cases where you need container images with shells and package managers to build or debug, most Chainguard Containers come paired with a -dev variant.

Although the -dev container image variants have similar security features as their more minimal versions, they feature additional software that is typically not necessary in production environments. We recommend using multi-stage builds to leverage the -dev variants, copying application artifacts into a final minimal container that offers a reduced attack surface that won’t allow package installations or logins.

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Trademarks

This software listing is packaged by Chainguard. The trademarks set forth in this offering are owned by their respective companies, and use of them does not imply any affiliation, sponsorship, or endorsement by such companies.