harden-runner/docs/how-it-works.md

How Harden-Runner Works?

GitHub-Hosted Runners

For GitHub-hosted runners, Harden-Runner GitHub Action downloads and installs the StepSecurity Agent.

• The code to monitor file, process, and network activity is in the Agent.
• The agent is written in Go and is open source at https://github.com/step-security/agent
• The agent's build is reproducible. You can view the steps to reproduce the build here

Self-Hosted Actions Runner Controller (ARC) Runners

• ARC Harden Runner daemonset uses eBPF
• You can find more details in this blog post: https://www.stepsecurity.io/blog/introducing-harden-runner-for-kubernetes-based-self-hosted-actions-runners
• ARC Harden Runner is NOT open source.

Self-Hosted VM Runners (e.g. on EC2)

• For self-hosted VMs, you add the Harden-Runner agent into your runner image (e.g. AMI).
• Agent for self-hosted VMs is NOT open source.