How to Secure a Self-Hosted CI/CD Runner on a VPS Without Turning It Into a Backdoor (opens in new tab)

A self-hosted CI/CD runner on a VPS should be treated like part of your production delivery chain, not just a build machine. Before using it, harden the server, disable risky SSH access, limit inbound traffic, isolate runners by trust level, keep secrets out of the VPS, avoid giving Docker jobs excessive privileges, monitor disk/CPU/memory, plan Docker cleanup, and document recovery steps. The core rule is simple: never let untrusted code run on a runner that can access production secrets or ...