GitHub-hosted runners are convenient, but for high-volume teams the bill adds up fast. Self-hosting can cut costs and improve performance, but security and isolation are concerns.
Fireactions is an open-source CI/CD runner orchestrator that uses Firecracker microVMs — the same tech behind AWS Lambda — to spin up isolated, ephemeral runners for every job.
The benefits: jobs run in clean VMs, secrets and caches don't leak between runs, and startup is measured in seconds. You also get full control over hardware, OS, and Docker daemon configuration.
Setup involves installing the Fireactions agent on a Linux host with KVM enabled, registering it with your GitHub org, and defining VM templates per workload. Most teams see CI cost reductions of 60–80% versus GitHub-hosted runners at scale.
Fireactions is a strong fit for teams running 10k+ minutes of CI per month. For smaller orgs, GitHub's hosted runners remain the easier choice.
