What Is an Ephemeral Runner?
An ephemeral runner is a continuous-integration worker that handles exactly one job on a freshly provisioned machine and is then thrown away. Because nothing carries over between jobs, each build starts from a known-clean state with no leftover files, processes, or secrets. This model is the foundation of secure, reproducible CI on hosted and managed runner platforms.
Why it matters
Reusing a long-lived machine lets one job poison the next through cached credentials, leftover dependencies, or a half-finished process. Ephemeral runners eliminate that whole class of flakiness and security risk by guaranteeing a clean slate every time. Managed platforms such as Latchkey provision ephemeral, autoscaled runners on demand so you get isolation without operating a fleet yourself.
Related concepts
- Self-hosted runners can be made ephemeral by re-imaging between jobs
- Just-in-time (JIT) registration tokens scope a runner to a single job
- Warm pools pre-boot ephemeral runners to cut cold-start latency