Canary Release
Gradually rolling out changes to a small subset of users before full deployment.
Definition
A canary release is a deployment strategy that rolls out changes to a small subset of users before full deployment. Named after canaries used to detect gas in mines, canary releases expose potential issues to limited users before broader impact.
Canary deployments enable real-world testing with actual user traffic while limiting blast radius. Metrics are closely monitored, with automatic rollback if the canary performs worse than the existing version.
Why It Matters
Testing in production is the only way to catch certain issues, but affects real users. Canary releases provide production testing while limiting exposure when problems occur.
For teams releasing frequently, canary strategies are essential for sustainable velocity.
Examples in Practice
A new feature is released to 1% of users as a canary; metrics show no degradation, so rollout continues to 10%, then 100%.
Canary monitoring detects increased error rates for the new version, triggering automatic rollback before most users are affected.
A/B testing is combined with canary release, measuring both quality and feature effectiveness simultaneously.