Gradual exposure
A canary release rolls out a new version to a small fraction of traffic first, watches its health, and only widens the rollout if metrics stay good. The name comes from the canary that warned miners of danger. If the new version misbehaves, only that small slice is affected.
How it runs
- Route a small percent, say one or five percent, to the new version.
- Watch error rate, latency, and key business metrics against the old version.
- If healthy, increase the percentage in steps until it reaches all traffic.
- If unhealthy, roll back by routing everyone to the old version.
Why teams like it
- Limited blast radius because failures hit few users.
- Real signal from production traffic, not just a test environment.
- Pairs naturally with automated rollback when a metric crosses a threshold.
Key idea
A canary release exposes a new version to a small traffic slice and widens only if live metrics stay healthy.