What is a canary release and how does it reduce deployment risk?

A canary release gradually shifts production traffic from the old version to the new version over time — for example, 1% → 5% → 25% → 50% → 100% — while continuously monitoring error rates, latency, and business metrics at each step. If any metric degrades beyond a threshold, the canary is automatically or manually aborted and all traffic returns to the old version. Only a small percentage of users experience any potential issues, limiting blast radius dramatically. The name comes from "canary in a coal mine" — a small signal of danger before it affects everyone. Tools: Kubernetes with Istio or Argo Rollouts can implement weighted traffic splitting at the service mesh level; feature flag platforms like LaunchDarkly can control canary releases at the application logic level. Canary releases are the deployment strategy of choice for high-traffic services where even brief outages affect millions of users.