Problem Statement
What is a Canary release?
Explanation
Canary release deploys new version to small subset of users (5-10%) while majority uses old version. Monitor metrics (errors, latency, business KPIs) from canary group. If healthy, gradually increase percentage (25%, 50%, 75%, 100%). If issues detected, rollback canary traffic to old version. Named after 'canary in coal mine' - early warning system.
Process: deploy v2 to canary pool (10% traffic), monitor for 30-60 minutes, compare canary metrics vs baseline, if healthy increase to 25%, repeat until 100%, rollback if issues. Benefits: reduced blast radius (only small percentage affected), early issue detection, data-driven rollout decisions, gradual confidence building.
Requirements: monitoring and metrics, automated health checks, traffic routing capability, rollback automation. Use cases: high-risk deployments, user-facing changes, new features with uncertain impact. Understanding canary releases enables safe progressive rollouts.
