Glossary

Canary Deployment

Canary deployment is a strategy for gradually rolling out a new version: initially only a small percentage of traffic reaches the new version (1% → 5% → 10% → 100%). If metrics look good, the rollout continues. On problems — roll back without wide impact.

Layout

Load Balancer
  ├── v1 (95%) ── stable version
  └── v2 (5%)  ── new "canary" version

Benefits

Real users test the new version on production traffic
Problems are detected at 1% of traffic, not all of it
Smooth cutover with no downtime

Vs Blue-Green

Blue-Green: traffic switches instantly (0% or 100%)
Canary: gradually (1% → ... → 100%)

Implementation

Nginx upstream weights, Kubernetes traffic splitting, AWS CodeDeploy Canary, Istio.