Canary Deployment
// Definition
Routing a small slice of traffic (1%, 5%) to a new version while the rest stays on the old one. Metrics from the canary decide whether to progress or roll back. Limits blast radius and surfaces issues that staging missed.
// Related terms
Blue-Green Deployment
Running two identical production environments, one live (blue) and one idle (green). Deploy to green, smoke-test, then switch traffic. Rollback is instant — flip the switch back.
Feature Flag
A runtime toggle that turns code paths on or off without redeploying. Enables progressive rollouts, A/B tests, and instant kill switches. Decouples deploy from release — code ships dark and is enabled later.
Rollback
Reverting a deployment to the previous known-good version when a release introduces a regression. Modern pipelines aim for one-command rollback; database migrations are the usual complication.
Learn more · CI/CD for QA Engineers
Chapter 6 · Lesson 4: Review and Stretch Goals