Canary Test
ELI5 — The Vibe Check
A Canary Test is when you send a small percentage of real traffic to your new version and monitor closely to see if it behaves correctly. Unlike a smoke test (fake test requests), canary tests use real user traffic as the test. If metrics look good after the canary, you roll out to everyone.
Real Talk
Canary testing is a production testing technique where a new version receives a small fraction of real traffic (1-5%) while the system monitors error rates, latency, and business metrics. It provides confidence in a new deployment using real-world conditions before full rollout.
When You'll Hear This
"The canary test showed 3x higher error rates — hold the rollout." / "We always canary test for 30 minutes before rolling out to all traffic."
Related Terms
Blue-Green Deployment
Blue-green deployment means running two identical production environments — Blue (current) and Green (new).
Canary Release
A canary release is like sending a canary into a coal mine — you deploy the new version to a tiny fraction of users first and watch closely.
Feature Flag
A feature flag is a toggle that lets you turn features on or off without deploying new code.
Rolling Update
A Rolling Update is when you update your app one server at a time instead of all at once.
Smoke Test
A smoke test is the most basic sanity check: does the app even start? Does it not immediately crash?