Releasing to a fraction first
A canary release sends a small percentage of live traffic to a new version while most users stay on the stable one. If the canary behaves, you raise its share; if it misbehaves, you cut it to zero. The proxy is what makes this precise.
How splitting works
The reverse proxy or mesh defines weighted routes. A rule might say ninety percent to version one and ten percent to version two. The proxy honors these weights per request, so the split is gradual and reversible.
- Percentage based splits send a fixed slice to the canary.
- Header or user based splits target specific cohorts, like internal staff first.
- Progressive rollout raises the canary weight in steps as metrics stay healthy.
Why it reduces risk
A bad deploy hits only the canary slice, so the blast radius is small. Because the proxy controls weights centrally, rollback is instant: set the canary weight back to zero and traffic returns to the stable version without redeploying.
Key idea
Traffic splitting lets a proxy route a small weighted slice to a new version, so canaries limit blast radius and rollback is just a weight change.