블루-그린 및 점진적 배포

Shipping a new version to 100% of users at once is risky, a hidden bug hits everyone instantly.

Progressive deployment strategies reduce blast radius by exposing changes gradually and enabling fast rollback.

In a blue-green setup you run two environments:

• Blue, the current live version
• Green, the new version, fully deployed but not yet receiving traffic

You switch traffic to green when ready, and switch back instantly if something breaks.

A gradual rollout sends a small percentage of traffic to the new version first, then increases it as confidence grows.

• 5% then 25% then 50% then 100%
• Watch error rates at each step

Also called a canary release.

Cloudflare lets you upload a new Worker version without deploying it to all traffic.

Use gradual deployments to assign a percentage of requests to each version.

For custom logic you can route in code, for example send a cohort to the new behavior based on a hash of the user ID.

During a rollout, monitor:

• Error rate / 5xx responses
• Latency (p50, p95, p99)
• CPU time
• Business KPIs

Compare the new version against the baseline before increasing traffic.

The key benefit of progressive deploys is fast rollback, shift traffic back to the known-good version immediately.

Tie rollout steps to CI checks. If error rates exceed a threshold, the pipeline automatically reverts to the previous version.

During blue-green, both versions may run at once, so schema changes must be backward compatible.

• Add columns before removing old ones
• Use expand-then-contract migrations

Deploy safely at the edge by:

• Uploading versions without full deploy
• Splitting traffic gradually and watching metrics
• Keeping rollback one command away
• Making migrations backward compatible

What is the defining characteristic of a canary (gradual) rollout?

You learned safe deployment strategies:

• Blue-green keeps a hot standby for instant switching
• Gradual rollouts shift traffic in steps while you watch metrics
• Versioned uploads and percentage splits make this easy on Cloudflare
• Backward-compatible migrations keep both versions healthy

Progressive delivery turns scary deploys into routine, reversible events.