Blue-Green vs Canary vs Rolling Deployment
Blue-Green deployment, Canary deployment, and Rolling deployment are three release strategies to ship new software versions with minimal downtime and controlled risk.
When to Use
Blue-Green is ideal for major updates needing instant rollback. Canary is best for testing risky features on a small subset of users. Rolling fits routine updates, swapping servers gradually.
Example
If you’re updating a shopping app, you could run a blue-green deployment (new environment, then switch traffic), a canary rollout (release to 5% of shoppers first), or a rolling update (replace servers one by one).
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Why Is It Important
These strategies let teams deliver updates with confidence, reducing downtime and customer impact.
Interview Tips
In interviews, clearly define each approach, highlight when you’d use it, and show you understand rollback and monitoring considerations.
Trade-offs
- Blue-Green: fast rollback, but requires duplicate infrastructure.
- Canary: limits risk, but needs monitoring and slower rollout.
- Rolling: cost-effective, but bugs surface slower.
Pitfalls
Skipping monitoring in canary releases, mismatched blue-green environments, or version conflicts in rolling updates are common mistakes.
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