Deployment Strategies: Scenario-Based Questions

Both blue-green and canary deployments reduce risk when releasing software by controlling exposure. They differ in how traffic is managed and how gradual the rollout is.

🔵 Blue-Green Deployments

• Maintain two production environments: blue (current) and green (new).
• Deploy new version to green, test it, then switch all traffic from blue to green.
• If issues arise, roll back by redirecting traffic back to blue.

✅ Pros:

• Simple and fast rollback.
• Isolated environments — zero-downtime switch.

🚫 Cons:

• Resource-intensive — duplicate environments.
• Harder to validate under real user load before switching.

🐤 Canary Deployments

• Deploy the new version to a small subset of users (e.g., 1%, 10%).
• Gradually increase traffic over time based on metrics and error rates.
• Automated rollback possible if issues detected early.

✅ Pros:

• Real-time validation with real user traffic.
• Minimizes blast radius if something breaks.

🚫 Cons:

• Complex rollout logic and monitoring.
• Requires detailed observability and progressive routing support.

🧠 When to Use Which?

• Blue-Green: When downtime is unacceptable, and infrastructure duplication is acceptable (e.g., enterprise apps, monolith upgrades).
• Canary: When you want fine-grained control over impact, especially in high-traffic or multi-region setups (e.g., SaaS, APIs).

📌 Final Insight

Both strategies aim for safe, reliable releases. Choose based on your architecture, monitoring maturity, and ability to manage progressive traffic routing and rollback logic.