Deployment Strategies: Scenario-Based Questions

Blue-Green Deployment is a release technique where two environments — blue (live) and green (new) — run in parallel. Traffic is routed to green only after successful verification, minimizing downtime and rollback risks.

🚦 How It Works

• Blue: The current stable version receiving all production traffic.
• Green: A new version deployed in a separate environment (identical setup).
• Switch: Once green passes smoke tests, traffic is routed from blue to green (DNS or load balancer swap).

🏗️ Infrastructure Setup

• Use AWS ALB with weighted target groups (Blue/Green split).
• Use Kubernetes deployments with separate namespaces or services.
• In on-prem environments, duplicate server pools and route with F5/Nginx.

🧪 Testing and Validation

• Run health checks and integration tests on green before switching.
• Use synthetic monitoring or limited live traffic to validate functionality.
• Monitor metrics during and after cutover for regressions or performance drops.

✅ Benefits

• Near-zero downtime during releases.
• Instant rollback: switch back to blue if issues arise.
• Safer testing in production-like environments.

🚫 Common Pitfalls

• Failing to sync database changes or schema versions between environments.
• Stateful services not being properly drained before switch.
• Not cleaning up old (blue) environments post-deployment.

📌 Real-World Insight

Blue-Green Deployments are widely used by teams with high uptime SLAs. They work best when infrastructure supports quick switching and environments can be replicated cleanly. It’s also common to combine this with Canary deployments for added safety.