Deployment Strategies: Scenario-Based Questions

A blue/green deployment is a release strategy that reduces downtime and risk by running two identical environments: one active (blue) and one idle (green). You switch traffic to the green environment once the new version is validated.

🎯 Key Concepts

• Blue: Current production environment.
• Green: New environment with the updated code or configuration.
• Switch: DNS, load balancer, or gateway updates to route traffic to green.

⚙️ How It Works

1. Deploy the new version to the green environment (not serving users yet).
2. Run smoke tests, integration tests, and QA on green.
3. Switch traffic from blue to green (instant or gradual).
4. Monitor performance, errors, and rollback if needed by reverting to blue.

✅ Benefits

• Zero-downtime releases.
• Fast rollback by flipping traffic back.
• Safe testing of new features in production-like environments.

🚫 Limitations

• Requires double the infrastructure temporarily.
• Database migrations must be backward-compatible.
• Can be complex in microservices or stateful applications.

📦 When to Use

• Critical systems requiring zero-downtime (e.g., payments, APIs).
• Releases with significant risk or complex changes.
• Highly regulated industries where rollback certainty is key.

🧰 Tools & Techniques

• Spinnaker / Argo Rollouts: Kubernetes-native blue/green and canary tools.
• Terraform + ALB: Automate target group switching.
• Cloud-native: AWS CodeDeploy, Azure Pipelines, Google Cloud Deploy.

📌 Real-World Insight

Blue/green deployments reduce release anxiety. Organizations that automate testing and routing benefit from faster iterations with lower risk — critical for modern DevOps and SRE cultures.