blue-green-deployment-strategy

name	blue-green-deployment-strategy
description	To release new software versions with zero downtime and instant rollback capability by maintaining two identical environments (Blue and Green). Use when: Mission-critical applications where downtime is unacceptable; Complex updates that might need immediate reversion.

Purpose

To release new software versions with zero downtime and instant rollback capability by maintaining two identical environments (Blue and Green).

When to Use

• Mission-critical applications where downtime is unacceptable.
• Complex updates that might need immediate reversion.

Procedure

1. Current State: "Blue" is live (v1), serving all traffic.
2. Deploy: Deploy "Green" (v2) alongside Blue. Green is idle or internal-only.
3. Test: Run smoke tests against the Green environment.
4. Switch Traffic: Update the Load Balancer / Router to point to Green.
5. Monitor: Watch for errors.
   • Success: Terminate Blue (or keep as backup).
   • Failure: Switch Load Balancer back to Blue immediately.

Constraints

• Database schema changes must be backward compatible (Blue and Green share the DB during transition).
• Sessions might be lost if not stored in a shared store (Redis).
• Requires double resource capacity during deployment.

Expected Output

A deployment process definition that allows switching versions without user interruption.