Deployment Strategies

Deployment Strategies

Purpose

Master production deployment strategies:

• Zero-downtime deployments
• Risk mitigation
• Rollback procedures
• Progressive delivery
• Infrastructure patterns

When to Use

Invoke this skill when:

• Planning production deployments
• Designing deployment pipelines
• Troubleshooting failed deploys
• Implementing new deployment strategy
• Reducing deployment risk

Deployment Strategies

1. Blue-Green Deployment

Concept: Two identical environments (Blue=current, Green=new)

┌─────────────┐
│  Load       │
│  Balancer   │
└──────┬──────┘
       │
       ├─────────────┐
       │             │
  ┌────▼───┐    ┌───▼────┐
  │ Blue   │    │ Green  │
  │ (v1.0) │    │ (v2.0) │
  │ LIVE   │    │ IDLE   │
  └────────┘    └────────┘

After testing Green:
Switch traffic → Green becomes LIVE

If issues:
Switch back → Instant rollback

Implementation:

// Example using AWS ELB
async function blueGreenDeploy(version: string): Promise<void> {
  // 1. Deploy to green environment
  await deployToEnvironment('green', version);

  // 2. Run smoke tests on green
  const testsPass = await runSmokeTests('green');
  if (!testsPass) {
    throw new Error('Green environment failed tests');
  }

  // 3. Gradually shift traffic
  await shiftTraffic('blue', 'green', {
    steps: [10, 25, 50, 100],
    intervalMinutes: 5,
  });

  // 4. Monitor for errors
  const errors = await monitorErrors('green', { duration: '10m' });
  if (errors > THRESHOLD) {
    await rollback('blue');
    throw new Error('Rollback triggered due to errors');
  }

  // 5. Decommission blue
  await decommission('blue');
}

Pros: ✅ Instant rollback, ✅ Zero downtime, ✅ Full testing before switch Cons: ❌ 2x infrastructure cost, ❌ Database migrations tricky

---

2. Canary Deployment

Concept: Gradually roll out to small percentage of users

Phase 1: 5% traffic → v2.0
         95% traffic → v1.0

Phase 2: 25% traffic → v2.0
         75% traffic → v1.0

Phase 3: 50% traffic → v2.0
         50% traffic → v1.0

Phase 4: 100% traffic → v2.0