---
name: deployment-patterns
description: CI/CD pipeline patterns, Docker containerization, health checks, blue-green deployment, canary releases, rollback strategies. Use when setting up deployment pipelines, containerizing apps, or planning release strategies.
---

# Deployment Patterns

Based on ECC deployment-patterns skill.

## CI/CD Pipeline Structure

```
lint → test → build → security-scan → staging-deploy → e2e-test → prod-deploy
```

### Essential Steps
1. **Lint**: Code style, static analysis
2. **Test**: Unit + integration tests
3. **Build**: Docker image, compile
4. **Security**: Dependency scan, SAST
5. **Staging**: Deploy to staging environment
6. **E2E**: Run end-to-end tests on staging
7. **Production**: Deploy to production (with rollback plan)

## Health Checks

### Liveness Probe (Am I alive?)
```yaml
livenessProbe:
  httpGet:
    path: /healthz
    port: 8080
  initialDelaySeconds: 3
  periodSeconds: 10
```

### Readiness Probe (Am I ready to serve?)
```yaml
readinessProbe:
  httpGet:
    path: /ready
    port: 8080
  initialDelaySeconds: 5
  periodSeconds: 10
```

## Deployment Strategies

### Blue-Green (Zero Downtime)
1. Run current version on "blue"
2. Deploy new version to "green"
3. Test green thoroughly
4. Switch DNS/load-balancer to green
5. Keep blue for rollback

### Canary (Gradual Rollout)
1. Deploy to small % of users (5%)
2. Monitor error rates, latency
3. If OK → increase to 25%, then 50%, then 100%
4. If problems → rollback immediately

### Rolling (Default for Kubernetes)
- Replace pods one by one
- Built-in to Kubernetes
- Can have mixed versions briefly

## Docker Patterns

### Multi-Stage Build
```dockerfile
FROM node:20-alpine AS builder
COPY . .
RUN npm ci --production=false
RUN npm run build

FROM node:20-alpine AS runtime
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/package.json ./
RUN npm ci --only=production
EXPOSE 3000
CMD ["node", "dist/main.js"]
```

### Docker Compose

```yaml
services:
  app:
    build: .
    ports: ["3000:3000"]
    depends_on: [db, redis]
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:3000/healthz"]
  db:
    image: postgres:16
    volumes: [pgdata:/var/lib/postgresql/data]
    environment:
      POSTGRES_PASSWORD: ${DB_PASSWORD}
```

## Rollback Strategy

### Pre-deployment checklist
- [ ] Health checks configured
- [ ] Logs being captured
- [ ] Metrics dashboards ready
- [ ] Rollback procedure documented
- [ ] Last known good version tagged

### Quick rollback commands
```bash
# Kubernetes
kubectl rollout undo deployment/app

# Docker Compose
docker compose down && docker compose up -d --no-build  # use previous image

# Nginx
ln -sfn /var/www/blue /var/www/current && nginx -s reload
```

## Environment Configuration

- Use environment variables for all config
- No hardcoded secrets, URLs, ports
- Separate configs: dev, staging, production
- Use .env files for local, vault/K8s secrets for production

## Checklist

- [ ] CI pipeline covers lint → test → build → scan → deploy
- [ ] Health checks (liveness + readiness) defined
- [ ] Deployment strategy chosen (blue-green, canary, rolling)
- [ ] Rollback procedure tested
- [ ] Environment variables managed securely
- [ ] Docker image is multi-stage (small final image)
- [ ] Logs structured (JSON format with correlation IDs)