deployment-pipeline-design

# Deployment Pipeline Design

Architecture patterns for multi-stage CI/CD pipelines with approval gates and deployment strategies.

## Purpose

Design robust, secure deployment pipelines that balance speed with safety through proper stage organization and approval workflows.

## When to Use

- Design CI/CD architecture
- Implement deployment gates
- Configure multi-environment pipelines
- Establish deployment best practices
- Implement progressive delivery

## Pipeline Stages

### Standard Pipeline Flow

```
┌─────────┐   ┌──────┐   ┌─────────┐   ┌────────┐   ┌──────────┐
│  Build  │ → │ Test │ → │ Staging │ → │ Approve│ → │Production│
└─────────┘   └──────┘   └─────────┘   └────────┘   └──────────┘
```

### Detailed Stage Breakdown

1. **Source** - Code checkout
2. **Build** - Compile, package, containerize
3. **Test** - Unit, integration, security scans
4. **Staging Deploy** - Deploy to staging environment
5. **Integration Tests** - E2E, smoke tests
6. **Approval Gate** - Manual approval required
7. **Production Deploy** - Canary, blue-green, rolling
8. **Verification** - Health checks, monitoring
9. **Rollback** - Automated rollback on failure

## Approval Gate Patterns

### Pattern 1: Manual Approval

```yaml
# GitHub Actions
production-deploy:
  needs: staging-deploy
  environment:
    name: production
    url: https://app.example.com
  runs-on: ubuntu-latest
  steps:
    - name: Deploy to production
      run: |
        # Deployment commands
```

### Pattern 2: Time-Based Approval

```yaml
# GitLab CI
deploy:production:
  stage: deploy
  script:
    - deploy.sh production
  environment:
    name: production
  when: delayed
  start_in: 30 minutes
  only:
    - main
```

### Pattern 3: Multi-Approver

```yaml
# Azure Pipelines
stages:
- stage: Production
  dependsOn: Staging
  jobs:
  - deployment: Deploy
    environment:
      name: production
      resourceType: Kubernetes
    strategy:
      runOnce:
        preDeploy:
          steps:
          - task: ManualValidation@0
            inputs:
              notifyUsers: 'team-leads@example.com'
              instructions: 'Review staging metrics before approving'
```

**Reference:** See `assets/approval-gate-template.yml`

## Deployment Strategies

### 1. Rolling Deployment

```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 10
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 2
      maxUnavailable: 1
```

**Characteristics:**
- Gradual rollout
- Zero downtime
- Easy rollback
- Best for most applications

### 2. Blue-Green Deployment

```yaml
# Blue (current)
kubectl apply -f blue-deployment.yaml
kubectl label service my-app version=blue

# Green (new)
kubectl apply -f green-deployment.yaml
# Test green environment
kubectl label service my-app version=green

# Rollback if needed
kubectl label service my-app version=blue
```

**Characteristics:**
- Instant switchover
- Easy rollback
- Doubles infrastructure cost temporarily
- Good for high-risk deployments

### 3. Canary Deployment

```yaml
apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: my-app
spec:
  replicas: 10
  strategy:
    canary:
      steps:
      - setWeight: 10
      - pause: {duration: 5m}
      - setWeight: 25
      - pause: {duration: 5m}
      - setWeight: 50
      - pause: {duration: 5m}
      - setWeight: 100
```

**Characteristics:**
- Gradual traffic shift
- Risk mitigation
- Real user testing
- Requires service mesh or similar

### 4. Feature Flags

```python
from flagsmith import Flagsmith

flagsmith = Flagsmith(environment_key="API_KEY")

if flagsmith.has_feature("new_checkout_flow"):
    # New code path
    process_checkout_v2()
else:
    # Existing code path
    process_checkout_v1()
```

**Characteristics:**
- Deploy without releasing
- A/B testing
- Instant rollback
- Granular control

## Pipeline Orchestration

### Multi-Stage Pipeline Example

```yaml
name: Production Pipeline

on:
  push:
    branches: [ main ]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Build application
        run: make build
      - name: Build Docker image
        run: docker build -t myapp:${{ github.sha }} .
      - name: Push to registry
        run: docker push myapp:${{ github.sha }}

  test:
    needs: build
    runs-on: ubuntu-latest
    steps:
      - name: Unit tests
        run: make test
      - name: Security scan
        run: trivy image myapp:${{ github.sha }}

  deploy-staging:
    needs: test
    runs-on: ubuntu-latest
    environment:
      name: staging
    steps:
      - name: Deploy to staging
        run: kubectl apply -f k8s/staging/

  integration-test:
    needs: deploy-staging
    runs-on: ubuntu-latest
    steps:
      - name: Run E2E tests
        run: npm run test:e2e

  deploy-production:
    needs: integration-test
    runs-on: ubuntu-latest
    environment:
      name: production
    steps:
      - name: Canary deployment
        run: |
          kubectl apply -f k8s/production/
          kubectl argo rollouts promote my-app

  verify:
    needs: deploy-production
    runs-on: ubuntu-latest
    steps:
      - name: Health check
        run: curl -f https://app.example.com/health
      - name: Notify team
        run: |
          curl -X POST ${{ secrets.SLACK_WEBHOOK }} \
            -d '{"text":"Production deployment successful!"}'
```

## Pipeline Best Practices

1. **Fail fast** - Run quick tests first
2. **Parallel execution** - Run independent jobs concurrently
3. **Caching** - Cache dependencies between runs
4. **Artifact management** - Store build artifacts
5. **Environment parity** - Keep environments consistent
6. **Secrets management** - Use secret stores (Vault, etc.)
7. **Deployment windows** - Schedule deployments appropriately
8. **Monitoring integration** - Track deployment metrics
9. **Rollback automation** - Auto-rollback on failures
10. **Documentation** - Document pipeline stages

## Rollback Strategies

### Automated Rollback

```yaml
deploy-and-verify:
  steps:
    - name: Deploy new version
      run: kubectl apply -f k8s/

    - name: Wait for rollout
      run: kubectl rollout status deployment/my-app

    - name: Health check
      id: health
      run: |
        for i in {1..10}; do
          if curl -sf https://app.example.com/health; then
            exit 0
          fi
          sleep 10
        done
        exit 1

    - name: Rollback on failure
      if: failure()
      run: kubectl rollout undo deployment/my-app
```

### Manual Rollback

```bash
# List revision history
kubectl rollout history deployment/my-app

# Rollback to previous version
kubectl rollout undo deployment/my-app

# Rollback to specific revision
kubectl rollout undo deployment/my-app --to-revision=3
```

## Monitoring and Metrics

### Key Pipeline Metrics

- **Deployment Frequency** - How often deployments occur
- **Lead Time** - Time from commit to production
- **Change Failure Rate** - Percentage of failed deployments
- **Mean Time to Recovery (MTTR)** - Time to recover from failure
- **Pipeline Success Rate** - Percentage of successful runs
- **Average Pipeline Duration** - Time to complete pipeline

### Integration with Monitoring

```yaml
- name: Post-deployment verification
  run: |
    # Wait for metrics stabilization
    sleep 60

    # Check error rate
    ERROR_RATE=$(curl -s "$PROMETHEUS_URL/api/v1/query?query=rate(http_errors_total[5m])" | jq '.data.result[0].value[1]')

    if (( $(echo "$ERROR_RATE > 0.01" | bc -l) )); then
      echo "Error rate too high: $ERROR_RATE"
      exit 1
    fi
```

## Reference Files

- `references/pipeline-orchestration.md` - Complex pipeline patterns
- `assets/approval-gate-template.yml` - Approval workflow templates

## Related Skills

- `github-actions-templates` - For GitHub Actions implementation
- `gitlab-ci-patterns` - For GitLab CI implementation
- `secrets-management` - For secrets handling