DevOps & CI/CD

Overview

Practices for automating build, test, and deployment pipelines.

CI/CD Pipeline

Pipeline Stages

┌──────────┐   ┌──────────┐   ┌──────────┐   ┌──────────┐   ┌──────────┐
│  Commit  │ → │  Build   │ → │   Test   │ → │  Deploy  │ → │ Release  │
│          │   │          │   │          │   │ Staging  │   │   Prod   │
└──────────┘   └──────────┘   └──────────┘   └──────────┘   └──────────┘
     │              │              │              │              │
     │         ┌────┴────┐    ┌────┴────┐        │              │
     │         │ Compile │    │  Unit   │        │              │
     │         │  Lint   │    │  Integ  │        │              │
     │         │  Type   │    │   E2E   │        │              │
     │         └─────────┘    └─────────┘        │              │
     │                                           │              │
   Trigger                                    Manual?       Approval?

GitHub Actions

# .github/workflows/ci.yml
name: CI

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      - name: Lint
        run: npm run lint

      - name: Type check
        run: npm run type-check

      - name: Test
        run: npm run test -- --coverage

      - name: Upload coverage
        uses: codecov/codecov-action@v3

      - name: Build
        run: npm run build

      - name: Upload build artifact
        uses: actions/upload-artifact@v4
        with:
          name: build
          path: dist/

  deploy-staging:
    needs: build
    if: github.ref == 'refs/heads/main'
    runs-on: ubuntu-latest
    environment: staging

    steps:
      - name: Download build artifact
        uses: actions/download-artifact@v4
        with:
          name: build
          path: dist/

      - name: Deploy to staging
        run: |
          # Deploy script here
          echo "Deploying to staging..."

  deploy-production:
    needs: deploy-staging
    runs-on: ubuntu-latest
    environment:
      name: production
      url: https://myapp.com

    steps:
      - name: Deploy to production
        run: |
          echo "Deploying to production..."

Matrix Builds

jobs:
  test:
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        os: [ubuntu-latest, windows-latest, macos-latest]
        node: [18, 20, 22]
        exclude:
          - os: windows-latest
            node: 18

    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ matrix.node }}
      - run: npm ci
      - run: npm test

Deployment Strategies

Blue-Green Deployment

Before:
┌─────────────────────────────────────────┐
│           Load Balancer                  │
└─────────────────┬───────────────────────┘
                  │
          ┌───────┴───────┐
          ↓               ↓
    ┌───────────┐   ┌───────────┐
    │  Blue     │   │  Green    │
    │  (v1.0)   │   │  (idle)   │
    │  ACTIVE   │   │           │
    └───────────┘   └───────────┘

Deploy v1.1 to Green:
    ┌───────────┐   ┌───────────┐
    │  Blue     │   │  Green    │
    │  (v1.0)   │   │  (v1.1)   │
    │  ACTIVE   │   │  testing  │
    └───────────┘   └───────────┘

Switch traffic:
          ┌───────────────┐
          ↓               ↓
    ┌───────────┐   ┌───────────┐
    │  Blue     │   │  Green    │
    │  (v1.0)   │   │  (v1.1)   │
    │  standby  │   │  ACTIVE   │
    └───────────┘   └───────────┘

Canary Deployment

# Kubernetes canary with Argo Rollouts
apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: my-app
spec:
  replicas: 10
  strategy:
    canary:
      steps:
        - setWeight: 10        # 10% traffic to new version
        - pause: { duration: 5m }
        - setWeight: 30
        - pause: { duration: 5m }
        - setWeight: 50
        - pause: { duration: 10m }
        - setWeight: 100
      analysis:
        templates:
          - templateName: success-rate
        startingStep: 2        # Start analysis at 30%
        args:
          - name: service-name
            value: my-app

Rolling Update

# Kubernetes rolling update
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 4
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1        # Can exceed replicas by 1
      maxUnavailable: 0  # All must be available during update
  template:
    spec:
      containers:
        - name: app
          image: my-app:v1.1
          readinessProbe:
            httpGet:
              path: /health