Devops

DevOps Essentials

Quick Reference

Assets (ready to copy):

• assets/Dockerfile.node — Multi-stage Node.js Dockerfile
• assets/Dockerfile.python — Multi-stage Python Dockerfile
• assets/github-actions.yaml — Complete CI/CD pipeline template

Decision Trees

Deployment Strategy

Where to deploy?
├─ Single app, simple → Fly.io, Railway, Render
├─ Multiple services → VPS + Docker Compose
├─ Scale needed → Kubernetes (managed: GKE, EKS)
└─ Edge/Serverless → Vercel, Cloudflare Workers

Container Strategy

What to containerize?
├─ Development → Docker Compose (all services)
├─ Production single app → Multi-stage Dockerfile
├─ Production multiple → Compose or K8s
└─ Local tools → Dev containers

Docker

Multi-stage Dockerfile (Node)

# Build stage
FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

# Production stage
FROM node:20-alpine AS runner
WORKDIR /app
ENV NODE_ENV=production
RUN addgroup -g 1001 -S nodejs && adduser -S nodejs -u 1001
COPY --from=builder --chown=nodejs:nodejs /app/dist ./dist
COPY --from=builder --chown=nodejs:nodejs /app/node_modules ./node_modules
COPY --from=builder --chown=nodejs:nodejs /app/package.json ./
USER nodejs
EXPOSE 3000
CMD ["node", "dist/main.js"]

Multi-stage Dockerfile (Python)

FROM python:3.12-slim AS builder
WORKDIR /app
RUN pip install uv
COPY pyproject.toml uv.lock ./
RUN uv sync --frozen --no-dev
COPY . .

FROM python:3.12-slim AS runner
WORKDIR /app
COPY --from=builder /app/.venv /app/.venv
COPY --from=builder /app/src ./src
ENV PATH="/app/.venv/bin:$PATH"
EXPOSE 8000
CMD ["python", "-m", "uvicorn", "src.main:app", "--host", "0.0.0.0"]

Multi-stage Dockerfile (Rust)

FROM rust:1.75-alpine AS builder
RUN apk add --no-cache musl-dev
WORKDIR /app
COPY Cargo.toml Cargo.lock ./
COPY src ./src
RUN cargo build --release

FROM alpine:3.19 AS runner
RUN adduser -D appuser
COPY --from=builder /app/target/release/myapp /usr/local/bin/
USER appuser
EXPOSE 3000
CMD ["myapp"]

Docker Compose

# docker-compose.yml
services:
  api:
    build: .
    ports:
      - "3000:3000"
    environment:
      - DATABASE_URL=postgres://user:pass@db:5432/app
    depends_on:
      db:
        condition: service_healthy

  db:
    image: postgres:16-alpine
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: pass
      POSTGRES_DB: app
    volumes:
      - postgres_data:/var/lib/postgresql/data
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U user -d app"]
      interval: 5s
      timeout: 5s
      retries: 5

  redis:
    image: redis:7-alpine
    volumes:
      - redis_data:/data

volumes:
  postgres_data:
  redis_data:

GitHub Actions

Basic CI Pipeline

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

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

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-node@v4
        with:
          node-version: 20
          cache: 'pnpm'

      - run: pnpm install
      - run: pnpm lint
      - run: pnpm test
      - run: pnpm build

With Database

jobs:
  test:
    runs-on: ubuntu-latest
    services:
      postgres:
        image: postgres:16
        env:
          POSTGRES_USER: test
          POSTGRES_PASSWORD: test
          POSTGRES_DB: test
        ports:
          - 5432:5432
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5

    env:
      DATABASE_URL: postgres://test:test@localhost:5432/test

    steps:
      - uses: actions/checkout@v4
      - run: pnpm install
      - run: pnpm db:migrate
      - run: pnpm test

Deploy to Fly.io

# .github/workflows/deploy.yml
name: Deploy

on:
  push:
    branches: [main]

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: superfly/flyctl-actions/setup-flyctl@master

      - run: flyctl deploy --remote-only
        env:
          FLY_API_TOKEN: ${{ secrets.FLY_API_TOKEN }}

Docker Build & Push

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - uses: docker/build-push-action@v5
        with:
          context: .
          push: true
          tags: ghcr.io/${{ github.repository }}:${{ github.sha }}

Quick Reference

Docker Commands

# Build
docker build -t myapp .
docker build -t myapp:v1 --target builder .

# Run
docker run -p 3000:3000 myapp
docker run -d --name myapp -p 3000:3000 myapp
docker run --rm -it myapp sh

# Compose
docker compose up -d
docker compose down
docker compose logs -f api
docker compose exec api sh

# Cleanup
docker system prune -af
docker volume prune -f

Fly.io Commands

fly launch              # Initialize
fly deploy              # Deploy
fly logs                # View logs
fly ssh console         # SSH into container
fly secrets set KEY=val # Set env vars
fly scale count 2       # Scale instances

Anti-patterns