/devops-infrastructure

name: devops-infrastructure
description: Guides Docker, CI/CD pipelines, deployment strategies, infrastructure as code, and observability setup. Use when writing Dockerfiles, configuring GitHub Actions, planning deployments, setting up monitoring, or when asked about containers, pipelines, Terraform, or production infrastructure.

DevOps & Infrastructure

When to Load

• **Trigger**: Docker, CI/CD pipelines, deployment configuration, monitoring, infrastructure as code
• **Skip**: Application logic only with no infrastructure or deployment concerns

DevOps Workflow

Copy this checklist and track progress:

DevOps Setup Progress:
- [ ] Step 1: Containerize application (Dockerfile)
- [ ] Step 2: Set up CI/CD pipeline
- [ ] Step 3: Define deployment strategy
- [ ] Step 4: Configure monitoring & alerting
- [ ] Step 5: Set up environment management
- [ ] Step 6: Document runbooks
- [ ] Step 7: Validate against anti-patterns checklist

Docker Best Practices

Multi-Stage Build

# WRONG: Single stage, bloated image
FROM node:22
WORKDIR /app
COPY . .
RUN npm install
RUN npm run build
CMD ["node", "dist/index.js"]
# Result: 1.2GB image with devDependencies and source code

# CORRECT: Multi-stage build
FROM node:22-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build
RUN npm prune --omit=dev

FROM node:22-alpine AS runner
WORKDIR /app
ENV NODE_ENV=production
RUN addgroup -g 1001 appgroup && adduser -u 1001 -G appgroup -s /bin/sh -D appuser
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
COPY --from=builder /app/package.json ./
USER appuser
EXPOSE 3000
CMD ["node", "dist/index.js"]
# Result: ~150MB image, no devDependencies, non-root user

Python Multi-Stage

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

FROM python:3.12-slim AS runner
WORKDIR /app
RUN useradd -r -s /bin/false appuser
COPY --from=builder /app/.venv /app/.venv
COPY --from=builder /app/src ./src
ENV PATH="/app/.venv/bin:$PATH"
USER appuser
CMD ["python", "-m", "src.main"]

Layer Caching

# WRONG: Cache busted on every code change
COPY . .
RUN npm ci

# CORRECT: Dependencies cached separately
COPY package*.json ./
RUN npm ci                  # cached unless package.json changes
COPY . .                    # only source code changes bust this layer

.dockerignore

node_modules
.git
.env
*.md
.vscode
coverage
dist
__pycache__
.pytest_cache
*.pyc

Security

# Always pin versions
FROM node:22-alpine   # NOT node:latest

# Don't run as root
USER appuser

# Read-only filesystem where possible
# docker run --read-only --tmpfs /tmp myapp

# Scan images
# docker scout cves myimage:latest
# trivy image myimage:latest

CI/CD Pipeline Design

GitHub Actions Structure

name: CI/CD
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 22
          cache: "npm"
      - run: npm ci
      - run: npm run lint

  test:
    runs-on: ubuntu-latest
    needs: lint
    services:
      postgres:
        image: postgres:16
        env:
          POSTGRES_DB: testdb
          POSTGRES_PASSWORD: postgres
        ports: ["5432:5432"]
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 22
          cache: "npm"
      - run: npm ci
      - run: npm test

  build:
    runs-on: ubuntu-latest
    needs: test
    permissions:
      contents: read
      packages: write
    steps:
      - uses: actions/checkout@v4
      - uses: docker/setup-buildx-action@v3
      - uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
      - id: meta
        uses: docker/metadata-action@v5
        with:
          images: ghcr.io/${{ github.repository }}
          tags: type=sha
      - uses: docker/build-push-action@v5
        with:
          push: ${{ github.event_name == 'push' }}
          tags: ${{ steps.meta.outputs.tags }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

  deploy:
    runs-on: ubuntu-latest
    needs: build
    if: github.ref == 'refs/heads/main'
    environment: production
    steps:
      - run: echo "Deploy to production"

Caching Strategies

# Node modules
- uses: actions/setup-node@v4
  with:
    cache: "npm"

# Python with uv
- name: Cache uv
  uses: actions/cache@v4
  with:
    path: ~/.cache/uv
    key: uv-${{ runner.os }}-${{ hashFiles('uv.lock') }}

# Docker layer caching
- uses: docker/build-push-action@v5
  with:
    cache-from: type=gha
    cache-to: type=gha,mode=max

Deployment Strategies

Blue-Green Deployment

1. Run two identical environments: Blue (live) and Green (idle)
2. Deploy new version to Green
3. Run smoke tests on Green
4. Switch load balancer to Green
5. Green is now live, Blue is idle
6. Rollback: switch back to Blue

Pros: Instant rollback, zero downtime
Cons: 2x infrastructure cost during deploy

Canary Deployment

1. Deploy new version to small subset (5% of traffic)
2. Monitor error rates and latency
3. Gradually increase: 5% -> 25% -> 50% -> 100%
4. Rollback: route all traffic back to old version

Pros: Limited blast radius, real-world testing
Cons: More complex routing, longer rollout

Rolling Deployment

1. Replace instances one at a time
2. Each new instance passes health checks before next starts
3. Continue un