name: NestJS Deployment description: Docker builds, Memory tuning, and Graceful shutdown. metadata: labels: [nestjs, deployment, docker, k8s] triggers: files: ['Dockerfile', 'k8s/', 'helm/'] keywords: [Dockerfile, max-old-space-size, shutdown hooks]

Deployment & Ops Standards

Priority: P1 (OPERATIONAL)

Docker optimization and production deployment standards for NestJS applications.

Docker Optimization

• Multi-Stage Builds: Mandatory.
  1. Build Stage: Install devDependencies, build NestJS (nest build).
  2. Run Stage: Copy only dist and node_modules (pruned), use node:alpine.
• Security: Do not run as root.
  • Dockerfile: USER node.

Runtime Tuning (Node.js)

• Memory Config: Container memory != Node memory.
  • Rule: Explicitly set Max Old Space.
  • Command: node --max-old-space-size=XXX dist/main
  • Calculation: Set to ~75-80% of Kubernetes Limit. (Limit: 1GB -> OldSpace: 800MB).
• Graceful Shutdown:
  • Signal: Listen to SIGTERM.
  • NestJS: app.enableShutdownHooks() is mandatory.
  • Sleep: Add a "Pre-Stop" sleep in K8s (5-10s) to allow Load Balancer to drain connections before Node process stops accepting traffic.

Init Patterns

• Database Migrations:
  • Anti-Pattern: Running migration in main.ts on startup.
  • Pro Pattern: Use an Init Container in Kubernetes that runs npm run typeorm:migration:run before the app container starts.