Deployment & Ops Standards
Priority: P1 (OPERATIONAL)
Workflow: Containerize NestJS App
- Write multi-stage Dockerfile — Build stage installs devDeps and runs
nest build; run stage copies onlydistand prunednode_modules. - Set non-root user — Add
USER nodeto Dockerfile. - Tune memory — Set
--max-old-space-sizeto ~75% of container memory limit. - Enable shutdown hooks — Call
app.enableShutdownHooks()inmain.ts. - Add K8s pre-stop — Configure 5-10s sleep pre-stop hook for LB draining.
Dockerfile Example
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()mandatory. - Sleep: Add "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.tson startup. - Pro Pattern: Use Init Container in Kubernetes that runs
npm run typeorm:migration:runbefore app container starts.
Environment Variables & CI/CD
- CI/CD Pipelines (GitHub, GitLab, Azure, etc.):
- If you modify
src/config/env.validation.tsto add new environment variable, you MUST map it explicitly in your deployment pipeline/infrastructure-as-code. - Platform Context:
- Cloud Run/ECS: Variables must explicitly passed in service definition.
- Kubernetes: New variables must added to
Deploymentmanifest orConfigMap/Secret. - Lambda/Serverless: Must added to
serverless.ymlor provider console. - Fundamental Rule: Application code configuration changes "breaking changes" for infrastructure layer. Never assume environment inheritance.
Anti-Patterns
- No migrations in main.ts: Use K8s Init Containers or pre-deploy CI steps for migration runs.
- No root user in Docker: Always add
USER nodeto Dockerfile; running as root security risk. - No unbounded Node heap: Set
--max-old-space-sizeto ~75% of container memory limit.