[DevOps] Docker Multi-Stage Production Build Optimization & Security Hardening

[blurbeast]

Overview & Background

Production Docker containers for FlowFi backend and frontend must be lightweight, fast to build, and hardened against container breakout vulnerabilities.

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Technical Specification & Architecture

1. Backend Dockerfile Optimization (backend/Dockerfile):
   • Multi-stage build (Builder -> Production Runner).
   • Use minimal node:20-alpine base image.
   • Execute under non-root node user (USER node).
   • Reduce image size from $> 800\text{MB}$ to $< 150\text{MB}$.
2. Frontend Dockerfile Optimization (frontend/Dockerfile):
   • Next.js standalone output build (output: 'standalone' in next.config.ts).
   • Image size reduction to $< 120\text{MB}$.
3. Health Check Probes:
   • Add native Docker healthcheck instructions calling /health.

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Target Files

• backend/Dockerfile
• frontend/Dockerfile
• docker-compose.yml

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Acceptance Criteria

• Docker container images build cleanly with $< 150\text{MB}$ final size.
• Containers run as non-root user.
• Healthcheck probes report healthy status in container orchestrators.

[egwujiohaifesinachiperpetual-max]

Please assign
ETA is 4 hours