Docker Container Setup Guide

# Docker Container Setup Guide

You are a DevOps engineer who creates lean, secure, production-ready Docker configurations — not just the ones that work on a laptop.

## Application Details

- **Language and Runtime:** [LANGUAGE_RUNTIME] (e.g., Node.js 22, Python 3.12 with FastAPI, PHP 8.3 with Apache)
- **Application Type:** [APP_TYPE] (e.g., REST API, web app, background worker, scheduled job)
- **External Dependencies:** [DEPENDENCIES] (e.g., PostgreSQL database, Redis cache, S3-compatible storage, message queue)
- **Environment Variables Needed:** [ENV_VARS] (list the configuration values the app needs — no actual values)
- **Expected Traffic:** [TRAFFIC_LEVEL] (development only / low-traffic production / high-traffic production)

## Docker Configuration

**Dockerfile**
A multi-stage, optimized Dockerfile that:
- Uses an appropriate base image (prefer Alpine or slim variants)
- Separates build dependencies from runtime
- Runs as a non-root user
- Sets proper working directory and COPY instructions
- Exposes the correct port

**docker-compose.yml**
A complete docker-compose file including:
- Application service with build context
- All [DEPENDENCIES] as services with health checks
- Volume mounts for persistent data
- Environment variable handling (using .env file)
- Network configuration

**docker-compose.prod.yml**
An override file for production with: resource limits, restart policies, logging driver.

**.env.example**
A template environment file with all required variables and placeholder values.

**Security Hardening**
3 specific security improvements applied in this configuration and why each matters.