name: docker-expert
description: Expert in Docker, docker-compose, Dockerfile patterns, and container orchestration for NestJS and Next.js applications. Use this skill when users need Docker setup, containerization, or docker-compose configuration.

Docker Expert

Overview

This skill enables AI assistants to help with Docker containerization, docker-compose setups, and container orchestration for micro startup infrastructure.

When to Use This Skill

This skill activates when users need:

• Dockerfile creation for NestJS/Next.js
• docker-compose configuration
• Container networking and volumes
• Multi-stage builds optimization
• Health checks and restart policies
• MongoDB/Redis container setup

Dockerfile Best Practices

NestJS Multi-Stage Build

FROM node:20-alpine AS base
WORKDIR /app

FROM base AS deps
COPY package*.json ./
RUN npm ci

FROM base AS builder
COPY --from=deps /app/node_modules ./node_modules
COPY . .
RUN npm run build

FROM base AS runner
ENV NODE_ENV=production
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
EXPOSE 3001
CMD ["node", "dist/main.js"]

Next.js Dockerfile

FROM node:20-alpine AS base
WORKDIR /app

FROM base AS deps
COPY package*.json ./
RUN npm ci

FROM base AS builder
COPY --from=deps /app/node_modules ./node_modules
COPY . .
RUN npm run build

FROM base AS runner
ENV NODE_ENV=production
COPY --from=builder /app/.next ./.next
COPY --from=builder /app/public ./public
COPY --from=builder /app/node_modules ./node_modules
COPY --from=builder /app/package.json ./package.json
EXPOSE 3000
CMD ["npm", "start"]

Docker Compose Patterns

Development Setup

• Use volumes for live reload
• Mount source code
• Set restart: unless-stopped
• Configure networks

Production Setup

• Use named volumes for persistence
• Set restart policies
• Configure health checks
• Use secrets management

MongoDB with Docker Compose

services:
  mongodb:
    image: mongo:7.0
    container_name: mongodb
    restart: unless-stopped
    ports:
      - "27017:27017"
    environment:
      MONGO_INITDB_ROOT_USERNAME: ${MONGO_ROOT_USERNAME}
      MONGO_INITDB_ROOT_PASSWORD: ${MONGO_ROOT_PASSWORD}
    volumes:
      - mongodb_data:/data/db
    networks:
      - app-network
    command: mongod --auth

Health Checks

healthcheck:
  test: ["CMD", "curl", "-f", "http://localhost:3001/health"]
  interval: 30s
  timeout: 10s
  retries: 3
  start_period: 40s

Best Practices

• Use multi-stage builds to reduce image size
• Leverage layer caching
• Use .dockerignore
• Set appropriate restart policies
• Use health checks for containers
• Mount volumes for persistent data
• Use networks for service isolation