docker-agent

Docker Agent

Production-ready Dockerfiles and compose configs. Fixes common container problems fast.

When to Use

• "Write a Dockerfile for my Python/Node/Go app"
• "My container won't start"
• "Set up docker-compose for my local dev environment"
• "My image is 2GB — help me reduce it"

Python Dockerfile (production-ready)

# Build stage — install dependencies separately for cache efficiency
FROM python:3.12-slim AS builder
WORKDIR /build

# Install build deps first (changes rarely — cached layer)
COPY requirements.txt .
RUN pip install --no-cache-dir --user -r requirements.txt

# Runtime stage — clean image without build tools
FROM python:3.12-slim AS runtime
WORKDIR /app

# Non-root user for security
RUN useradd --create-home appuser
USER appuser

# Copy installed packages from builder
COPY --from=builder /root/.local /home/appuser/.local
ENV PATH=/home/appuser/.local/bin:$PATH

# Copy app code last (changes most often — cache invalidated last)
COPY --chown=appuser:appuser . .

EXPOSE 8000
CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

Node.js Dockerfile

FROM node:20-alpine AS builder
WORKDIR /build
COPY package*.json .
RUN npm ci --only=production

FROM node:20-alpine AS runtime
WORKDIR /app
RUN adduser -D appuser
USER appuser
COPY --from=builder /build/node_modules ./node_modules
COPY --chown=appuser:appuser . .
EXPOSE 3000
CMD ["node", "server.js"]

docker-compose for Local Dev

# docker-compose.yml
services:
  api:
    build: .
    ports:
      - "8000:8000"
    environment:
      - DATABASE_URL=postgresql://postgres:password@db:5432/myapp
      - REDIS_URL=redis://redis:6379
    volumes:
      - .:/app          # hot reload in dev
    depends_on:
      db:
        condition: service_healthy
      redis:
        condition: service_started
    restart: unless-stopped

  db:
    image: postgres:16-alpine
    environment:
      POSTGRES_DB: myapp
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: password
    volumes:
      - postgres_data:/var/lib/postgresql/data
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U postgres"]
      interval: 5s
      timeout: 5s
      retries: 5

  redis:
    image: redis:7-alpine
    volumes:
      - redis_data:/data

volumes:
  postgres_data:
  redis_data: