⚡ Docker Performance Optimization

# Instead of
FROM node:20          # ~1GB
 
# Use
FROM node:20-alpine   # ~150MB

# Build stage
FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build
 
# Production stage
FROM node:20-alpine AS runner
WORKDIR /app
ENV NODE_ENV=production
 
# Only copy what's needed
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
 
EXPOSE 3000
CMD ["node", "dist/server.js"]

# Bad - cache invalidation on any change
COPY . .
RUN npm install
 
# Good - leverage cache
COPY package*.json ./
RUN npm ci
COPY . .

node_modules
.git
.github
*.md
.env*
.vscode
coverage
tests
__tests__

# Enable BuildKit
export DOCKER_BUILDKIT=1
 
# Or in Docker daemon config
{
  "features": {
    "buildkit": true
  }
}

# Cache npm packages
RUN --mount=type=cache,target=/root/.npm \
    npm ci --only=production

# docker-compose.yml
services:
  frontend:
    build:
      context: ./frontend
      cache_from:
        - myapp/frontend:cache
 
  backend:
    build:
      context: ./backend
      cache_from:
        - myapp/backend:cache

# Build in parallel
docker compose build --parallel

# docker-compose.yml
services:
  app:
    image: myapp
    deploy:
      resources:
        limits:
          cpus: "2"
          memory: 512M
        reservations:
          cpus: "0.5"
          memory: 256M

HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
    CMD curl -f http://localhost:3000/health || exit 1

services:
  app:
    image: myapp
    logging:
      driver: "json-file"
      options:
        max-size: "10m"
        max-file: "3"

# Run as non-root user
RUN addgroup -g 1001 -S appgroup && \
    adduser -u 1001 -S appuser -G appgroup
 
USER appuser
 
# Use specific versions
FROM node:20.10.0-alpine3.18
 
# Scan for vulnerabilities
# docker scout cve myapp:latest

# Check image size
docker images myapp
 
# Analyze layers
docker history myapp
 
# Inspect image
docker inspect myapp
 
# Prune unused images
docker image prune -a
 
# Build with cache
docker build --cache-from myapp:latest -t myapp:new .