Smaller, Faster Images With Docker Multi-Stage Builds

A naive Dockerfile bakes your compilers, dev dependencies, and source into the final image — often 1GB+. Multi-stage builds let you compile in one stage and copy only the artifacts into a slim runtime stage.

A Multi-Stage Node Dockerfile

# --- Build stage ---
FROM node:20 AS build
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

# --- Runtime stage (slim) ---
FROM node:20-slim
WORKDIR /app
COPY --from=build /app/dist ./dist
COPY --from=build /app/node_modules ./node_modules
CMD ["node", "dist/server.js"]

Why It's Smaller and Safer

• Build tools and dev dependencies never reach production.
• A smaller image means faster pulls, faster deploys, and a smaller attack surface.
• Use -slim or -alpine base images and a .dockerignore to shrink further.