Multi-stage Docker builds for smaller production images

Shipping Only What Production Needs

Development tools — compilers, build systems, test runners — should never be in a production image. Multi-stage builds let you compile in one image and copy only the output into a minimal final image.

Example: Node.js with a Build Step

# Stage 1: Build
FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build        # Produces /app/dist

# Stage 2: Production
FROM node:20-alpine
WORKDIR /app
COPY package*.json ./
RUN npm ci --omit=dev
COPY --from=builder /app/dist ./dist
CMD ["node", "dist/server.js"]

The final image contains no TypeScript compiler, no devDependencies, no source files — only the compiled output and production dependencies.

Example: Go Binary

FROM golang:1.22 AS builder
WORKDIR /src
COPY . .
RUN go build -o /bin/api ./cmd/api

FROM scratch
COPY --from=builder /bin/api /api
CMD ["/api"]

scratch is an empty image — zero OS. The Go binary is fully self-contained. This produces images under 10MB versus 800MB+ with the Go SDK. Check final image size with docker images myapp.