Multi-Stage Image Builds
Multi-stage builds allow you to use multiple FROM statements in a single Dockerfile, separating the heavy build environment from the minimal runtime image.
1. Why Multi-Stage Builds Matter
Building modern React, Next.js, Go, or Java apps requires heavy SDK compilers, TypeScript tools, and devDependencies. By using multi-stage builds, you compile your code in a temporary build stage and copy only the compiled assets into a razor-thin production image!
2. Production Next.js / React Multi-Stage Dockerfile
# ========================================== # STAGE 1: Build & Compile Stage # ========================================== FROM node:18-alpine AS builder WORKDIR /app # Copy dependency locks COPY package*.json ./ RUN npm ci # Copy source code and build production bundle COPY . . RUN npm run build # ========================================== # STAGE 2: Minimal Production Runtime Stage # ========================================== FROM node:18-alpine AS runner WORKDIR /app ENV NODE_ENV=production # Copy only production dependencies & compiled output from STAGE 1! COPY --from=builder /app/package*.json ./ COPY --from=builder /app/.next ./.next COPY --from=builder /app/public ./public RUN npm ci --only=production EXPOSE 3000 CMD ["npm", "start"]
Result: Image size shrinks from 1.2 GB (with node_modules & dev compilers) down to ~85 MB!
Next Up
Learn Container Security Practices: non-root users (USER node), vulnerability scanning, and read-only filesystems.
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