Multi-stage Builds

Using multiple FROM statements in a single Dockerfile to optimize image size.

Edit Concept ✏️

Multi-stage Builds

Multi-stage builds allow you to use multiple FROM statements in your Dockerfile. Each FROM instruction begins a new stage of the build. You can selectively copy artifacts from one stage to another, leaving behind everything you don’t want in the final image.

Key Benefits

  • Smaller Images: By excluding build-time dependencies (compilers, SDKs, build tools) from the final runtime image, you significantly reduce the attack surface and download size.
  • Simplified CI/CD: You don’t need to maintain separate Dockerfiles for building and running. Everything is contained in one file.
  • Layer Optimization: Only the final stage’s layers are included in the final image.

How It Works

You name your stages using AS name and then use COPY --from=name to pull specific files into the next stage.

# Build Stage
FROM node:20 AS build
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build

# Runtime Stage
FROM nginx:alpine
COPY --from=build /app/dist /usr/share/nginx/html