Slimming Down node_modules in Docker Images
February 04, 2019 ― 1 minute
Everyone knows the meme about the size of the
node_modules folder so I'll try to make this one quick. You can (in some cases) drastically reduce the size of a resulting docker image by avoiding the inclusion of non-production node modules.
Create a builder image
This is an easy one, and probably something you're already used to doing. Create a Dockerfile as you would normally but this time we'll add an
as keyword. This essentially creates a name for the current image in the
FROM node:8-alpine as builderWORKDIR /app COPY src/ ./src COPY package* ./ COPY tsconfig.json ./ RUN npm install RUN npm run build
Install your production dependencies
We're also going to use the same
as keyword in this image to tell the final image where to get the production dependencies from.
FROM node:10-alpine as dependenciesWORKDIR /app # Copy over the original package.json, we need this to npm install! COPY --from=builder /app/package* ./ RUN npm install --production
Compose your final image
Now we can reference the previous images using the
--from argument * gasps *. This means we can compose a final image from all the previous stages without the
FROM node:10-alpine WORKDIR /app # Copy over our built application code COPY --from=builder /app/dist ./dist # Copy over the original package.json so we know how to start it COPY --from=builder /app/package.json . # Copy over our hopefully much lighter node_modules folder COPY --from=dependencies /app/node_modules ./node_modules CMD ["npm", "run", "start"]
Putting all three snippets together in a single Dockerfile should achieve a much thinner image now that we're not including all our development dependencies as well.
For more about multi-stage builds, see the official Docker documentation.