Docker and symlinks

Question

I\'ve got a repo set up like this:

/config
   config.json
/worker-a
   Dockerfile
   
   /code
/worker-b
   Dockerfile
   

        

Answer 1

I also ran into this problem, and would like to share another method that hasn't been mentioned above. Instead of using npm link in my Dockerfile, I used yalc.

1. Install yalc in your container, e.g. RUN npm i -g yalc.
2. Build your library in Docker, and run yalc publish (add the --private flag if your shared lib is private). This will 'publish' your library locally.
3. Run yalc add my-lib in each repo that would normally use npm link before running npm install. It will create a local .yalc folder in your Docker container, create a symlink in node_modules that works inside Docker to this folder, and rewrite your package.json to refer to this folder too, so you can safely run install.
4. Optionally, if you do a two stage build, make sure that you also copy the .yalc folder to your final image.

Below an example Dockerfile, assuming you have a mono repository with three packages: models, gui and server, and the models repository must be shared and named my-models.

# You can access the container using:
#   docker run -it my-name sh
# To start it stand-alone:
#   docker run -it -p 8888:3000 my-name

FROM node:alpine AS builder
# Install yalc globally (the apk add... line is only needed if your installation requires it)
RUN apk add --no-cache --virtual .gyp python make g++ && \
  npm i -g yalc
RUN mkdir /packages && \
  mkdir /packages/models && \
  mkdir /packages/gui && \
  mkdir /packages/server
COPY ./packages/models /packages/models
WORKDIR /packages/models
RUN npm install && \
  npm run build && \
  yalc publish --private
COPY ./packages/gui /packages/gui
WORKDIR /packages/gui
RUN yalc add my-models && \
  npm install && \
  npm run build
COPY ./packages/server /packages/server
WORKDIR /packages/server
RUN yalc add my-models && \
  npm install && \
  npm run build

FROM node:alpine
RUN mkdir -p /app
COPY --from=builder /packages/server/package.json /app/package.json
COPY --from=builder /packages/server/dist /app/dist
# Make sure you copy the yalc registry too.
COPY --from=builder /packages/server/.yalc /app/.yalc
COPY --from=builder /packages/server/node_modules /app/node_modules
COPY --from=builder /packages/gui/dist /app/dist/public
WORKDIR /app
EXPOSE 3000
CMD ["node", "./dist/index.js"]

Hope that helps...