node.js - docker-compose volume on node_modules but is empty

Question

I'm pretty new with Docker and i wanted to map the node_modules folder on my computer (for debugging purpose).

This is my docker-compose.yml

web:
  build: .
  ports:
    - "3000:3000"
  links:
    - db
  environment:
    PORT: 3000
  volumes:
    - .:/usr/src/app
    - /usr/src/app/node_modules
db:
  image: mongo:3.3
  ports:
    - "27017:27017"
  command: "--smallfiles --logpath=/dev/null"

I'm with Docker for Mac. When i run docker-compose up -d all go right, but it create a node_modules folder on my computer but it's empty. I go into the bash of my container and ls node_modules, all the packages was there.

How can i get the content on the container on my computer too?

Thank you

Answer 1

TL;DR Working example, clone and try: https://github.com/xbx/base-server

---

You need a node_modules in your computer (outside image) for debugging purposes first (before run the container).

If you want debug only node_modules:

volumes:
    - /path/to/node_modules:/usr/src/app/node_modules

If you want debug both your code and the node_modules:

volumes:
    - .:/usr/src/app/

Remember that you will need run npm install at least one time outside the container (or copy the node_modules directory that the docker build generates). Let me now if you need more details.

---

Edit. So, without the need of npm in OSX, you can:

1. docker build and then docker cp <container-id>:/path/to/node-modules ./local-node-modules/. Then in your docker-compose.yml mount those files and troubleshot whatever you want.
2. Or, docker build and there (Dockerfile) do the npm install in another directory. Then in your command (CMD or docker-compose command) do the copy (cp) to the right directory, but this directory is mounted empty from your computer (a volume in the docker-compose.yml) and then troubleshot whatever you want.

---

Edit 2. (Option 2) Working example, clone and try: https://github.com/xbx/base-server I did it all automatically in this repo forked from the yours.

Dockerfile

FROM node:6.3

# Install app dependencies
RUN mkdir /build-dir
WORKDIR /build-dir
COPY package.json /build-dir
RUN npm install -g babel babel-runtime babel-register mocha nodemon
RUN npm install

# Create app directory
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
RUN ln -s /build-dir/node_modules node_modules

# Bundle app source
COPY . /usr/src/app

EXPOSE 1234
CMD [ "npm", "start" ]

docker-compose.yml

web:
  build: .
  ports:
    - "1234:1234"
  links:
    - db # liaison avec la DB
  environment:
    PORT: 1234
  command: /command.sh
  volumes:
    - ./src/:/usr/src/app/src/
    - ./node_modules:/usr/src/app/node_modules
    - ./command.sh:/command.sh
db:
  image: mongo:3.3
  ports:
    - "27017:27017"
  command: "--smallfiles --logpath=/dev/null"

command.sh

#!/bin/bash

cp -r /build-dir/node_modules/ /usr/src/app/

exec npm start

Please, clone my repo and do docker-compose up. It does what you want. PS: It can be improved to do the same in a better way (ie best practices, etc)

I'm in OSX and it works for me.