Docker running test with nodejs and volume - node.js

Question

I'm learning docker and I'm having some troubles with the volume in a development environment with Nodejs.
I having the following simple dockerfile that aims to start my unit tests from a NodeJS parent image:
FROM node:4-onbuild
VOLUME ["/usr/src/app"]
CMD [ "npm", "test" ]
I'm running my container this way:
docker run -v /C/Users/myUser/dockertest:/usr/src/app notest
But I keep receiving the following error:
npm info it worked if it ends with ok
npm info using npm#2.15.9
npm info using node#v4.5.0
npm ERR! Linux 4.4.15-moby
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "test"
npm ERR! node v4.5.0
npm ERR! npm v2.15.9
npm ERR! path /usr/src/app/package.json
npm ERR! code ENOENT
npm ERR! errno -2
npm ERR! syscall open
npm ERR! enoent ENOENT: no such file or directory, open '/usr/src/app/package.json'
npm ERR! enoent This is most likely not a problem with npm itself
npm ERR! enoent and is related to npm not being able to find a file.
npm ERR! enoent
npm ERR! Please include the following file with any support request:
npm ERR! /usr/src/app/npm-debug.log
I don't understand why I'm not able to find the package.json file inside of the /usr/src/app folder inside of my container.
The fact is that if I'm using the following docker file :
FROM node:4-onbuild
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
CMD [ "npm", "test" ]
My tests will be running in the container, but only after building step (so I have to build each time I make a modification...) . I need to play these tests any time I want, by launching a docker command (restart ? exec ?) quickly
Thanks for your help

Answer 1

You want to COPY everything build relevant and link your codebase on containerstart.
FROM node:4.4
# Enviroment variables
ENV HOMEDIR /data
RUN mkdir -p ${HOMEDIR}
WORKDIR ${HOMEDIR}
# install all dependencies
COPY package.json ./
RUN npm install
# add node content initially
COPY . .
CMD ["npm", "test"]
And then link it on start:
version: '2'
services:
myApp:
build:
context: .
dockerfile: Dockerfile
image: "myApp"
volumes:
- .:/data
You should now be able to change your codebase without restarting/rebuilding your container.