npm package.json and docker (mounting it...)

Question

I am using Docker, so this case might look weird. But I want my whole /data directory to be mounted inside my docker container when developing.

My /data folder container my package.json file, an app directory and a bunch of other stuff. The problem is that I want my node_modules folder to NOT be persistent, only the package.json file.

I have tried a couple of things, but package.json and npm is giving me a hard time here...

• Mounting the package.json file directly will break npm. npm tries to rename the file on save, which is not possible when its a mounted file.
• Mounting the parent folder (/data) will mount the node_modules folder.
• I cant find any configuration option to put node_modules in another folder outside /data, example /dist
• Putting package.json in /data/conf mounting the /data/conf as a volume instead wont work. I cant find any way to specify the package.json path in npmrc.
• Putting package.json in /data/conf and symlinking it to /data/package.json wont work. npm breaks the symlink and replaces it with a file.

Copying data back and forth to/from inside the docker container is how I am doing it now.. A little tedious.. I also want a clean solution..

Answer 1

As you have already answered, I think that might be the only solution right now.

When you are building your Docker image, do something like:

COPY data/package.json /data/
RUN mkdir /dist/node_modules && ln -s /dist/node_modules /data/node_modules && cd /data && npm install

And for other stuff (like bower, do the same thing)

COPY data/.bowerrc /data/
COPY data/bower.json /data/
RUN mkdir /dist/vendor && ln -s /dist/vendor /data/vendor && cd /data && bower install --allow-root

And COPY data/ /data at the end (so you are able to use Dockers caching and not having to do npm/docker installation when there is a change to data.

You will also need to create the symlinks you need and store them in your git-repo. They will be invalid on the outside, but will happely work on the inside of your container.

Using this solution, you are able to mount your $PWD/data:/data without getting the npm/bower "junk" outside your container. And you will still be able to build your image as a standalone deployment of your service..

Answer 2

A similar and alternative way is to use NODE_ENV variable instead of creating a symlink.

RUN mkdir -p /dist/node_modules RUN cp -r node_modules/* /dist/node_modules/ ENV NODE_PATH /dist/node_modules

Here you first create a new directory for node_modules, copy all modules there, and have Node read the modules from there.