Syncing local code inside docker container without having container service running - node.js

Question

I have created a docker image which has an executable node js app.
I have multiple modules which are independent of themselves. These modules are created as a package inside docker using npm link command hence can be required in my node js index file.
The directory structure is as
|-node_modules
|-src
|-app
|-index.js
|-independent_modules
|-some_independent_task
|-some_other_independent_task
While building the image I have created npm link for every independent module in the root node_modules. This creates a node_modules folder inside every independent module, which is not present in local. This is only created inside the container.
I require these modules in src/app/index.js and proceed with my task.
This docker image does not use a server to keep the container running, hence the container stops when the process ends.
I build the image using
docker build -t demoapp
To run the index.js in the dev environment I need to mount the local src directory to docker src directory to reflect the changes without rebuilding the image.
For mounting and running I use the command
docker run -v $(pwd)/src:/src demoapp node src/index.js
The problem here is, in local, there is no dependencies installed i.e no node_modules folder is present. Hence while mounting local directory into docker, it replaces it with an empty one, hence the dependencies installed inside docker in node_modules vanish out.
I tried using .dockerignore to not mount the node_modules folder but it didn't work. Also, keeping empty node_modules in local also doesn't work.
I also tried using docker-compose to keep volumes synced and hide out node_modules from it, but I think this only syncs when the docker is running with any server i.e docker container keeps running.
This is the docker-compose.yml I used
# docker-compose.yml
version: "2"
services:
demoapp_container:
build: .
image: demoapp
volumes:
- "./src:/src"
- "/src/independent_modules/some_independent_task/node_modules"
- "/src/independent_modules/some_other_independent_task/node_modules"
container_name: demoapp_container
command: echo 'ready'
environment:
- NODE_ENV=development
I read this here that using this it will skip the `node_modules from syncing.
But this also doen't works for me.
I need to execute this index.js every time within a stopped docker container with the local code synced to the docker workdir and skipping the dependencies folder i.e node_modules.
One more thing if it could happen will be somewhat helpful. Every time I do docker-compose up or docker-compose run it prints ready. Can I have something, where I can override the command in docker-compose with the command passed from CLI.
Something like docker-compose run | {some command}.

Answer 1

You've defined a docker-compose file but you're not actually using it.
Since you use docker run, this is the command you should try:
docker run \
-v $(pwd)/src:/src \
-v "/src/independent_modules/some_independent_task/node_modules"
-v "/src/independent_modules/some_other_independent_task/node_modules"
demoapp \
node src/index.js
If you want to use the docker-compose, you should change command to be node src/index.js. Then you can use docker-compose up instead of the whole docker run ....