improve Dockerfile (resulting in much smaller Image)

[vordenken]

Hi @clusterzx ,

this PR has changes regarding the Dockerfile.

These changes result in a much smaller image (645MB instead of 1.37GB).
It also uses npm ci instead of npm install, which is recommended in CI builds.

I tested the build locally and it worked for me, but maybe a bit more testing would be good.

EDIT: I see that the NODE_ENV is defined in ecosystem.config.js already, so adding it to the Dockerfile would be redundant - could you explain what's the reason to use pm2?

[clusterzx]

Sorry for the late reply, PM2 is used to determine termination signals and restart the application. So when a setting is changed or install is done, a SIGTERM is sent and PM2 restarts the application so the app can reload the changed .env vars.

[Daniel15]

Are python3, make, and g++ needed at runtime, or only at build time? If they're just build time dependencies, you could make the image even smaller by building in one, then copying the build artifacts to a new one that excludes all the dependencies only needed at build time. https://docs.docker.com/build/building/multi-stage/

[vordenken]

Yes, a multi-stage-build would probably be even better/smaller. After this PR I started working on a version, but had a few issues and my time is limited atm.