Clean Yarn cache from Docker image

[deboer-tim]

The Theia docker image is pretty big. When I dug into it, there's 335Mb in the Yarn cache that is pulled in during build and then never used again. I've found some other projects that have added "&& yarn clear cache" to their docker builds, which would clean this up and reduce the image size by 335Mb.

Also noticed the --production=true flag while I was investigating this, not sure if that would speed up the build or remove unnecessary dependencies too.

[hexa00]

Sounds like a good idea to do this... --production will not install devDependencies which should be OK.

[akosyakov]

It should work if we install @theia/cli as a global node module instead of a dev dependency.

It could be worth to investigate yarn autoclean for this matter as well.

[akosyakov]

RFC to avoid using yarn cache: yarnpkg/rfcs#53 - discussed how to work it around for different cases

[akosyakov]

I've tried to remove @theia/cli from dev dependencies, but it is not so straightforward:

• theia build does not work from global modules, webpack cannot be resolved for some reasons
• and we use theia start to start the app

To use --production flag these issues should be resolved first.

[akosyakov]

We've managed to reduce the size of theiaide/theia significantly by:

• using the alpine image as the base image: https://github.com/nodejs/docker-node#nodealpine
• removing electron dependencies
• get rid of build tools like python and make using the separate build stage: https://docs.docker.com/engine/userguide/eng-image/multistage-build/#use-multi-stage-builds

Docker file is here: https://github.com/theia-ide/theia-apps/blob/master/theia-docker/Dockerfile