[che-dev] Simplify mounting of project sources to plugins

[Lukas Krejci <lkrejci@xxxxxxxxxx>]

Hi all,

I started working on https://github.com/eclipse/che/issues/12413 - 
introduce mountProjectSources to che-plugin.yaml (a part of 
https://github.com/eclipse/che/issues/12249 which tracks improvements to 
che-plugin.yaml and devfile).

I wanted to discuss how such attribute should actually be used.

Currently we handle the mounting of project sources to the plugin 
container by explicitly mounting a predefined volume named "projects". 
This requires the plugin author to know about existence of such volume. 
On the other hand it enables the plugin author to place the project 
sources anywhere on the plugin container's filesystem.

The suggested solution to this is to add a new boolean attribute called 
"mountProjectSources". The problem I see with that attribute is that it 
hardcodes the mount-path of the sources to `/projects`. This again 
requires the plugin author to know about the location and also doesn't 
enable them to change it.

So what about mountProjectSources becoming "projectSourcesMountPath" or 
"sourcesMountPath" specifying the path on the container filesystem where 
the plugin expects the sources to be? If the attribute has a defined 
value in che-plugin.yaml, the sources are mounted to the path. If the 
attribute is not defined in che-plugin.yaml, the sources are not mounted 
at all.

I've created a couple of comments on
https://github.com/eclipse/che/issues/12413 using which you can vote on 
the solution you prefer.

1) "mountProjectSources" as a boolean
2) "mountSources" as a boolean
3) "projectSourcesMountPath" as a string
4) "sourcesMountPath" as a string

Whichever of those 4 comments will get the most votes will determine the 
chosen solution :)

Thanks,

Lukas