There's a couple environment variables that the devfile spec defines:

• $PROJECTS_ROOT: A path where projects sources are mounted
• $PROJECT_SOURCE: A path to a project source, including the project root (${PROJECTS_ROOT}/<project-name>)

It's assumed that these environment variables will be set to the proper values and available in the containers defined in a devfile.

In addition to the sourceMapping field, odo currently allows the projects root to be changed by overriding the PROJECTS_ROOT environment variable in the container spec, e.g.:

components:
- name: runtime
  container:
    image: quay.io/eclipse/che-java11-maven:nightly
    memoryLimit: 768Mi
    mountSources: true
    sourceMapping: /test
    command: ['tail']
    args: [ '-f', '/dev/null']
    env:
    - name: PROJECTS_ROOT
      value: /mycustom/path/

We had some discussion last week on $PROJECT_SOURCE and decided that it wasn't valid for odo to allow it to be overridden by users, as it relies on both the value of $PROJECTS_ROOT (see redhat-developer/odo#3781 for some discussion) and where the source code is located.

So, I guess I have a couple questions:

1. Should we update the devfile spec to formally not allow $PROJECT_SOURCE to be overridden in the container spec by users?
2. Should we do the same for $PROJECTS_ROOT too? Given that the project root can still be changed by configuring sourceMapping