Make the sync directory more consistent

[johnmcollier]

Currently, odo uses the following logic for determining what folder to sync to:

1. If a single project is defined in the devfile, it syncs to /projects/<projectName>
2. If no projects are defined, or if there are multiple projects defined, it syncs to /projects
3. (Most recently) If the sourceMapping field is set, it syncs to the folder specified.

The logic for 1 and 2 were in place because we wanted to maintain compatibility with Che devfiles initially, a number of which relied on the assumption that the code for a component would be under /projects/<projectName>. However, as it turned out, there would be a number of blockers that would prevent Che devfiles from working with odo. Additionally, this was before we had implemented support for source mapping, allowing the user to configure where the source gets synced to.

The downside to this current approach is that the expected sync directory isn't consistent for somebody writing a devfile, and as they add or remove projects from the devfile, the sync directory will change, potentially breaking the commands in their devfile each time.

@elsony @maysunfaisal and I chatted last week about this, and decided that long term, it would be better if odo always synced to /projects, unless the sourceMapping field is set, in which case, it will sync to the sourceMapping folder. This will ensure the sync directory is much more consistent and not subject to unwritten rules in odo.

[kadel]

@elsony @maysunfaisal and I chatted last week about this, and decided that long term, it would be better if odo always synced to /projects, unless the sourceMapping field is set, in which case, it will sync to the sourceMapping folder. This will ensure the sync directory is much more consistent and not subject to unwritten rules in odo.

+1 with one exception. If sourceMapping is not set it should check for PROJECTS_ROOT env variable and use that, and only if the PROJECTS_ROOT is not set then use /projects

This is my understanding based on how it is defined here: https://github.com/devfile/kubernetes-api/blob/80da7f73abaf7572c2bfb5c6dd1c1a696d2380b1/pkg/apis/workspaces/v1alpha1/containerComponent.go#L42-L46

[maysunfaisal]

I think we should also consider the possibility of clonePath in projects.. If we're going to eventually support this property, we should take it into consideration with this issue

https://devfile.github.io/devfile/_attachments/api-reference.html