Che: Add volumes to machine configuration

[gazarenkov]

Since in Che6 we move to multicontainer/sidecar way it become more important to be able to describe "interesting for workspace" persistence storage as a part of workspace configuration.

Currently, there are two ways to describe in a case of attaching (mounting, syncing etc) volumes (folders) with persisted data:

• /projects folder attached to "ws-agent" machine is a sign to attach identified persistence storage to it
• everything else (like an arbitrary PVC) described in an infrastructure specific recipe (docker volume mount, PVC etc).

It is proposed to add "volumes" section into workspace->environment->machine config, like:

 volumes:
    <name>:
        path:</path/to/machine's/folder>
        properties:{} - do we need that as option?

@garagatyi @sleshchenko @skabashnyuk

[garagatyi]

Would be useful to persist .m2 and other development data

[benoitf]

how the "path" attribute is working in the case of a PVC ?

[sleshchenko]

I think path field will be used for definition of mountPath in case of PVC https://docs.openshift.com/enterprise/3.1/dev_guide/persistent_volumes.html#claims-as-volumes-in-pods

[benoitf]

@sleshchenko the persistence volume name used to do the mount will be inside properties attributes ? because I read

"properties:{} - do we need that as option?"

[garagatyi]

properties might do mounting behavior not consistent across different infrastructure implementations. So, we should think whether we should add them

[gazarenkov]

As far as I understand, the mapping in this case can be:

volumes:
    <name>: - PVC name
        path:</path/to/machine's/folder> - mountPath

[benoitf]

@gazarenkov ok name was not documented so I was thinking it was not acting as the 'source' name

[garagatyi]

name doesn't have to be exactly PVC name, we just need an ability to match specific PVC to a volume from our model. Technical solutions can be different.

[sleshchenko]

Technical solutions can be different.

For example, we can put the corresponding label with Che Volume name into PVC metadata.

[benoitf]

And where can we specify subpath

like for example

new VolumeMountBuilder()
                .withMountPath(cheWorkspaceProjectsStorage)
                .withName(workspacesPersistentVolumeClaim)
                .withSubPath(subPath)

[benoitf]

https://docs.openshift.com/container-platform/3.4/dev_guide/volumes.html#volumes-specifying-a-subpath

[gazarenkov]

I do not think we should (and can) cover all the infrastructure features.
I think we need some policies for "known" cases (such as /projects folder) to be able:

• to identify this declaration with PVC described in the recipe and make sure workspace conf is consistent
• to apply some defaults (taking into account infra's configuration) - for ex add declared volume (infra should know how) as a PVC
  All the arbitrary PVC defined in recipe can just work (or not with clear message) as normally.

[benoitf]

I agree that we can't cover all infrastructure features, but using a specific folder from a volume looks like a basic features. (It's also a feature used in OpenShiftConnector in 5.x)

[garagatyi]

@benoitf can you elaborate on how do you see it work for both openshift and docker infrastructures for some recipe supported by both, e.g. compose (not supported now, though)