Add support for pvcs to apiserver

[psschwei]

Why are these changes needed?

Users may wish to add PVC volumes to Ray pods instead of hostPath volumes as its recommended to avoid hostPath volumes when possible due to security risks. Plus, it was something already marked to be implemented.

Related issue number

#1087

Checks

• [ X ] I've made sure the tests are passing.
• Testing Strategy
  • [ X ] Unit tests
  • Manual tests
  • This PR is not tested :(

[psschwei]

cc @Jeffwan

[blublinsky]

Hi @psschwei I am not sure I fully understand how this is supposed to work. Are you assuming that PVC is created and then passed to the cluster creation? I do not think this will work. I was assuming a different scenario, where a PVC is created for each pod during pod creation. Do we need to discuss and finalize the requirements?

[psschwei]

My goal for this PR was really just to implement this missing functionality to be able to use PVCs in the buildVols() function. Agree with you on the final scenario (PVC for each pod during creation), consider this the first step down the road towards it.

[kevin85421]

cc @blublinsky would you mind reviewing this PR? Thanks!

[kevin85421]

Hi @psschwei, would you mind resolving the conflict?

[blublinsky]

The implementation looks good. The question still remains of how to properly use it. It requires RWM volumes, because the same volume is mounted to multiple pods. The PR can benefit from additional documentation on how to use it and maybe an example

[psschwei]

Test failures don't appear to be related to my updates

Will work on pulling together an example and some documentation

[kevin85421]

Sorry about that. The CI issue should be fixed by #1145. Would you mind rebasing with the master branch? However, I found the nightly compatibility to be quite unstable. There may have been some recent breaking changes in the Ray master branch. Thanks!

[kevin85421]

cc @scarlet25151 @Jeffwan would you mind reviewing this PR? Thanks!

[scarlet25151]

the config is straight forward and LGTM. Please look into the lint issue in test file and then we may merge it.

[kevin85421]

I have not reviewed this PR, but two reviewers approve it.

[Jeffwan]

sorry for late. This change looks good to me.