validate parameters volgroup with vgpattern in StorageClass

[mittachaitu]

Describe the problem/challenge you have
If the user specifies both volgroup & vgpattern in StorageClass parameters
currently, volgroup will take more precedence and in end, LVM volume will be
created on user-specified volgroup. This behavior is good if volgroup value
is sub-pattern of vgpattern but if both volgroup and vgpattern differs then
CSI driver should error out about discrepancy instead of silently accepting the changes.

Note: Since volgroup is a subpattern of vgpattern good to have only vgpattern support.

Describe the solution you'd like
[A clear and concise description of what you want to happen.]

• Add validation during CreateVolume request if both volgroup and
  vgpattern are specified and if they are not matching then the driver
  should error out.

Note: This validation will also handle backward compatibility issues.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]
No

Environment:

• LVM Driver version
• Kubernetes version (use kubectl version):
• Kubernetes installer & version:
• Cloud provider or hardware configuration:
• OS (e.g. from /etc/os-release):

[abhilashshetty04]

@mittachaitu , We will add this as enhancements in our roadmap item. However, I dont see where user will provide vgpattern and volgroup together.
As i see vgpattern * wildcard as suffix in the arg. Using which schedular should return subset of matching vg hosting nodes.
However, volgroup is more definate selection process. Provisioner should return lvmnodes hosting vg which is exact match to the volgroup value.

[dsharma-dc]

@abhilashshetty04 Do we really want to handle this?

[avishnu]

Scoped for OpenEBS v4.2