add podName selection functions

[nicmorales9]

Description

This is just a followup to #1941 which used an unsatisfying way to get podNames from processGroupIDs.

I am not sure that this is much better, but they do seem like useful functions in the transition away from selecting by processGroupID.

It will be much easier to see the changes if you view by commit to avoid looking at the second commit, which changes test pod names to include processClass in the name, which is an expectation of built-in functions (GetPodName will index-out-of-bounds).

Type of change

• Code Cleanup

Discussion

I wonder if there should be some explicit creation function which does not allow FDB pods to have invalid names, as I suspect that it is not only GetPodName which could have undefined behavior if expectations aren't met.

Testing

Please describe the tests that you ran to verify your changes. Unit tests?
Manual testing?
Unit tests, manual test of restart.

Do we need to perform additional testing once this is merged, or perform in a larger testing environment?

Documentation

Docstrings have been added

Follow-up

Are there any follow-up issues that we should pursue in the future?
Arguably this could be progress towards not allowing useProcessGroupID and working more with podNames when possible, but we had trouble finding that issue before. Perhaps we should raise one?

Does this introduce new defaults that we should re-evaluate in the future?
No

[foundationdb-ci]

Result of fdb-kubernetes-operator-pr on Linux CentOS 7

• Commit ID: b4a879e
• Duration 1:48:21
• Result: ❌ FAILED
• Error: Error while executing command: if $fail_test; then exit 1; fi. Reason: exit status 1
• Build Log terminal output (available for 30 days)
• Build Workspace zip file of the working directory (available for 30 days)

[foundationdb-ci]

Result of fdb-kubernetes-operator-pr on Linux CentOS 7

• Commit ID: ba82c9c
• Duration 1:43:12
• Result: ✅ SUCCEEDED
• Error: N/A
• Build Log terminal output (available for 30 days)
• Build Workspace zip file of the working directory (available for 30 days)

[johscheuer]

LGTM 👍 Thanks!