Compat changes

[sonnysideup]

Helm Chart

• relaxes kubeVersion constraint to allow deployment to v1.15 clusters
• supports admissionregistration.k8s.io/v1beta1 API version so that mutating and validating webhook configurations can be used in v1.15 clusters

Code Changes

• Generates CRDs in both v1 and v1beta1 formats
• CRD apply/delete logic branches based on retrieved K8s version (i.e. if version is >= 1.1.6, use V1 API, else use V1Beta1)

[codecov]

Codecov Report

Merging #24 (65654a7) into main (22e657e) will decrease coverage by 3.10%.
The diff coverage is 28.73%.

@@            Coverage Diff             @@
##             main      #24      +/-   ##
==========================================
- Coverage   79.75%   76.64%   -3.11%     
==========================================
  Files          24       25       +1     
  Lines        1531     1593      +62     
==========================================
  Hits         1221     1221              
- Misses        223      280      +57     
- Partials       87       92       +5     

Impacted Files	Coverage Δ
pkg/crd/v1beta1.go	0.00% <0.00%> (ø)
pkg/crd/crd.go	53.52% <78.12%> (+8.20%)	⬆️
controllers/sparkcluster_controller.go	42.66% <0.00%> (-4.89%)	⬇️
controllers/raycluster_controller.go	44.34% <0.00%> (+0.90%)	⬆️

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[sonnysideup]

@steved @ddl-audi

I tested this against two local clusters, v1.15.12 and v 1.16.15, and the chart/code switching works as expected. My expectation is that we'll remove support for v1.15 in the near future and, of course, I'm happy to help push this forward in any way possible.

Re: code changes, the k8s.io/apiextensions-apiserver pkg defines separate interfaces/clients/types for the different versions. This makes it difficult to create reusable functions that leverage a single interface. 😞 Instead, I create a separate set of duplicate, "v1beta1" functions and tried to limit my modifications to the existing code paths (because of my formerly-stated expectation). It's not DRY, I can't look at myself in the mirror right now, but this works.