[prometheus] pdb template values

[mentlak0]

What this PR does / why we need it

Which issue this PR fixes

(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged)

• fixes:
• FIX to PDB template. Here we are seeing maxUnavailable defaulting to 1. If we try to only spec minAvailable, maxUnavailable is templating due to default value. K8s does not allow both of these specs.
• This PR sees a change to allow specific values without issue.

Special notes for your reviewer

Checklist

• DCO signed
• Chart Version bumped
• Title of the PR starts with chart name (e.g. [prometheus-couchdb-exporter])

[mentlak0]

@gianrubio @naseemkullah @Xtigyro @zanhsieh @zeritti

Hello,

Would appreciate a review on this. Our prom instance keeps jumping nodes and I want to add a correct PDB

[zeritti]

@gianrubio @naseemkullah @Xtigyro @zanhsieh @zeritti

Hello,

Would appreciate a review on this. Our prom instance keeps jumping nodes and I want to add a correct PDB

Please, sign your commits so that DCO check can pass.

[mentlak0]

@zeritti Apologies, first time doing a sign off. This has now been done.

[zeritti]

We can make PDB a bit friendlier to users who would like to set minAvailable since they have to set two fields: unset default maxUnavailable and then set minAvailable. I would suggest a change in this respect - commenting the current default out in the values file and rewriting the template while setting the current default. unhealthyPodEvictionPolicyshould not be discarded.

  {{- if not (or (hasKey $pdbSpec "minAvailable") (hasKey $pdbSpec "maxUnavailable")) }}
  maxUnavailable: 1
  {{- end }}
  {{- if hasKey $pdbSpec "minAvailable" }}
  minAvailable: {{ $pdbSpec.minAvailable }}
  {{- end }}
  {{- if hasKey $pdbSpec "maxUnavailable" }}
  maxUnavailable: {{ $pdbSpec.maxUnavailable }}
  {{- end }}
  {{- if hasKey $pdbSpec "unhealthyPodEvictionPolicy" }}
  unhealthyPodEvictionPolicy: {{ $pdbSpec.unhealthyPodEvictionPolicy }}
  {{- end }}

We'd have to add a comment in the values stating that default is set to maxUnavailable=1 if neither minAvailable nor maxUnavailable is set. What dou you think?