[loki-distributed] Add the possibility for setting maxUnavailable parameter for PDB

[triceras]

Karpenter is unable to evict the loki pods because they have Pod Disruption Budget set. This behavior will prevent the nodes from deprovisioning. The easier way to overcome this issue is to allow the users to set a value for maxUnavailable. So if the user wants to disable the PDB for a certain loki pod he could do so by setting maxUnavailable=0.

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:white_check_mark: zanhsieh
:x: triceras
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[Aaron-ML]

@zanhsieh any reason we decided to use maxUnvailable versus just setting minAvailable defaults with conditional logic to say > 2 = minAvailable:1?

[zanhsieh]

@zanhsieh any reason we decided to use maxUnvailable versus just setting minAvailable defaults with conditional logic to say > 2 = minAvailable:1?

@Aaron-ML You are welcome to fire another PR to the value you think it reasonable.

[diranged]

I don't understand this PR - the PR replaces all of the component-level settings with a single global setting burried under .Values.distributor. Why not follow the much more standard practice of allowing operators to define their own PDB:

{{- with .Values.$component.podDisruptionBudget }}
podDisruptionBudget:
  {{ toYaml . | nindent XX }}
{{- end }}

This PR seems flawed to me.. unless I am missing something here.

[triceras]

There is no way to disable PDB if you wish to do so. There should be a way to disable PDB if the user wants to do so. PDB should be an optional setting instead of compulsory specially if using some autoscaler tool such as Karpenter.

On Tue, Sep 6, 2022 at 7:28 AM Matt Wise @.***> wrote:

I don't understand this PR - the PR replaces all of the component-level settings with a single global setting burried under .Values.distributor. Why not follow the much more standard practice of allowing operators to define their own PDB:

{{- with .Values.$component.podDisruptionBudget }}podDisruptionBudget: {{ toYaml . | nindent XX }}{{- end }}

This PR seems flawed to me.. unless I am missing something here.

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