Splunk Operator: helm chart is not ready to be used in terraform

[yaroslav-nakonechnikov]

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Bug

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Describe the request
if you are using terraform to deploy helm chart to EKS, and using something like:

"splunkOperator.persistentVolumeClaim.storageClassName" = "gp3"

so on next deployment it will fail with:

Error: failed to replace object: PersistentVolumeClaim "splunk-operator-app-download" is invalid: spec: Forbidden: spec is immutable after creation except resources.requests and volumeAttributesClassName for bound claims

No attribute specified when one (and only one) of
  core.PersistentVolumeClaimSpec{
  	AccessModes:      {"ReadWriteOnce"},
  	Selector:         nil,
  	Resources:        {Requests: {s"storage": {i: {...}, s: "10Gi", Format: "BinarySI"}}},
- 	VolumeName:       "pvc-1d7b55ee-1939-4788-8347-bec50cedbc32",
+ 	VolumeName:       "",
  	StorageClassName: &"gp3",
  	VolumeMode:       &"Filesystem",
  	... // 3 identical fields
  }


  with helm_release.splunk-operator,
  on splunk-operator.tf line 22, in resource "helm_release" "splunk-operator":
  22: resource "helm_release" "splunk-operator" {

Expected behavior
It works without issues like this.

[yaroslav-nakonechnikov]

fixed with:

      "splunkOperator.persistentVolumeClaim.storageClassName"     = "gp3"
      "splunkOperator.volumes[0].name"                            = "app-staging"
      "splunkOperator.volumes[0].persistentVolumeClaim.claimName" = "splunk-operator-app-staging"

[yaroslav-nakonechnikov]

it is came back on 2.8.0, so reopened.

[patrykw-splunk]

Hey, I think the issue that you experience here is related to the default Kubernetes behaviour. So if PVC is created dynamically in StatefulSet via volumeClaimTemplates (which is a way how we do that currently in splunk-operator) then its spec is treated as an immutable object.
Forbidden: spec is immutable after creation except resources.requests and volumeAttributesClassName for bound claims

We have it on our roadmap to allow using externally created PVs for the statefulsets and just providing them via volumeName.
An option that is possible to use from the release 3.0.0 is #1509 feature, which enables usage of externally created PVs and bounding them to statefulset via matchLabel selector. Although I suggest you to test it thoroughly on the test environment first

[yaroslav-nakonechnikov]

@patrykw-splunk yes, i understand the reason.
but somehow other helm charts doesn't complain about specifying volumes.

ps. 2.8.1, issue still there