apiVersion: "logging.openshift.io/v1"
kind: "ClusterLogging"
metadata:
  name: "instance"
spec:
  managementState: "Managed"
  logStore:
    type: "elasticsearch"
    retentionPolicy: 
      application:
        maxAge: 6h
      infra:
        maxAge: 3h
      audit:
        maxAge: 1d
    elasticsearch:
      nodeCount: 4
      redundancyPolicy: "SingleRedundancy"
      resources:
        requests:
          memory: "2Gi"
      storage:
        storageClassName: "gp2"
        size: "20Gi"
  visualization:
    type: "kibana"
    kibana:
      resources: {}
      replicas: 1
  collection:
    logs:
      type: "fluentd"
      fluentd: {}
$ oc get pod -n openshift-operators-redhat
NAME                                      READY   STATUS             RESTARTS        AGE
elasticsearch-operator-5fff5b7d9d-t4c48   1/2     CrashLoopBackOff   5 (2m15s ago)   7m57s

EO log:
{"_ts":"2022-01-10T08:20:35.831827261Z","_level":"0","_component":"elasticsearch-operator","_message":"Failed to update Elasticsearch status. Trying again...","cluster":"elasticsearch","error":{"ErrStatus":{"metadata":{},"status":"Failure","message":"Elasticsearch.logging.openshift.io \"elasticsearch\" is invalid: spec.indexManagement.policies.phases.delete.pruneNamespacesInterval: Invalid value: \"\": spec.indexManagement.policies.phases.delete.pruneNamespacesInterval in body should match '^([0-9]+)([yMwdhHms]{0,1})$'","reason":"Invalid","details":{"name":"elasticsearch","group":"logging.openshift.io","kind":"Elasticsearch","causes":[{"reason":"FieldValueInvalid","message":"Invalid value: \"\": spec.indexManagement.policies.phases.delete.pruneNamespacesInterval in body should match '^([0-9]+)([yMwdhHms]{0,1})$'","field":"spec.indexManagement.policies.phases.delete.pruneNamespacesInterval"}]},"code":422}},"namespace":"openshift-logging"}
{"_ts":"2022-01-10T08:20:35.832021207Z","_level":"0","_component":"elasticsearch-operator","_message":"Could not update CR for Elasticsearch","_error":{"msg":"Elasticsearch.logging.openshift.io \"elasticsearch\" is invalid: spec.indexManagement.policies.phases.delete.pruneNamespacesInterval: Invalid value: \"\": spec.indexManagement.policies.phases.delete.pruneNamespacesInterval in body should match '^([0-9]+)([yMwdhHms]{0,1})$'"},"cluster":"elasticsearch","namespace":"openshift-logging","retries":0}
{"_ts":"2022-01-10T08:20:35.838778293Z","_level":"0","_component":"elasticsearch-operator","_message":"Failed to update Elasticsearch status. Trying again...","cluster":"elasticsearch","error":{"ErrStatus":{"metadata":{},"status":"Failure","message":"Elasticsearch.logging.openshift.io \"elasticsearch\" is invalid: spec.indexManagement.policies.phases.delete.pruneNamespacesInterval: Invalid value: \"\": spec.indexManagement.policies.phases.delete.pruneNamespacesInterval in body should match '^([0-9]+)([yMwdhHms]{0,1})$'","reason":"Invalid","details":{"name":"elasticsearch","group":"logging.openshift.io","kind":"Elasticsearch","causes":[{"reason":"FieldValueInvalid","message":"Invalid value: \"\": spec.indexManagement.policies.phases.delete.pruneNamespacesInterval in body should match '^([0-9]+)([yMwdhHms]{0,1})$'","field":"spec.indexManagement.policies.phases.delete.pruneNamespacesInterval"}]},"code":422}},"namespace":"openshift-logging"}
{"_ts":"2022-01-10T08:20:35.838833599Z","_level":"0","_component":"elasticsearch-operator","_message":"Could not update CR for Elasticsearch","_error":{"msg":"Elasticsearch.logging.openshift.io \"elasticsearch\" is invalid: spec.indexManagement.policies.phases.delete.pruneNamespacesInterval: Invalid value: \"\": spec.indexManagement.policies.phases.delete.pruneNamespacesInterval in body should match '^([0-9]+)([yMwdhHms]{0,1})$'"},"cluster":"elasticsearch","namespace":"openshift-logging","retries":0}
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x1666462]


goroutine 401 [running]:
github.com/openshift/elasticsearch-operator/internal/elasticsearch.(*ElasticsearchRequest).populateNodes(0xc001d68640, 0x0, 0x0)
	/go/src/github.com/openshift/elasticsearch-operator/internal/elasticsearch/cluster.go:312 +0x142
github.com/openshift/elasticsearch-operator/internal/elasticsearch.(*ElasticsearchRequest).CreateOrUpdateElasticsearchCluster(0xc001d68640, 0x0, 0x0)
	/go/src/github.com/openshift/elasticsearch-operator/internal/elasticsearch/cluster.go:58 +0x1ef
github.com/openshift/elasticsearch-operator/internal/elasticsearch.Reconcile(0xc005ade000, 0x1c7d160, 0xc00007eb40, 0xc000799c20, 0x11)
	/go/src/github.com/openshift/elasticsearch-operator/internal/elasticsearch/reconciler.go:184 +0x7b7
github.com/openshift/elasticsearch-operator/controllers/logging.(*ElasticsearchReconciler).Reconcile(0xc0004aad50, 0x1c692d8, 0xc00263d380, 0xc000799c20, 0x11, 0xc000133770, 0xd, 0xc00263d380, 0xc000032000, 0x18b9680, ...)
	/go/src/github.com/openshift/elasticsearch-operator/controllers/logging/elasticsearch_controller.go:85 +0x205
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler(0xc00033d720, 0x1c69230, 0xc0006d6000, 0x1879020, 0xc000338040)
	/go/src/github.com/openshift/elasticsearch-operator/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:298 +0x30d
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem(0xc00033d720, 0x1c69230, 0xc0006d6000, 0xc00052ff00)
	/go/src/github.com/openshift/elasticsearch-operator/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:253 +0x205
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2(0xc0001337b0, 0xc00033d720, 0x1c69230, 0xc0006d6000)
	/go/src/github.com/openshift/elasticsearch-operator/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:214 +0x6b
created by sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2
	/go/src/github.com/openshift/elasticsearch-operator/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:210 +0x425