[kube-prometheus-stack] Add downward compatibility for Prometheus CRD…

… CRD fields

Running the latest prom-stack versions on legacy OpenShift clusters with no influence on the preinstalled CRDs results in errors such as this:

failed to create typed patch object (..): .spec.scrapeConfigNamespaceSelector: field not declared in schema

This patch provides a workaround using this values.yaml:

prometheus:
  prometheusSpec:
    scrapeConfigNamespaceSelector: null
    scrapeConfigSelectorNilUsesHelmValues: null
    scrapeConfigSelector: null
Signed-off-by: Johannes Schnatterer <johannes.schnatterer@cloudogu.com>

charts/kube-prometheus-stack/Chart.yaml

@@ -23,7 +23,7 @@ name: kube-prometheus-stack
 sources:
   - https://github.com/prometheus-community/helm-charts
   - https://github.com/prometheus-operator/kube-prometheus
-version: 62.3.0
+version: 62.4.0
 appVersion: v0.76.0
 kubeVersion: ">=1.19.0-0"
 home: https://github.com/prometheus-operator/kube-prometheus

charts/kube-prometheus-stack/templates/prometheus/prometheus.yaml

@@ -253,13 +253,13 @@ spec:
   scrapeConfigSelector:
     matchLabels:
       release: {{ $.Release.Name | quote }}
-{{ else }}
+{{ else if not (eq .Values.prometheus.prometheusSpec.scrapeConfigSelector nil) }}
   scrapeConfigSelector: {}
 {{- end }}
 {{- if .Values.prometheus.prometheusSpec.scrapeConfigNamespaceSelector }}
   scrapeConfigNamespaceSelector:
 {{ tpl (toYaml .Values.prometheus.prometheusSpec.scrapeConfigNamespaceSelector | indent 4) . }}
-{{ else }}
+{{ else if not (eq .Values.prometheus.prometheusSpec.scrapeConfigNamespaceSelector nil) }}
   scrapeConfigNamespaceSelector: {}
 {{- end }}
 {{- if .Values.prometheus.prometheusSpec.storageSpec }}