feat: pod disruption budget

Added a flag to enable/disable a [pod disruption budget](https://kubernetes.io/docs/tasks/run-application/configure-pdb/), helping Connaisseur to be always available.

fixes #1850

charts/connaisseur/templates/_helpers.tpl

@@ -165,6 +165,13 @@ Create the name of the redis tls secret
 {{- include "connaisseur.name" . }}-redis-tls
 {{- end -}}
 
+{{/*
+Create the name of the pod disruption budget
+*/}}
+{{- define "connaisseur.podDisruptionBudget" -}}
+{{- include "connaisseur.name" . }}-pod-disruption-budget
+{{- end -}}
+
 {{/*
 Extract Kubernetes Minor Version.
 */}}

charts/connaisseur/templates/pod_disruption_budget.yaml

@@ -0,0 +1,21 @@
+{{ if .Values.kubernetes.podDisruptionBudget -}}
+apiVersion: policy/v1
+kind: PodDisruptionBudget
+metadata:
+  name: {{ include "connaisseur.podDisruptionBudget" . }}
+  namespace: {{ .Release.Namespace }}
+  labels:
+      {{- include "connaisseur.labels" . | nindent 4 }}
+spec:
+  {{- with .Values.kubernetes.podDisruptionBudget }}
+  {{- if hasKey . "minAvailable" }}
+  minAvailable: {{ .minAvailable }}
+  {{- end }}
+  {{- if hasKey . "maxUnavailable" }}
+  maxUnavailable: {{ .maxUnavailable }}
+  {{- end }}
+  {{- end }}
+  selector:
+    matchLabels:
+      {{- include "connaisseur.selectorLabels" . | nindent 8 }}
+{{- end }}

charts/connaisseur/values.yaml

@@ -102,6 +102,10 @@ kubernetes:
   # (except for pods – see kubernetes.deployment.podLabels for that)
   additionalLabels: {}
 
+  # activate pod disruption budget
+  # can set `minAvailable` and `maxUnavailable` values
+  podDisruptionBudget: {}
+
 # -----------------------------------------------------
 
 # changes to connaisseur application logic