feat: Add optional PodDisruptionBudget (#272)

Adds support for creating a PodDisruptionBudget. This will configure K8s to always attempt to have either minAvailable pods running, or no more than minUnavailable pods unavailable. This will prevent an outage in the event of nodes running the pods being taken out of service for maintenance.

charts/pihole/Chart.yaml

@@ -3,7 +3,7 @@ description: Installs pihole in kubernetes
 home: https://github.com/MoJo2600/pihole-kubernetes/tree/master/charts/pihole
 name: pihole
 appVersion: "2023.05.2"
-version: 2.18.0
+version: 2.19.0
 sources:
   - https://github.com/MoJo2600/pihole-kubernetes/tree/master/charts/pihole
   - https://pi-hole.net/

charts/pihole/templates/pdb.yaml

@@ -0,0 +1,21 @@
+{{- if .Values.podDisruptionBudget.enabled -}}
+apiVersion: policy/v1
+kind: PodDisruptionBudget
+metadata:
+  name: {{ template "pihole.fullname" . }}-pdb
+  labels:
+    app: {{ template "pihole.name" . }}
+    chart: {{ template "pihole.chart" . }}
+    release: {{ .Release.Name }}
+    heritage: {{ .Release.Service }}
+spec:
+{{- if .Values.podDisruptionBudget.minAvailable }}
+  minAvailable: {{ .Values.podDisruptionBudget.minAvailable }}
+{{- end }}
+{{- if .Values.podDisruptionBudget.maxUnavailable }}
+  maxUnavailable: {{ .Values.podDisruptionBudget.maxUnavailable }}
+{{- end }}
+  selector:
+    matchLabels:
+      app: {{ template "pihole.name" . }}
+{{- end }}

charts/pihole/values.yaml

@@ -482,7 +482,8 @@ podAnnotations:
   # prometheus.io/scrape: 'true'
 
 # -- any initContainers you might want to run before starting pihole
-extraInitContainers: []
+extraInitContainers:
+  []
   # - name: copy-config
   #   image: busybox
   #   args:
@@ -524,3 +525,12 @@ podDnsConfig:
   nameservers:
     - 127.0.0.1
     - 8.8.8.8
+
+# -- configure a Pod Disruption Budget
+podDisruptionBudget:
+  # -- set to true to enable creating the PDB
+  enabled: false
+  # -- minimum number of pods Kubernetes should try to have running at all times
+  minAvailable: 1
+  # -- maximum number of pods Kubernetes will allow to be unavailable. Cannot set both `minAvailable` and `maxAvailable`
+  # maxUnavailable: 1