add/update how disruption budget works

templates/_helpers.tpl

@@ -34,9 +34,12 @@ Expand the name of the chart.
 {{/*
 Compute the maximum number of unavailable replicas for the PodDisruptionBudget.
 This defaults to (n/2)-1 where n is the number of members of the server cluster.
+Add a special case for replicas=1, where it should default to 0 as well.
 */}}
 {{- define "vault.pdb.maxUnavailable" -}}
-{{- if .Values.serverHA.disruptionBudget.maxUnavailable -}}
+{{- if eq (int .Values.serverHA.replicas) 1 -}}
+{{ 0 }}
+{{- else if .Values.serverHA.disruptionBudget.maxUnavailable -}}
 {{ .Values.serverHA.disruptionBudget.maxUnavailable -}}
 {{- else -}}
 {{- ceil (sub (div (int .Values.serverHA.replicas) 2) 1) -}}

templates/server-ha-statefulset.yaml

@@ -34,7 +34,10 @@ spec:
         release: {{ .Release.Name }}
         component: server
     spec:
-      #TODO: look at how Consul exposes affinity
+    {{- if .Values.server.affinity }}
+      affinity:
+        {{ tpl .Values.server.affinity . | nindent 8 | trim }}
+    {{- end }}
       terminationGracePeriodSeconds: 10
       volumes:
         - name: config

values.yaml

@@ -136,6 +136,20 @@ serverHA:
     # replicas. If you'd like a custom value, you can specify an override here.
     maxUnavailable: null
 
+  # Affinity Settings
+  # Commenting out or setting as empty the affinity variable, will allow
+  # deployment to single node services such as Minikube
+  affinity: |
+    podAntiAffinity:
+      requiredDuringSchedulingIgnoredDuringExecution:
+        - labelSelector:
+            matchLabels:
+              app: {{ template "vault.name" . }}
+              release: "{{ .Release.Name }}"
+              component: server
+          topologyKey: kubernetes.io/hostname
+
+
 # Configuration for DNS configuration within the Kubernetes cluster.
 # This creates a service that routes to all agents (client or server)
 # for serving DNS requests. This DOES NOT automatically configure kube-dns