Add topologySpreadConstraints for gateway

The default topologySpreadConstraints tries to schedule each
of the gateway replicas onto different nodes in the cluster.

This can be customised as/if required.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

Author: alexellis

chart/openfaas/Chart.yaml

@@ -2,7 +2,7 @@ apiVersion: v2
 type: application
 description: OpenFaaS - Serverless Functions Made Simple
 name: openfaas
-version: 14.2.71
+version: 14.2.72
 sources:
 - https://github.com/openfaas/faas
 - https://github.com/openfaas/faas-netes

chart/openfaas/templates/gateway-dep.yaml

@@ -30,6 +30,10 @@ spec:
       labels:
         app: gateway
     spec:
+      {{- if and .Values.gateway.topologySpreadConstraints .Values.openfaasPro }}
+      topologySpreadConstraints:
+      {{- toYaml .Values.gateway.topologySpreadConstraints | nindent 8 }}
+      {{- end }}
       {{- if .Values.operator.create }}
       serviceAccountName: {{ .Release.Name }}-operator
       {{- else }}

chart/openfaas/values.yaml

@@ -110,6 +110,15 @@ gateway:
     failureThreshold: 3
     successThreshold: 1
 
+  topologySpreadConstraints:
+    - maxSkew: 1
+      topologyKey: "kubernetes.io/hostname"
+      # Set to "DoNotSchedule" if you need a strict enforcement
+      whenUnsatisfiable: ScheduleAnyway
+      labelSelector:
+        matchLabels:
+          app: gateway
+
 eventSubscription:
   endpoint: ""
   endpointSecret: ""