allow defining ipFamilyPolicy for external service

Author: nadiamoe

mailu/templates/front/service-external.yaml

@@ -19,6 +19,9 @@ spec:
 {{- with .Values.front.externalService }}
   type: {{ .type | default "ClusterIP" }}
   externalTrafficPolicy: {{ .externalTrafficPolicy | default "Local" }}
+  {{- with .ipFamilyPolicy }}
+  ipFamilyPolicy: {{ . | quote }}
+  {{- end }}
   {{- if .loadBalancerIP }}
   loadBalancerIP: {{ .loadBalancerIP }}
   {{- end }}

mailu/values.yaml

@@ -677,6 +677,7 @@ front:
   ## @param front.externalService.enabled Expose front mail ports via external service (ClusterIP or LoadBalancer)
   ## @param front.externalService.type Service type (ClusterIP or LoadBalancer)
   ## @param front.externalService.externalTrafficPolicy Service externalTrafficPolicy (Cluster or Local)
+  ## @param front.externalService.ipFamilyPolicy Service ipFamilyPolicy, for dual stack clusters.
   ## @param front.externalService.loadBalancerIP Service loadBalancerIP
   ## @param front.externalService.annotations Service annotations
   ## @param front.externalService.ports.pop3 Expose POP3 port - 110/tcp
@@ -694,6 +695,7 @@ front:
     ## type: LoadBalancer
     loadBalancerIP: ""
     externalTrafficPolicy: Local
+    # ipFamilyPolicy: SingleStack # duse PreferDualStack or RequireDualStack for dual stack clusters.
     annotations: {}
     ports:
       pop3: false