Add support for additional service labels to the helm chart

Problem: It's not possible to add extra lables to the nginx gateway
service (to select a particular CiliumLoadBalancerIPPool, for example)

Solution: Add support for adding extra labels to the nginx gateway service

Testing: `helm template ngf charts/nginx-gateway-fabric/ --set service.labels.lb-ip-pool=private -s templates/service.yaml`
rendered a service manifest with an extra label `lb-ip-pool=private` as expected

Author: cyril-s

charts/nginx-gateway-fabric/README.md

@@ -300,6 +300,7 @@ The following table lists the configurable parameters of the NGINX Gateway Fabri
 | `nginxGateway.snippetsFilters.enable` | Enable SnippetsFilters feature. SnippetsFilters allow inserting NGINX configuration into the generated NGINX config for HTTPRoute and GRPCRoute resources. | bool | `false` |
 | `nodeSelector` | The nodeSelector of the NGINX Gateway Fabric pod. | object | `{}` |
 | `service.annotations` | The annotations of the NGINX Gateway Fabric service. | object | `{}` |
+| `service.labels` | The additional labels of the NGINX Gateway Fabric service. | object | `{}` |
 | `service.create` | Creates a service to expose the NGINX Gateway Fabric pods. | bool | `true` |
 | `service.externalTrafficPolicy` | The externalTrafficPolicy of the service. The value Local preserves the client source IP. | string | `"Local"` |
 | `service.loadBalancerIP` | The static IP address for the load balancer. Requires service.type set to LoadBalancer. | string | `""` |

charts/nginx-gateway-fabric/templates/service.yaml

@@ -6,6 +6,9 @@ metadata:
   namespace: {{ .Release.Namespace }}
   labels:
     {{- include "nginx-gateway.labels" . | nindent 4 }}
+    {{- with .Values.service.labels }}
+    {{- toYaml . | nindent 4 }}
+    {{- end }}
 {{- if .Values.service.annotations }}
   annotations:
 {{ toYaml .Values.service.annotations | indent 4 }}

charts/nginx-gateway-fabric/values.schema.json

@@ -604,6 +604,12 @@
           "title": "annotations",
           "type": "object"
         },
+        "labels": {
+          "description": "The additional labels of the NGINX Gateway Fabric service.",
+          "required": [],
+          "title": "labels",
+          "type": "object"
+        },
         "create": {
           "default": true,
           "description": "Creates a service to expose the NGINX Gateway Fabric pods.",

charts/nginx-gateway-fabric/values.yaml

@@ -330,6 +330,9 @@ service:
   # -- The annotations of the NGINX Gateway Fabric service.
   annotations: {}
 
+  # -- The additional labels of the NGINX Gateway Fabric service.
+  labels: {}
+
   # -- The static IP address for the load balancer. Requires service.type set to LoadBalancer.
   loadBalancerIP: ""