Introduce a parameter to set annotations for the external service

docs/accessing.md

@@ -129,7 +129,18 @@ Cassandra nodes. There are the following options:
   the native transport port on the nodes
 - EXTERNAL_RPC_PORT="9160" The external port that is forwarded to the rpc port
   on the nodes
+- EXTERNAL_SERVICE_ANNOTATIONS Annotations that are added to the external
+  service. E.g., this can be used to configure ExternalDNS access
 
 :warning: The external service definition will at the moment not be deleted if
 you set EXTERNAL_NATIVE_TRANSPORT and EXTERNAL_RPC to "false". If you need to
 remove external access, you have to remove the external service manually.
+
+### ExternalDNS annotations
+
+The EXTERNAL_SERVICE_ANNOTATIONS parameter can be used to set up ExternalDNS
+access when the external service is enabled. For example, one can set
+
+```
+EXTERNAL_SERVICE_ANNOTATIONS={"external-dns.alpha.kubernetes.io/hostname": "cassandra.example.org"}
+```

docs/parameters.md

@@ -117,6 +117,7 @@ Allow access to the Cassandra Cluster from outside Kubernetes.
 | **EXTERNAL_RPC**                   | This exposes the Cassandra cluster via an external service so it can be accessed from outside the Kubernetes cluster. Works only if START_RPC is true. | False   |
 | **EXTERNAL_NATIVE_TRANSPORT_PORT** | The external port to use for Cassandra native transport protocol.                                                                                      | 9042    |
 | **EXTERNAL_RPC_PORT**              | The external port to use for Cassandra rpc protocol.                                                                                                   | 9160    |
+| **EXTERNAL_SERVICE_ANNOTATIONS**   | Custom annotations for the external service.                                                                                                           |         |
 
 ## <a name="metrics"></a> Metrics Export
 

operator/params.yaml

@@ -338,6 +338,14 @@ parameters:
     default: "9160"
     group: external
 
+  - name: EXTERNAL_SERVICE_ANNOTATIONS
+    displayName: "External service annotations"
+    hint: "Key-Value Pairs of annotations."
+    type: map
+    description: "Custom annotations for the external service."
+    default:
+    group: external
+
   - name: BOOTSTRAP_TIMEOUT
     displayName: "Bootstrap Timeout"
     type: string

operator/templates/external-service.yaml

@@ -3,6 +3,8 @@ kind: Service
 metadata:
   name: {{ .Name }}-svc-external
   namespace: {{ .Namespace }}
+  annotations:
+    {{ toYaml .Params.EXTERNAL_SERVICE_ANNOTATIONS }}
 spec:
   type: LoadBalancer
   externalTrafficPolicy: Local

templates/operator/params.yaml.template

@@ -338,6 +338,14 @@ parameters:
     default: "9160"
     group: external
 
+  - name: EXTERNAL_SERVICE_ANNOTATIONS
+    displayName: "External service annotations"
+    hint: "Key-Value Pairs of annotations."
+    type: map
+    description: "Custom annotations for the external service."
+    default:
+    group: external
+
   - name: BOOTSTRAP_TIMEOUT
     displayName: "Bootstrap Timeout"
     type: string