database.go: remove hardcoded .svc.cluster.local dns suffix (#561)

* database.go: substitute hardcoded .svc.cluster.local dns suffix with config parameter

Use the pod's configured dns search path, for clusters where .svc.cluster.local is not correct.

docs/administrator.md

@@ -103,6 +103,12 @@ In this definition, the operator overwrites the account's name to match
 `pod_service_account_name` and the `default` namespace to match the target
 namespace. The operator performs **no** further syncing of this account.
 
+## Non-default cluster domain
+
+If your cluster uses a different dns domain than `cluster.local`, this needs
+to be set in the operator ConfigMap. This is used by the operator to connect
+to the clusters after creation.
+
 ## Role-based access control for the operator
 
 The `manifests/operator-service-account-rbac.yaml` defines cluster roles and

docs/reference/operator_parameters.md

@@ -159,6 +159,11 @@ configuration they are grouped under the `kubernetes` key.
   allowed. The default is
   `{username}.{cluster}.credentials.{tprkind}.{tprgroup}`.
 
+* **cluster_domain**
+  defines the default dns domain for the kubernetes cluster the operator is
+  running in. The default is `cluster.local`. Used by the operator to connect
+  to the postgres clusters after creation.
+
 * **oauth_token_secret_name**
   a name of the secret containing the `OAuth2` token to pass to the teams API.
   The default is `postgresql-operator`.