doc: Clarify KUBERNETES_POD_NAME and KUBERNETES_NAMESPACE env variables

discovery-kubernetes-api/src/main/resources/reference.conf

@@ -24,6 +24,7 @@ akka.discovery {
     #
     # Set this value to a specific string to override discovering the namespace using pod-namespace-path.
     pod-namespace = "<pod-namespace>"
+    pod-namespace = ${?KUBERNETES_NAMESPACE}
 
     # Domain of the k8s cluster
     pod-domain = "cluster.local"

docs/src/main/paradox/bootstrap/kubernetes-api.md

@@ -28,7 +28,15 @@ The following configuration is required:
 
 The lookup needs to know which namespace to look in. By default, this will be detected by reading the namespace
 from the service account secret, in `/var/run/secrets/kubernetes.io/serviceaccount/namespace`, but can be overridden by
-setting `akka.discovery.kubernetes-api.pod-namespace`.
+setting `akka.discovery.kubernetes-api.pod-namespace` or by providing `KUBERNETES_NAMESPACE` environment variable.
+
+```yaml
+        env:
+        - name: KUBERNETES_NAMESPACE
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.namespace
+```
 
 For more details on how to configure the Kubernetes deployment see @ref:[recipes](recipes.md).
 

docs/src/main/paradox/rolling-updates.md

@@ -85,10 +85,26 @@ The following configuration is required, more details for each and additional co
 
 * `akka.rollingupdate.kubernetes.pod-name`: this can be provided by setting `KUBERNETES_POD_NAME` environment variable to `metadata.name` on the Kubernetes container spec.
 
+```yaml
+        env:
+        - name: KUBERNETES_POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
+```
+
 Additionally, the pod annotator needs to know which namespace the pod belongs to. By default, this will be detected by reading the namespace
 from the service account secret, in `/var/run/secrets/kubernetes.io/serviceaccount/namespace`, but can be overridden by
 setting `akka.rollingupdate.kubernetes.namespace` or by providing `KUBERNETES_NAMESPACE` environment variable.
 
+```yaml
+        env:
+        - name: KUBERNETES_NAMESPACE
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.namespace
+```
+
 #### Role based access control
 
 @@@ warning
@@ -217,10 +233,26 @@ The following configuration is required, more details for each and additional co
 
 * `akka.rollingupdate.kubernetes.pod-name`: this can be provided by setting `KUBERNETES_POD_NAME` environment variable to `metadata.name` on the Kubernetes container spec.
 
+```yaml
+        env:
+        - name: KUBERNETES_POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
+```
+
 Additionally, the pod annotator needs to know which namespace the pod belongs to. By default, this will be detected by reading the namespace
 from the service account secret, in `/var/run/secrets/kubernetes.io/serviceaccount/namespace`, but can be overridden by
 setting `akka.rollingupdate.kubernetes.namespace` or by providing `KUBERNETES_NAMESPACE` environment variable.
 
+```yaml
+        env:
+        - name: KUBERNETES_NAMESPACE
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.namespace
+```
+
 #### Role based access control
 
 Make sure to provide access to corresponding rbac rules `apiGroups` and `resources` like this: