k8s append_hash (#48830)

* Add append_hash functionality to k8s module

append_hash adds a hash based on the contents of a ConfigMap
or Secret to the name - this enables immutable ConfigMaps and
Secrets.

* Provide k8s_config_resource_name plugin

The k8s_config_resource_name filter plugin provides a means of determining
the name of ConfigMaps and Secrets created with append_hash

* Add changelog fragment

* fix failing tests

* Update openshift version needed for append_hash

docs/docsite/rst/user_guide/playbooks_filters.rst

@@ -1083,6 +1083,32 @@ To escape special characters within a regex, use the "regex_escape" filter::
     {{ '^f.*o(.*)$' | regex_escape() }}
 
 
+Kubernetes Filters
+``````````````````
+
+Use the "k8s_config_resource_name" filter to obtain the name of a Kubernetes ConfigMap or Secret,
+including its hash::
+
+    {{ configmap_resource_definition | k8s_config_resource_name }}
+
+This can then be used to reference hashes in Pod specifications::
+
+    my_secret:
+      kind: Secret
+      name: my_secret_name
+
+    deployment_resource:
+      kind: Deployment
+      spec:
+        template:
+          spec:
+            containers:
+            - envFrom:
+                - secretRef:
+                    name: {{ my_secret | k8s_config_resource_name }}
+
+.. versionadded:: 2.8
+
 Other Useful Filters
 ````````````````````