YARN-8845. Removed unused hadoop.registry.rm reference.

            Contributed by Íñigo Goiri

(cherry picked from commit bf04f194568f9e81f5481b25a84ad903e3c307cf)

hadoop-common-project/hadoop-common/src/main/resources/core-default.xml

@@ -2669,22 +2669,6 @@
 
   <!-- YARN registry -->
 
-  <property>
-    <name>hadoop.registry.rm.enabled</name>
-    <value>false</value>
-    <description>
-      Is the registry enabled in the YARN Resource Manager?
-
-      If true, the YARN RM will, as needed.
-      create the user and system paths, and purge
-      service records when containers, application attempts
-      and applications complete.
-
-      If false, the paths must be created by other means,
-      and no automatic cleanup of service records will take place.
-    </description>
-  </property>
-
   <property>
     <name>hadoop.registry.zk.root</name>
     <value>/registry</value>

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-registry/src/main/java/org/apache/hadoop/registry/client/api/RegistryConstants.java

@@ -50,17 +50,6 @@ public interface RegistryConstants {
    */
   String DNS_PREFIX = REGISTRY_PREFIX + "dns.";
 
-  /**
-   * flag to indicate whether or not the registry should
-   * be enabled in the RM: {@value}.
-   */
-  String KEY_REGISTRY_ENABLED = REGISTRY_PREFIX + "rm.enabled";
-
-  /**
-   * Defaut value for enabling the registry in the RM: {@value}.
-   */
-  boolean DEFAULT_REGISTRY_ENABLED = false;
-
   /**
    * flag to indicate whether or not the registry should
    * be enabled in the RM: {@value}.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/registry/registry-configuration.md

@@ -36,51 +36,6 @@ the values, so enabling them to read from and potentially write to the registry.
 ## Core Settings
 
 
-### Enabling the Registry in the Resource Manager
-
-The Resource Manager manages user directory creation and record cleanup
-on YARN container/application attempt/application completion.
-
-```
-  <property>
-    <description>
-      Is the registry enabled in the YARN Resource Manager?
-
-      If true, the YARN RM will, as needed.
-      create the user and system paths, and purge
-      service records when containers, application attempts
-      and applications complete.
-
-      If false, the paths must be created by other means,
-      and no automatic cleanup of service records will take place.
-    </description>
-    <name>hadoop.registry.rm.enabled</name>
-    <value>false</value>
-  </property>
-```
-
-If the property is set in `core-site.xml` or `yarn-site.xml`,
-the YARN Resource Manager will behave as follows:
-1. On startup: create the initial root paths of `/`, `/services` and `/users`.
-  On a secure cluster, access will be restricted to the system accounts (see below).
-2. When a user submits a job: create the user path under `/users`.
-3. When a container is completed: delete from the registry all service records
-   with a `yarn:persistence` field of value `container`, and a `yarn:id` field
-   whose value matches the ID of the completed container.
-4. When an application attempt is completed: remove all service records with
-   `yarn:persistence` set to `application-attempt` and `yarn:id` set to the
-   pplication attempt ID.
-5. When an application finishes: remove all service records with
-   `yarn:persistence` set to `application` and `yarn:id` set to the
-   application ID.
-
-All these operations are asynchronous, so that zookeeper connectivity problems
-do not delay RM operations or work scheduling.
-
-If the property `hadoop.registry.rm.enabled` is set to `false`, the RM will
-not interact with the registry —and the listed operations will not take place.
-The root paths may be created by other means, but service record cleanup will not take place.
-
 ### Setting the Zookeeper Quorum: `hadoop.registry.zk.quorum`
 
 This is an essential setting: it identifies the lists of zookeeper hosts
@@ -326,17 +281,6 @@ concluding that the quorum is unreachable and failing.
 ```
   <!-- YARN registry -->
 
-  <property>
-    <description>
-      Is the registry enabled: does the RM start it up,
-      create the user and system paths, and purge
-      service records when containers, application attempts
-      and applications complete
-    </description>
-    <name>hadoop.registry.rm.enabled</name>
-    <value>false</value>
-  </property>
-
   <property>
     <description>
       A comma separated list of hostname:port pairs defining the

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/registry/yarn-registry.md

@@ -379,21 +379,6 @@ lack this string before attempting to parse the data with a JSON parser.
 
 ### YARN Persistence policies
 
-The YARN Resource Manager integration integrates cleanup of service records
-as an application, attempt or container is completed.
-
-This allows service to register entries which have a lifespan bound to one of
-these aspects of YARN applications' lifecycles. This is a feature which is only
-supported when the RM has had its registry integration enabled via the
-configuration option `hadoop.registry.rm.enabled`.
-
-If this option is enabled, and the YARN resource manager is running,
-it will clean up service records as defined
-below.
-
-If the option is disabled, the RM does not provide any registry support at all.
-
-
 The attributes, `yarn:id` and `yarn:persistence` specify which records
 *and any child entries* may be deleted as the associated YARN components complete.