Yesha Vora created YARN-4101:

             Summary: RM should print alert messages if Zookeeper and 
Resourcemanager gets connection issue
                 Key: YARN-4101
             Project: Hadoop YARN
          Issue Type: Bug
          Components: yarn
            Reporter: Yesha Vora
            Priority: Critical

Currently, There is no way for user to understand Zk-RM has connection issues. 
In HA environment, RM is highly dependent on Zookeeper. If connection between 
RM and Zk is jeopardized, cluster is likely to be gone in bad state.

Example: Rm1 is active and Rm2 is standby. If connection between Rm2 and Zk is 
lost, Rm2 will never become active. In this case, if Rm1 hits an error and 
could not be started, cluster goes in bad state. This situation is very hard to 
debug for user. In this case, if we can develop better prompting of messages, 
User could fix the Zk-RM connection issue and could avoid getting in bad state.

Thus, We need a better way to prompt alert to user if connection between Zk -> 
Active RM or Zk -> standby RM is getting bad.
Here are the suggestions.
1) Print connection lost alert in RM UI
2) Print alert messages while running any Yarn command such as yarn logs, yarn 
applications etc

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