Review Request 58411: AMBARI-20726: Aggregate alert does not show status properly at Maintenance Mode change

[Qin Liu <qi...@gmail.com>]

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Review request for Ambari.


Bugs: AMBARI-20726
    https://issues.apache.org/jira/browse/AMBARI-20726


Repository: ambari


Description
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Aggregate alert does not show status properly at Maintenance Mode change.

Steps to reproduce:
Install a cluster that has HBase with one regionserver installed.

Scenario 1:
1. Turn On Maintenance Mode on the RegionServer or on the RegionServer host or on the HBase service.
2. Stop the RegionServer after that.
3. No red alerts will show as expected.
   Percent RegionServers Available - OK affected: [0], total: [1]
4. Now Turn Off Maintenance Mode, still keep the RegionServer down.
   But Percent RegionServers Available alert will still show "OK" - "CRIT" is expected.

Scenario 2:
1) Stop the RegionServer - Red alert will show as expected.
   Percent RegionServers Available - CRIT affected: [1], total: [1]
2) Now Turn On Maintenance Mode - For RegionServer status, Red alert will be gone as expected.
   But Percent RegionServers Available alert will still show "CRIT" - "OK" is expected.
   
The fix is to fire an AggregateAlertRecalculateEvent to refresh aggregate alert at Maintenance Mode change time.


Diffs
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  ambari-server/src/main/java/org/apache/ambari/server/events/listeners/alerts/AlertMaintenanceModeListener.java 847a207 
  ambari-server/src/main/java/org/apache/ambari/server/orm/dao/AlertsDAO.java d3ba2ac 
  ambari-server/src/test/java/org/apache/ambari/server/events/listeners/upgrade/AlertMaintenanceModeListenerTest.java bdc662a 


Diff: https://reviews.apache.org/r/58411/diff/1/


Testing
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The fix has been manually tested via HDP UI.
The unit testcase AlertMaintenanceModeListenerTest.java has been updated to reflect the change.

testrun_ambari-server Results :
Tests run: 4977, Failures: 0, Errors: 0, Skipped: 39

The skipped testcases has nothing to do with the fix.


Thanks,

Qin Liu