[jira] [Created] (HBASE-21126) Add ability for HBase Canary to ignore a configurable number of ZooKeeper down nodes

["David Manning (JIRA)" <ji...@apache.org>]

David Manning created HBASE-21126:
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             Summary: Add ability for HBase Canary to ignore a configurable number of ZooKeeper down nodes
                 Key: HBASE-21126
                 URL: https://issues.apache.org/jira/browse/HBASE-21126
             Project: HBase
          Issue Type: Improvement
          Components: canary, Zookeeper
    Affects Versions: 2.0.0, 1.0.0, 3.0.0
            Reporter: David Manning
             Fix For: 3.0.0, 2.0.0, 1.3.0


When running org.apache.hadoop.hbase.tool.Canary with args -zookeeper -treatFailureAsError, the Canary will try to get a znode from each ZooKeeper server in the ensemble. If any server is unavailable or unresponsive, the canary will exit with a failure code.

If we use the Canary to gauge server health, and alert accordingly, this can be too strict. For example, in a 5-node ZooKeeper cluster, having one node down is safe and expected in rolling upgrades/patches.

This is a request to allow the Canary to take another parameter
{code:java}
-permittedZookeeperFailures <N>{code}
If N=1, in the 5-node ZooKeeper ensemble example, then the Canary will still pass if 4 ZooKeeper nodes are reachable, but fail if 3 or fewer are reachable.

(This is my first Jira posting... sorry if I messed anything up.)



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