check_hadoop_namenode.pl (Advanced Nagios Plugins Collection)

Part of the Advanced Nagios Plugins Collection, download it here:

https://github.com/harisekhon/nagios-plugins

./check_hadoop_namenode.pl --help

Nagios Plugin to run various checks against the Hadoop HDFS Cluster via the Namenode JSP pages

This is an alternate rewrite of the functionality from my previous check_hadoop_dfs.pl plugin
using the Namenode JSP interface instead of the hadoop dfsadmin -report output

Recommend to use the original check_hadoop_dfs.pl plugin it's better tested and has better/tighter output validation than this one, but this one is useful for the following reasons:
1. you can check your NameNode remotely via JSP without having to adjust the NameNode setup to install the check_hadoop_dfs.pl plugin
2. it can check Namenode Heap Usage

Caveats:
1. Cannot currently detect corrupt or under-replicated blocks since JSP doesn't offer this information
2. There are no byte counters, so we can only use the human summary and multiply out, and being a multiplier of a summary figure it's marginally less accurate

Note: This was created for Apache Hadoop 0.20.2, r911707 and updated for CDH 4.3 (2.0.0-cdh4.3.0). If JSP output changes across versions, this plugin will need to be updated to parse the changes

usage: check_hadoop_namenode.pl [ options ]

-H --host Namenode to connect to
-P --port Namenode port to connect to (defaults to 50070)
-s --hdfs-space Checks % HDFS Space used against given warning/critical thresholds
-r --replication Checks replication state: under replicated blocks, blocks with corrupt replicas, missing blocks. Warning/critical thresholds apply to under replicated blocks. Corrupt replicas and missing blocks if any raise critical since this can result in data loss
-b --balance Checks Balance of HDFS Space used % across datanodes is within thresholds. Lists the nodes out of balance in verbose mode
-m --node-count Checks the number of available datanodes against the given warning/critical thresholds as the lower limits (inclusive). Any dead datanodes raises warning
-n --node-list List of datanodes to expect are available on namenode (non-switch args are appended to this list for convenience). Warning/Critical thresholds default to zero if not specified
--heap-usage Check Namenode Heap % Used. Optional % thresholds may be supplied for warning and/or critical
-w --warning Warning threshold or ran:ge (inclusive)
-c --critical Critical threshold or ran:ge (inclusive)
-h --help Print description and usage options
-t --timeout Timeout in secs (default: 10)
-v --verbose Verbose mode
-V --version Print version and exit