check_hadoop-dfs.sh

Description
Highly work in progress since I'm currently occupied with kicking off a large Hadoop cluster and the checks are written en passant. Please note that there's a small shell snippet that needs to be sudo'd by the Nagios user to get the actual dfs statistics. This is because I didn't want to give hadoop related permissions to the Nagios user.
Put the small snippet attached below in a directory of your choice (configurable via -s/--path-sh), but name it get-dfsreport.sh and make it read, write and accessible by root only. Then enable the Nagios user via /etc/sudoers (or better visudo) to run the script.

-h/--help Output
check_hadoop-dfs.sh is a Nagios plugin to check the status of HDFS, Hadoop's underlying, redundant, distributed file system.

check_hadoop-dfs.sh -s /usr/local/sbin [-w 10] [-c 5]

Options:
-s|--path-sh)
Path to the shell script that is mentioned in the
documentation. Default is: /usr/local/sbin
-w|--warning)
Defines the warning level for available datanodes. Default is: off
-c|--critical)
Defines the critical level for available datanodes. Default is: off

Output Example
user@host: ~ $ ./check_hadoop-dfs.sh -s /var/nagios/home/bin
OK - Datanodes up and running: 50, DFS total: 20147365 MB, DFS used: 0 MB (0%) | 'datanodes_available'=50 'dfs_total'=20147365 'dfs_used'=0
user@host: ~ $ ./check_hadoop-dfs.sh -s /var/nagios/home/bin -w 40 -c 30
OK - Datanodes up and running: 50, DFS total: 20147365 MB, DFS used: 0 MB (0%) | 'datanodes_available'=50 'dfs_total'=20147365 'dfs_used'=0
user@host: ~ $ ./check_hadoop-dfs.sh -s /var/nagios/home/bin -w 60 -c 40
WARNING - Datanodes up and running: 50, DFS total: 20147365 MB, DFS used: 0 MB (0%) | 'datanodes_available'=50 'dfs_total'=20147365 'dfs_used'=0
user@host: ~ $ ./check_hadoop-dfs.sh -s /var/nagios/home/bin -w 70-c 60
CRITICAL - Datanodes up and running: 50, DFS total: 20147365 MB, DFS used: 0 MB (0%) | 'datanodes_available'=50 'dfs_total'=20147365 'dfs_used'=0
user@host: ~ $ ./check_hadoop-dfs.sh -s /var/nagios/home/bin -w 20 -c 40
Please adjust your warning/critical thresholds. The warning must be higher than the critical level!
user@host: ~ $ ./check_hadoop-dfs.sh -s /var/nagios/home/bin -w 30
Please also set a critical value when you want to use warning/critical thresholds!
user@host: ~ $ ./check_hadoop-dfs.sh -s /var/nagios/home/bin -c 30
Please also set a warning value when you want to use warning/critical thresholds!