Shell script to monitor Cassandra Database via 'nodetool status' command

Below is the script to monitor the Cassandra Database nodes with nodetool status command.

Schedule to run the script at certain frequency with crontab, possible every 5 Minutes.

#!/bin/bash

#######
# Author : Pramod P
# Purpose: Monitor Cassandra instance
# Date : Created Date
#######


PRIMARY_DBA="primary@primary.com"
ON_CALL_DBA="oncall@oncall.com"
#Create a temporary file with under maintenance with empty content. And uncomment below line when doing some maintenance.
#$MAINT_LOC=/path/to/tmpfile

#Monitor if the node is under maintenance.
if [ -f $MAINT_LOC/under_maintenance ]
then
        echo "==========================="
        echo "$MAINT_LOC/under_maintenance file exists."
        echo "Monitoring script detected so Cassandra instance is in maintenance mode.  Cassandra will not be monitored."
        exit 1
fi

# Monitor Cassandra nodes by nodetool.
DOWN_NO=`/usr/bin/nodetool status | grep UD | wc -l`
echo $DOWN_NO
if [ $DOWN_NO -gt 0 ]
then
        DOWN_HOST=`/usr/bin/nodetool status | grep UD | awk '{print $2}'`
        printf "\n\nCassandra Instance is not running on $DOWN_HOST" | mail -s "Attention >> Cassandra Instance is down on Production" $PRIMARY_DBA $ON_CALL_DBA
        exit 1
fi

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