simple script to monitor hadoop daemon logs for errors and warning

#!/bin/sh
check_daemons=$1
log_dir=/var/log/hadoop
warn_file=/tmp/warnings.txt
emails="{email to send errors}"

rm -f /tmp/warnings.txt

for log_file in namenode jobtracker secondarynamenode datanode tasktracker
  do
     echo "$check_daemons" | grep -qw "$log_file"
     if [[ $? -eq 0 ]] ; then            
            echo -e "\n --------------------- $log_file errors and warning ------------------ \n" >> $warn_file
            cat $log_dir/hadoop-hadoop-$log_file-`hostname`.log.`date -d "1 day ago" +%Y-%m-%d` 
| egrep -v 'Checkpoint done' | egrep -A 10 'WARN|ERROR' >> $warn_file
     fi
done

error_line_count=`cat /tmp/warnings.txt | egrep -v "datanode errors and warning" |
 egrep -v "tasktracker errors and warning" | egrep -v "jobtracker errors and warning"
 | egrep -v "namenode errors and warning" | egrep -v "secondarynamenode errors and warning" | egrep -v "^$" | wc -l`

if [ $error_line_count != 0 ] ; then
   mail -s "`hostname` node errors and warnings" $emails < $warn_file
fi

The script can be cronned and it checks the logs from yesterday. You can easily modify the script for standalone runs for any specific dates

Usage:

For a node running namenode, jobtracker run script as

sh get_errors.sh namenode,jobtracker

For a node running datanode, tasktracker run script as

sh get_errors.sh datanode,tasktracker