rails_check.sh

#!/bin/bash
#
# This script is triggered by crontab every 5 minutes.
# Logs to /var/log/ui-server/<host>-rails_check.log.

log_dir=/var/log/my_rails_app
mkdir -p $log_dir
log_file=$log_dir/$(hostname)-rails_check.log

# Limits in MB
SOFT_LIMIT=700
MIDD_LIMIT=900
HARD_LIMIT=1100

for i in `pgrep  -f Rack`; do
   mem=`ps -o rss= -p $i`
   [ -z "$mem" ] && continue
   if [ "$mem" -gt $(($HARD_LIMIT*1000)) ]; then
     echo "$(date) PID $i exceeds hard memory limit (>${HARD_LIMIT}MB)." >> $log_file
     kill -KILL $i
   elif [ "$mem" -gt $(($MIDD_LIMIT*1000)) ]; then
     echo "$(date) PID $i exceeds memory limit (>${MIDD_LIMIT}MB)." >> $log_file
     kill -TERM $i
   elif [ "$mem" -gt $(($SOFT_LIMIT*1000)) ]; then
     echo "$(date) PID $i exceeds soft memory limit (>${SOFT_LIMIT}MB)." >> $log_file
     kill -USR1 $i
   fi
done