Bash Script To Monitor and Restart Service on RHEL 7 or CentOS 7

Overview

The purpose of this bash script is to monitor a specific service that needs to be running at all times. In case the service is not running, the script will restart the service and send out notification to the recipients.

Applies To

Tested on RHEL 7, CentOS 7

Pre-requisites

·        mailx package has to be installed

Bash Script Snippet

#!/bin/bash

#

# This script check’s the status of the service, restart and notify Recipients

#

# Environment Variables

#

HOST_NAME=`hostname`

SERVICE_NAME=httpd.service

EMAIL_TO=RecipentsMailAddress@domain.com

ExecutedBy=`who am i`

#

# Verify if the service status is active or inactive state

#

if [ `systemctl is-active ${SERVICE_NAME}` != "active" ]

then

    echo "$SERVICE_NAME is not running on $HOST_NAME restarting it"

    systemctl restart ${SERVICE_NAME}

    Exit_Code=`echo $?`

    if [ ${Exit_Code} = "0" ]; then

# Send EMail Notification

       mail -s "${SERVICE_NAME} was restarted on ${HOST_NAME}" ${EMAIL_TO} <<< "${SERVICE_NAME} was restarted on ${HOST_NAME} run by ${ExecutedBy}"

    exit 0

    fi

fi

exit 0

#

# End of script

Execute Script

This script can be run in 2 ways; manually and via cronjob

First step is to add execute permission to the shell script, only once.

chmod +x /usr/bin/RestartServiceIfDown

Execute Script - Manually

To run the script manually, run the command;

/usr/bin/RestartServiceIfDown

Execute Script - Cronjob

You can alternatively, add this script to a cronjob to check as service state at regular intervals.

In order monitor the service with cronjob, add a crontab entry.

crontab snippet

# Check httpd.service Status and restart if inactive

*/15 * * * * /usr/bin/RestartServiceIfDown > /dev/null 

Now every 15 minutes the script should run, check the service is running and if not restart it for you.

Note:

1)      Email Notification will be sent only upon restarting of service

2)      If the service is restarting frequently, you need to verify the cause and fix the issue accordingly

E-Mail Notification

E-Mail notification will be sent on both the methods of execution.

Slideshare Information

Guide to utilize the bash script and configure is uploaded with screenshots.