event_handler_template.sh

#!/bin/sh
#
# Event handler script for restarting the web server on the local machine
#
# Note: This script will only restart the web server if the service is
#       retried 3 times (in a "soft" state) or if the web service somehow
#       manages to fall into a "hard" error state.
#

# What state is the HTTP service in?
case "$1" in
OK)
    # The service just came back up, so don't do anything...
    ;;
WARNING)
    # We don't really care about warning states, since the service is probably still running...
    ;;
UNKNOWN)
    # We don't know what might be causing an unknown error, so don't do anything...
    ;;
CRITICAL)
    # Aha!  The HTTP service appears to have a problem - perhaps we should restart the server...
    # Is this a "soft" or a "hard" state?
    case "$2" in

    # We're in a "soft" state, meaning that Nagios is in the middle of retrying the
    # check before it turns into a "hard" state and contacts get notified...
    SOFT)

        # What check attempt are we on?  We don't want to restart the web server on the first
        # check, because it may just be a fluke!
        case "$3" in

        # Wait until the check has been tried 3 times before restarting the web server.
        # If the check fails on the 4th time (after we restart the web server), the state
        # type will turn to "hard" and contacts will be notified of the problem.
        # Hopefully this will restart the web server successfully, so the 4th check will
        # result in a "soft" recovery.  If that happens no one gets notified because we
        # fixed the problem!
        3)
            echo -n "Restarting HTTP service (3rd soft critical state)..."
            # Call the init script to restart the HTTPD server
            /etc/rc.d/init.d/httpd restart
            ;;
            esac
        ;;

    # The HTTP service somehow managed to turn into a hard error without getting fixed.
    # It should have been restarted by the code above, but for some reason it didn't.
    # Let's give it one last try, shall we?  
    # Note: Contacts have already been notified of a problem with the service at this
    # point (unless you disabled notifications for this service)
    HARD)
        echo -n "Restarting HTTP service..."
        # Call the init script to restart the HTTPD server
        /etc/rc.d/init.d/httpd restart
        ;;
    esac
    ;;
esac
exit 0