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Install Monit on CentOS 6 From Source

Resources

Monit: http://mmonit.com/monit/
Wiki: http://mmonit.com/monit/documentation/monit.html
Man: http://linux.die.net/man/1/monit

Installation

Other packes I needed for my box

yum install pam-devel 
yum install openssl-devel

Get and install Monit

cd /usr/local/src
wget http://mmonit.com/monit/dist/monit-5.5.tar.gz
tar -zxvf monit-5.5.tar.gz
cd monit-5.5
./configure (If this fails, fix as necessary, then re-unpack the tar and try again)
make
make install

Setup monitrc

cp monitrc /etc/
vi /etc/monitrc
  # At the end of monitrc add or uncomment: include /etc/monit.d/*
  # Also set the 'set daemon' line at the beginning to your preferred interval.
mkdir /etc/monit.d

Create the service files (this will repeat for every service you monitor)

vi /etc/monit.d/apache

#Now Inside the apache file:

check process httpd with pidfile /var/run/httpd.pid
start program = "/etc/init.d/httpd start" with timeout 20 seconds
stop program = "/etc/init.d/httpd stop"
if failed host 127.0.0.1 port 80 protocol http
 and request "/index.html"
then restart
if 5 restarts within 5 cycles then timeout

check system localhost
if memory usage > 85% then alert
if cpu usage (user) > 80% for 3 cycles then alert
if cpu usage (system) > 80% for 3 cycles then alert

To see more services, check this out.

You can see in the above code we used alert. To setup alerts go into the /etc/monitrc file and do 2 things. First change the set mailserver line to localhost (or your mailserver). Then change the set alert line to include your email. Thats it.

Now setup the init.d file

cp contrib/rc.monit /etc/init.d/monit
chmod 755 /etc/init.d/monit

You may need to fix the line inside the above file thats pointing at /usr/bin/monit to /usr/local/bin/monit. After this is in place you should have the service monit restart command available.

To start Monit at boot, edit vim /etc/rc.d/rc.local and add in the next line

/usr/local/bin/monit -c /etc/monitrc -p /var/run/monit.pid -l /var/log/monit.log

Go ahead and run the above line in the console to see if monit works. If so, a call to service httpd stop should cause monit to restart apache.

Finished

Monit should be all setup. You can check with service monit status or ps aux | grep monit.

Another cool feature of monit is the web interface. Go to http://localhost:2812/ and enter the username and password form your monitrc file, it should look something like this, feel free to change it:

set httpd port 2812
  allow hauk:password

Main Files

/etc/monitrc - Monit's control file

/etc/monit.d/* - all services Monit will track

/etc/init.d/monit - service control file

/usr/local/src/monit-5.5 - source code

/usr/local/bin/monit

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