Setup Nagios

This Howto explains how to set up nagios, so you can monitor your server.

At first, you have to install the nagios2 package:

# apt-get update && apt-get install nagios2

You can't use the default apache-config-file which comes with nagios, because in ispCP, Websites have to be under /var/www.

So you have to create a directory there, /var/www/nagios and copy the contents of /usr/lib/cgi-bin/nagios2 and /usr/share/nagios2/htdocs into this directory.

# mkdir /var/www/nagios
# mkdir /var/www/nagios/cgi-bin /var/www/nagios/htdocs
# cp /usr/lib/cgi-bin/nagios2/* /var/www/nagios/cgi-bin/
# cp -R /usr/share/nagios2/htdocs/* /var/www/nagios/htdocs/

This directory has to be owned by the www-data - User:

# chown -R www-data.www-data /var/www/nagios

Now you can create a file /etc/apache2/sites-available/nagios2.conf with the following content:

#
# nagios Virtual Host Webinterface
#

<VirtualHost xxx.xxx.xxx.xxx:80>                           <-- insert your IP here
        ServerAdmin     admin@yourdomain.com               <-- insert your mail adress here
        DocumentRoot    /var/www/nagios/htdocs

        ServerName      nagios.yourdomain.com              <-- insert your domain here

        ErrorLog        /var/log/apache2/nagios.yourdomain.com-error.log  <-- dito
        CustomLog       /var/log/apache2/nagios.yourdomain.com-access.log combined  <-- dito

        ScriptAlias /cgi-bin/nagios2 /var/www/nagios/cgi-bin
        ScriptAlias /nagios2/cgi-bin /var/www/nagios/cgi-bin

        <Directory /var/www/nagios>
                Options FollowSymLinks

                DirectoryIndex index.html

                AllowOverride AuthConfig
                Order Allow,Deny
                Allow From All

                AuthName "Nagios Access"
                AuthType Basic
                AuthUserFile /etc/nagios2/htpasswd.users
                require valid-user
        </Directory>
</VirtualHost>

and enabled it via

# a2ensite nagios2.conf

In order to be able to run a subdomain like nagios.yourdomain.com you have to edit the file /etc/apache2/sites-available/ispcp.conf, go to the vhost-section of yourdomain.com and delete the *.yourdomain.com in this line:

ServerAlias     www.yourdomain.com yourdomain.com *.yourdomain.com

After all this, you have to reload the apache configuration:

# /etc/init.d/apache2 reload

In the file /etc/nagios2/cgi.cfg you have to change the values physical_html_path and url_html_path as shown below:

physical_html_path=/var/www/nagios/htdocs
url_html_path=/

Now you have to create a password file for nagios which has to be placed under /etc/nagios2/htpasswd.users:

# htpasswd -c /etc/nagios2/htpasswd.users nagiosadmin
New password:
Re-type new password:

Now, you should be able to access nagios via http://nagios.yourdomain.com, login with the username nagiosadmin and the password specified under 4.

The nagios configuration is done under /etc/nagios2/, you find the nagios documentation here: http://nagios.sourceforge.net/docs/2_0/