In the following steps I will demonstrate how to install the check_mk agent, install the check_apachestatus_auto.pl script and dependencies, add the proper stanza for server-status to aegir and finally add the check into mrpe (check_mk replacement for nrpe).
Assumptions: RedHat/CentOS/Scientific Linux, 64-bit, EPEL, Aegir, root access.
# Install check_mk agent:
*First install the check_mk agent rpm:
yum install http://mathias-kettner.de/download/check_mk-agent-1.2.0p3-1.noarch.rpm --nogpg*We don't want just anyone to poll the data from check_mk, so modify the /etc/xinetd.d/check_mk by adding the ip of your nagios server to the 'only_from' line:
only_from = 127.0.0.1 nagios_server_ip*The check_mk agent operates through xinetd on port 6556, verify that xinetd will start at boot, and make sure it is currently running:
chkconfig xinetd on ; service xinetd start*Hopefully you are running a firewall, to poke a hole in an iptables based firewall you can add a rule similar to:
-A INPUT -s nagios_server_ip -p tcp -m tcp --dport 6556 -j ACCEPTto /etc/sysconfig/iptables, then restart iptables with the service command:
service iptables restart# Install the check_apachestatus_auto.pl plugin
* Install the nagios-plugins-perl rpm from EPEL, this will provide the /usr/lib64/nagios/plugins/utils.pm file, as well as creating a directory structure:
yum install nagios-plugins-perl* Download plugin from http://blog.spreendigital.de/nagios/?#check_apachestatus_auto to /usr/lib64/nagios/plugins, modify it to find utils.pm in /usr/lib64/nagios/plugins:
wget -O /tmp/check_apachestatus_auto.tgz http://blog.spreendigital.de/wp-content/uploads/2009/07/check_apachestatus_auto.tgz tar zxvf /tmp/check_apachestatus_auto.tgz -C /usr/lib64/nagios/plugins/ sed -i 's/\/usr\/local\/nagios\/libexec/\/usr\/lib64\/nagios\/plugins/g' /usr/lib64/nagios/plugins/check_apachestatus_auto.pl# Modify apache to display server-status
* Typically you could enable server-status by un-commenting the correct stanza in /etc/httpd/conf/httpd.conf, but with an aegir system any get request for http://localhost/server-status will be fulfilled by aegir. If you do some digging you will fine the /var/aegir/config/server_master/apache/pre.d directory which is included before any virtual hosts, this is where you need to put a config file for server-status.
cat << EOF >> /var/aegir/config/server_master/apache/pre.d/nagios.conf
<VirtualHost *:80>
ServerName localhost
<Location /server-status>
SetHandler server-status
Order deny,allow
Deny from all
Allow from 127.0.0.1
</Location>
</VirtualHost>
EOF
* Reload apache to read your new config file:
service httpd reload* Verify it's working using curl, this should dump the raw html from the server-status page to your screen:
curl localhost/server-status# Setup mrpe to execute the plugin
* This is one of the easier steps, simply create /etc/check_mk/mrpe.cfg, and add a line with the check alias and location:
mkdir /etc/check_mk echo "Apache_Status /usr/lib64/nagios/plugins/check_apachestatus_auto.pl -H localhost" >> /etc/check_mk/mrpe.cfg# Now that we have installed the check_mk agent, the check_apachestatus_auto.pl script and the mrpe.cfg file you can re-inventory the node from your check_mk server, note the mrpe line in the following output:
cpu.loads 1 new checks cpu.threads 1 new checks df 7 new checks diskstat 1 new checks kernel 3 new checks kernel.util 1 new checks lnx_if 1 new checks mem.used 1 new checks mounts 7 new checks mrpe 1 new checks ntp.time 1 new checks postfix_mailq 1 new checks tcp_conn_stats 1 new checks uptime 1 new checks# Once you have reloaded nagios, check_mk will watch the server-status page and produce nice graphs like this:
