= Checkmk =

Next generation monitoring.

== Software ==

To get all the dependencies a small helper program is installed.

{{{
apt-get install gdebi
}}}

Download the checkmk package from the checkmk [[https://checkmk.com/download?edition=cre&version=stable&dist=debian&os=buster|download page]]

{{{
wget https://download.checkmk.com/checkmk/2.0.0/check-mk-raw-2.0.0_0.buster_amd64.deb
gdebi check-mk-raw-2.0.0_0.buster_amd64.deb
}}}

Create a site and start it
{{{
omd create monitor
omd start monitor
}}}

== Checkmk Agent ==

Install the agent on the system that should be monitored. Let `xinetd` handle it.
{{{
apt-get install xinetd
wget http://checkmk/monitor/check_mk/agents/check-mk-agent_2.0.0-1_all.deb
dpkg -i check-mk-agent_2.0.0-1_all.deb
}}}

=== Apt ===
Download the APT plugin from the server and place it in `/usr/lib/check_mk_agent/plugins`. Make sure it is executeable.
{{{
chmod 755 /usr/lib/check_mk_agent/plugins/mk_apt
}}}
 
=== Mariadb ===

Copy the `mk_mysql` plugin into /usr/lib/check_mk_agent/plugins/ and make it executeable
{{{
cd http://checkmk/monitor/check_mk/agents/plugins/mk_mysql
http://checkmk/monitor/check_mk/agents/plugins/mk_mysql
chmod 755 mk_mysql
}}}

Create the file `/etc/check_mk/mysql.cfg` and configure a user for mariadb authentication
{{{
[client]
user=checkmk
password=checkmkpassword
}}}

=== Openwrt ===

Log in to your openwrt device, download the check_mk_agent and make it executeable
{{{
opkg install curl
curl http://checkmk/monitor/check_mk/agents/check_mk_agent.openwrt > /usr/bin/check_mk_agent
chmod +x /usr/bin/check_mk_agent
}}}

Create ssh keys for the checkmk user, and copy the public key to your openwrt device and place it in `/etc/dropbear/authorized_keys`
{{{
su - monitor
ssh-keygen -t rsa
scp /omd/sites/monitor/.ssh/id_rsa.pub root@192.168.1.13:/etc/dropbear/authorized_keys
}}}

== DNS Cache ==

Checkmk maintains a DNS cache. If a host changes its IP-address, checkmk will not know this. The solution is to update the DNS cache.
{{{
su - monitor
/opt/omd/versions/2.0.0p1.cre/bin/check_mk --update-dns-cache
}}}

Another option is to go to `Setup -> General -> Global settings -> Execution of checks -> Use DNS lookup cache` and disable that feature.

== References ==

 * https://docs.checkmk.com/latest/en/intro.html
 * https://forum.checkmk.com/t/how-to-install-check-mk-agent-for-openwrt/18073
 * https://forum.openwrt.org/t/solved-ssh-key-authentification-vs-dropbear/17624