zaplatynski / checkmk-vagrant

A Ubuntu/Trusty64 Vagrant Box for check-mk-raw-1.2.6p12_0.trusty_amd64

Getting started

git clone https://github.com/baccenfutter/checkmk-vagrant
cd checkmk-vagrant
vagrant up
vagrant ssh

Once the Vagrant box has spun up successfully a new site must be created

sudo omd create <site-name>

Once a site has been created it can be configured.

sudo omd stop <site-name>
sudo omd config <site-name>

Under Basic choose the Icinga core as it has some improvements over the classic Nagios core.

Don't forget to restart the site:

sudo omd start <site-name>

Now that the site is configured and running, let's su into it:

sudo omd su <site-name>
omd status
exit

Installing the agent

Inside the checkmk-vagrant box, issue:

sudo dpkg -i /opt/omd/versions/1.2.6p12.cre/share/check_mk/agents/check-mk-agent_1.2.6p12-1_all.deb

Now navigate to the web-ui of the checkmk-vagrant box. It will have received an address from your local DHCP server. http://<ip>/<site-name>/

The default credentials for OMD are:

• username: omdadmin
• password: omd

In order to add a host:

• In the sidebar, go to the WATO main menu, click hosts, click add a new host.
• As a hostname choose localhost, as we will monitor the agent running on the vagrant box itself. You can leave all the other settings and host-tags as is.
• Click Save and go to services
• Click save manual check configuration
• Activate your changes!

Command-line Interface

First, we need to navigate to the OMD site:

sudo omd su <site-name>

To query localhost for all check results:

cmk -nv localhost

In order to take a look at the site's monitoring configuration (hosts, services, etc)

cmk -D

Let's directly query localhost's agent:

cmk -d localhost

It is also possible to run an inventory check on localhost The inventory check will query the agent for any newly discovered checks that may want to be inventorized.

cmk -I localhost

Writing an own agent plugin

Extending the agent with plugins is a twofold process.

• The agent needs to be extended to output a new section containing all infos
• The server needs to be extended to be able to check and inventorize this new section.

Scenario

Assume we have a random service daemon that writes the agent's coffee level to the file /coffee on every host.

In the first step, we extend the agent to output an additional section with the contents of the coffee-file. Run the following code on the vagrant box, but not inside the OMD site:

sudo cat <<EOF > /usr/lib/check_mk_agent/plugins/coffee
#!/bin/bash

# Maintain a reference to the coffee-file.
coffee_file=/coffee

# Output the section header.
echo "<<<coffee>>>"

# Output the contents of the coffee-file or 0 if it doesn't exist.
if [[ -r "$coffee_file" ]]; then
        cat "$coffee_file"
else
        echo 0
fi
EOF

chmod +x /usr/lib/check_mk_agent/plugins/coffee

In the second step, we extend the server to inventorize and check the new <<<coffee>>> section.

sudo omd su <site-name>
cat <<EOF > local/share/check_mk/checks/coffee
default_thresholds = 50, 25


def inventory_coffe(info):
    return [('Current Coffee Level', None)]


def check_coffee(item, params, coffee_level):
    try:
        warn, crit = params
    except:
        warn, crit = default_thresholds
    
    try:
        coffee_level = int(coffee_level[0][0])
    except:
        return (
            3,              # 3 equals state: unknown
            '#clueless'     # An additional description
        )

    if coffee_level < crit:
        return (
            2,              # 2 equals state: critical
            '#fixme',       # An additional description
        )

    if coffee_level < warn:
        return (
            1,              # 1 equals state: warning
            '#danger',      # An additional description
        )

    return (
        0,                  # 0 equals state: ok
        '#thereifxiedit'    # An additional description
    )

check_info["coffee.level"] = (
    check_coffee,           # Check function within this module
    "Current Coffee Level", # Service description
    0,                      # Comes with perf-data
    inventory_coffe,        # Inventory function
)

EOF

cmk -I localhost
cmk -R
cmk -nv localhost | grep coffee