Easy guide to monitoring your systems with Checkmk

This tutorial will show you how to take your first steps with Checkmk, a comprehensive IT monitoring system that identifies issues across your entire IT infrastructure. Checkmk monitors servers, applications, networks, cloud environments and many other systems. I will show you how to install Checkmk on Ubuntu 20.04 and add hosts (systems to be monitored) to the monitoring. Checkmk also runs on other Linux distributions such as Debian, RHEL, CentOS or SLES, in a Docker container, or also as a virtual appliance. You can download the latest version for all platforms from the official Checkmk website. For this tutorial I will use the Checkmk Raw Edition, which is completely open source.

The goal of this article is to give you a quick start into Checkmk and the world of IT monitoring. Checkmk comes with numerous powerful features, and I recommend checking the documentation online for further reference. You will see that it is fairly easy to set up a first monitoring, as many configuration tasks are performed automatically, and thanks to the around 2,000 official monitoring plug-ins, Checkmk supports many systems right out of the box.

Prerequisites

If you use an Ubuntu server, it should at least be on version 16.04 or higher to host your monitoring. The Ubuntu server I used has 4 CPU cores and 8 GB RAM, which is more than enough for a small monitoring environment. You also need a client to download Checkmk and send the package to your host server. The client must also have root access to your monitoring host server.

Download the Checkmk Raw Edition

There are two options for using Checkmk for free: You can go for the Checkmk Raw Edition which is completely open source, or start with the Checkmk Free Edition. The Free Edition allows you to test all of the additional features included with the Enterprise Edition. After 30 days, the Free Edition will be limited to 25 hosts. This tutorial uses the Raw Edition.

  • Go to the download section on the Checkmk website.
  • Select the Checkmk Raw Edition, take the latest stable version (this tutorial is based on version 2.0.0p8), choose your platform and your OS version. You should now have all four boxes checked.
  • Click the download button to download the package.
  • Now you need to send the data to your Linux server. You can use the scp command. In this tutorial the IP address of the server is 10.0.3.15
    scp check-mk-raw-2.0.0p8_0.focal_amd64.deb [email protected]:/tmp
  • All further actions will happen on the Linux server. Log in as root using the command ssh on the same server.
    ssh [email protected]

Installing the Checkmk package

  • Now you need to install the package, including all of its dependencies. I used apt install. Please note that you should add the path to the .deb file after apt install.
    apt install /tmp/check-mk-raw-2.0.0p8_0.focal_amd64.deb
  • Once the installation has completed,, you can test the installation. The command omd should be accessible now, and you should be able to use this command.
    omd version

Screenshot from the terminal for omd version

OMD is short for Open Monitoring Distribution, an open source project founded by Checkmk founder Mathias Kettner. Checkmk uses OMD for instance management.

Creating a first Checkmk monitoring site

  • The next step is to create and start a first Checkmk site (a site as in instance). Make sure you are still root and use omd create. This tutorial named the site 'checkmk_demo', but you can use a name of your choice and add it to the omd create command.
    omd create checkmk_demo
  • Now on your screen you should be able to see the information about how to start and access your site. You could follow the steps to change your admin password right now here on the terminal, but I prefer to do that in the Checkmk user interface. So, copy the randomly generated password and simply start your instance with omd start and the name of the site.
    omd start checkmk_demo

At this point, you are done on the terminal, and this tutorial will continue on the Checkmk user interface. With these last few steps, a few things will have happened in the background: On your server you created a new user (this user is known as the site user), and a group with the name of the site. A directory for the site is created under /omd/sites, (e.g.
/omd/sites/checkmk_demo). Checkmk also copied its default configuration into the new directory and a user with the name 'cmkadmin' has been created for the Checkmk web interface.

Changing your password in the user interface

  • Open the link to your Checkmk site in your browser. You can open the link shown on your terminal. Every Checkmk site has its own URL that is composed of the IP address or host name of your monitoring server and the name of the site.
  • Log in with 'cmkadmin' and the password copied before. You will see an empty dashboard.
  • Go to 'User' in the sidebar on the left and click on 'Change password' under 'Profile'. Here you can change your password.

No one can force you to change the password, of course, but I really recommend it. It´s just a few clicks and you can use a strong password to secure the access to your monitoring.

Add hosts to your Checkmk site

In this tutorial I will show you how to use the Checkmk agents, which is a very efficient method for server monitoring.

As a first host, you should add the server you are hosting your monitoring on. Checkmk supports several ways of monitoring servers, and the best method for server monitoring is usually by using the Checkmk agents. In the sidebar on the left, you will find a button with a gearwheel called Setup. This is the place where all of the configuration is performed, and you will also find the monitoring agents there.

  • Click on Setup > Agents > Linux
  • Select the package for your operating system to download it. For my Ubuntu server, I downloaded the .deb package and installed it like any other package on my monitoring server.

Checkmk comes with agents for several systems

You can test if the agent works by running the check_mk_agent command in the terminal on your server. You should then see the agent output.

  • Once the agent has been installed, go to Setup > Hosts and then click on 'Add host'.
  • Add the name of your server under 'Hostname'. If you have DNS set up in your network, then Checkmk can resolve the IP address for your host name automatically. Otherwise, add the IP address by clicking the checkbox next to 'IPv4 Address', then entering it there. If you add an IP address, you can choose any host name you like. Leave the other areas unaltered.

Adding a host in Checkmk takes just a few clicks

  • Click on 'Save & go to service configuration'. Checkmk will now automatically discover any relevant monitoring services on that host and you should see a list of undecided services. Checkmk will also automatically add labels depending on the type of device.
  • Click on 'Fix all' to monitor all of these. That will add all of the detected services and host labels to the monitoring and will also remove services that have 'vanished'. You can manage the services manually, of course, but this way is a lot faster.

With fix all you just need one click to add services to your monitoring

You have just successfully added a first host to the monitoring. You can add more hosts in the same way. Checkmk does not depend on its agents. When adding network devices you can follow most of these same steps as well. If you want to monitor network devices with SNMP for instance, you will need to customise that under 'Monitoring agents' after clicking on 'Add host', switching the default value to 'SNMP' and adding your SNMP details (SNMP version and credentials).

Checkmk will always ask for confirmation of changes made to the monitoring. This is a safety mechanism and it allows you to review any changes before they affect your monitoring. For this very small monitoring environment, this step does not look like a big deal, but you should keep in mind that Checkmk is often used to monitor distributed environments with many users. This way, a monitoring administrator always stays on top of things and can verify any change made to the monitoring. New hosts and other changes in the configuration initially have no effect on the monitoring, you need to activate these before they go into production.

In Checkmk, nothing goes in operation without activating the changes

The next steps for a happy monitoring

This tutorial covered the basics of working with Checkmk, but your real monitoring experience is only just starting here. Of course it is possible to simultaneously add multiple hosts to a monitoring in Checkmk. You may have noticed that Checkmk provides agents for almost all operating systems, so you can go ahead and add more hosts as required. The procedure is similar for other systems.

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