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Checkmk is a very popular monitoring system that empowers administrators, managers, and DevOps teams to quickly identify issues that appear across their IT infrastructure. With Checkmk, you can closely monitor your inventory of servers and desktops for network traffic issues, CPU bottlenecks and even manage configurations. Checkmk is scalable, can monitor a vast array of services and works with most operating systems.

With a recent update, the developers of Checkmk have added Kubernetes support into the mix. If your business works with containerized applications and services, this might be a great time to deploy this helpful monitor to your systems.

I want to walk you through the process of installing the latest version of Checkmk to Ubuntu Server 22.04.

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What you’ll need

To install Checkmk so it can monitor Kubernetes, you’ll need a running instance of Ubuntu Server 22.04 with kubectl installed and a user with sudo privileges. That’s all: Let’s get to work.

How to install Checkmk

The first thing you’ll want to do is head to the Checkmk download page and make sure you’re downloading the latest version. As of this writing, that is 2.1.0, so we can download that with:

wget https://download.checkmk.com/checkmk/2.1.0p2/check-mk-free-2.1.0p2_0.jammy_amd64.deb

Once the file has downloaded, install it with:

sudo apt install ./check-mk-free-2.1.0p2_0.jammy_amd64.deb

The reason why we use apt instead of dpkg to install Checkmk is that there are dependencies to be added that dpkg won’t pick up. You can install with dpkg, but you’ll then have to fix the installation with:

sudo apt-get install -f

We avoid that with apt.

How to create a monitoring instance

With Checkmk installed, we then need to create our first monitoring instance. Let’s create the trtest instance with the command:

sudo omd create trtest

Once the instance has been created, start it with:

sudo omd start trtest

The output of the command will include the username and password you’ll use to access the web-based interface. Your monitoring instance has been created and can be accessed.

How to access the web-based GUI

With Checkmk installed and the trtest monitoring instance created, open a web browser and point it to http://SERVER/trtest where SERVER is the IP address of the hosting server and you should be presented with a login screen (Figure A).

Figure A

Image: Jack Wallen/TechRepublic. The Checkmk log-in window is ready for you to get to work.

The default username is cmkadmin, and the default password is generated after the installation. Log in and you should see the main Checkmk site.

Before you can do anything, however, you must install the agent on your server. You can install the agent to any host on your network and then add the host to Checkmk. I’ll demonstrate by installing the agent to the hosting server and then adding the hosting server for monitoring.

On the Checkmk main site, go to Setup | Agents | Windows, Linux, Solaris, AIX (Figure B).

Figure B

Image: Jack Wallen/TechRepublic. Accessing the agent download page in Checkmk.

In the resulting window, you’ll want to copy the URL for the Linux DEB file. Then, on the hosting server, issue the command:

wget http://LINK

Where LINK is the link you copied from Checkmk.

Once you’ve downloaded the installer to the hosting server, install it with the command:

sudo dpkg -i check-mk-agent-*.deb

How to add the host

Now that you’ve installed the agent, we need to add the host to Checkmk. For that, go to Setup | Hosts and then click Add Host.

In the resulting window (Figure C), type the hostname for the new host, and then click the checkbox for IPv4 Address and type the IP address for the host.

Figure C

Image: Jack Wallen/TechRepublic. Adding the new host to Checkmk.

Click Save & Go To Service configuration and then, in the resulting window, click Accept All (Figure D).

Figure D

Image: Jack Wallen/TechRepublic. Accepting all undecided services.

Finally, click the yellow stop sign at the top right corner and then click the red circle associated with the host (Figure E) to activate the changes.

Figure E

Image: Jack Wallen/TechRepublic. Acting the changes to our new host.

This action should take less than a minute. Once it completes, your host should then appear in the dashboard (Figure F).

Figure F

Image: Jack Wallen/TechRepublic. Our host is now visible to Checkmk.

And there you go, you’ve installed the latest version of Checkmk that allows you to monitor both a Docker Swarm and a Kubernetes cluster. If the hosting server is part of either, you should be able to monitor the nodes and containers from within the Checkmk web-based interface.

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