Setting up Checkmk

Before you begin installing Checkmk, you must first decide which of the four available editions you want to use:

The Checkmk Raw Edition (CRE) is free, 100 % Open Source and incorporates Nagios as its core. You can use it to comprehensively monitor complex environments. Support is available in our Forum from the Checkmk community.

The Checkmk Enterprise Free Edition (CFE) is the right one for you if you want to test the Standard Edition without obligation or if you want to use Checkmk on a small scale with one site with up to 25 monitored hosts. The Free Edition contains all the features of the Standard Edition, is free of charge and unlimited for the first 30 days. Both the Free Edition and the Raw Edition can be upgraded directly to the Standard Edition later without any extra complications.

The Checkmk Enterprise Standard Edition (CEE) is primarily aimed at professional users and offers a number of interesting features beyond the scope of the Raw Edition, such as the Checkmk Micro Core (CMC) with its own very high-performance core which replaces Nagios, a flexible distribution of Checkmk monitoring agents (which obtain information from the monitored target systems), a large number of sophisticated dashlets to build into dashboards, reporting, and much more. For the Standard Edition you can optionally receive professional support from us or from one of our partners.

The Checkmk Enterprise Managed Services Edition (CME) is a multi-client-capable extension of the Standard Edition which, via distributed monitoring, has all the necessary functions for operating an individual Checkmk site for each one of multiple independent customers. If you want to provide these services for your customers, this is your edition. More detailed information on the concept of managed services can be found in the introduction to this article.

You can find a breakdown of the differences between the editions on our homepage.

Whenever in this User guide we discuss functions that apply only to one of the Enterprise Editions — i.e. the CFE, CEE or CME — we indicate this with the symbol as in this paragraph.

We are continually developing all editions of Checkmk and therefore there are different versions of each edition. To get started, we generally recommend the latest stable version. A detailed overview of what other versions are available can be found in this article.

The Checkmk server fundamentally requires a Linux system on which it can run. (Of course, you can still monitor Windows and other operating systems). If you do not want to set up your own Linux server, you can also run Checkmk using Docker or an appliance. There are four options in total, which we briefly present below and which are installed in different ways. When you have finished installing your variant, continue reading in the next chapter, which is about creating a site.

Checkmk has a special feature that may seem unimportant at first, but it is one which has proven very useful in practice — you can run several independent sites of Checkmk in parallel on the same server. Each site can even run a different version of Checkmk.

Here are two common uses for this well-thought-out feature:

If you have just installed Checkmk on a Linux server, there will be no sites as yet. In this chapter we will show you how to create a site following an installation of Checkmk software on a Linux distribution.

Note: Checkmk appliances are administered via a web GUI that also covers the creation of sites. This is explained in the article on the appliance. If you are running Checkmk in a Docker container, a site will be created for you automatically during its installation.

First choose a name for your site. This may only consist of letters and numbers. The convention here is lower case letters. In the User guide, we use the name mysite in examples. Replace this name with your own site name.

The creation itself is very simple. As root, simply enter the command omd create followed by the name for the site:

When creating a new site, the following events take place:

By the way — whenever we give file path names in the User guide that do not begin with a slash, they refer to the site directory. If you are in this directory, you can therefore use such paths directly in this way. This also applies, for example, to the file etc/htpasswd, whose absolute path here is /omd/sites/mysite/etc/htpasswd. This file contains the passwords for the Checkmk users of this site. Do not confuse this file with /etc/htpasswd.

Note: If you receive this or a similar error message when trying to create the site:

then a Linux user or group already exists with the site name you specified. In such a case, simply choose a different name.

Once you have created the new site, subsequent administration is no longer carried out as the root, but instead as the site user. The easiest way to become a site user is with the following command:

You can see from the changed prompt that you are now logged into the site, and as the command pwd shows, you will then be automatically in the site directory:

As you have seen in the output from omd create, an administrative Checkmk user named cmkadmin is automatically created when the site is created. This user is for logging into the web interface in Checkmk and has been given a random password. As the site user, you can easily change this password:

A site can be started or stopped. The start type is automatic, which means that a started site is also restarted after a reboot of the computer. Newly-created sites nevertheless begin their lives in a stopped state. You can easily check this with the command omd status, which shows the status of all the individual processes that are necessary to operate the site:

With a simple omd start you can start the site:

As expected, afterwards the status shows all services as running:

Since the Enterprise Editions have more features than the Raw Edition, you will see more services there. In addition, you will find cmc as the core instead of nagios:

The omd command provides many more options for controlling and configuring sites, and these are described in the article on sites. In addition, you can find out how the directory structure for Checkmk is set up in the article on Checkmk in the command line.

With the site running, you can now proceed. Each site has its own URL that you can open in your browser. This URL consists of the name or IP address of the Checkmk server, a slash, and the name of the site, e.g. http://mycmkserver/mysite. You will find this login dialog at this address:

Now log in with the user name cmkadmin and the password you chose or changed at the beginning. This will take you to the start page in Checkmk, which we will look at in more detail in the next chapter.

If your site has not started, you will see the following error message instead of the login dialog:

If there is no site with this name at all — or you have landed on a server without Checkmk — it will look more like this:

Important: As soon as you are running Checkmk as production system, we recommend that for security reasons you only allow access to the interface in a secured manner. You can find out what you need to do for this in the article on securing the web interface with HTTPS.

Continue with the Checkmk user interface