1. Why Linux?
Checkmk is a comprehensive software package, which basically requires Linux as its operating system. Why? Linux is an excellent platform for the operation of Checkmk, because it is very performant and stable, and many important tools are already integrated. Alongside this there is the pleasant side benefit of the availability of completely-free distributions of Linux with Debian, Ubuntu, AlmaLinux and Rocky Linux, which are enterprise-capable and supported by Checkmk.
If you do not want to deal with Linux under any circumstances, it is also possible to run Checkmk as a virtual appliance, a physical appliance, or as a Docker-Container.
2. Supported Distributions
Linux is a free system and offered by many producers in their own variants (distributions). This is of course very positive, because competition stimulates business, increases quality, and as a user you always have the possibility to switch to a Linux distribution that is better-suited to your needs.
However, this diversity also has a disadvantage: The available distributions differ in many details, among other things also in the versions of the provided software libraries, directory paths, pre-configuration, etc.
To make sure that everything runs smoothly with Checkmk, we decided from the very beginning to develop a separate installation package of Checkmk for every important Linux distribution. The supported distributions are:
Red Hat Enterprise Linux (RHEL) and binary compatible derivatives (CentOS, AlmaLinux, Rocky Linux, Oracle Linux…)
SUSE Linux Enterprise Server (SLES)
Debian
Ubuntu as LTS versions
Generally we support any LTS (long term support) version of the mentioned Linux distributions that was in active security maintenance at release time of a certain version of Checkmk. This means there might be packages provided for distributions that are not of support or in extended support (with costs). Exact version numbers of supported distributions are listed in our compatibility matrix, on the same page you can also read about our OS Support Policy.
For the installation of Checkmk you need a physical or virtual server on which you have already installed Linux. The installation is then achieved in four steps:
Preparing the Linux-System
Setting-up the package sources
Downloading of the appropriate Checkmk package
Installation of the Checkmk package
3. Preparation of the Linux system
Depending on which distribution you are installing, different steps are necessary for the preparation. For this reason we will assume that the Linux system on which the Checkmk is to be installed has been installed with the manufacturer’s default settings, and correctly-connected to the network, so that it is accessible via HTTP and SSH from your workplace.
3.1. Partitioning hard drive space
Checkmk stores its data under the /opt/omd physical path, to be precise /opt/omd/versions for the Checkmk Software and /opt/omd/sites for monitoring data.
If the system is to be used exclusively for Checkmk, the major part of the hard drive’s free space should be available.
In this case it is not essential — but very desirable — that /opt/omd, or /opt has its own partition.
3.2. SMTP for outgoing emails
If you wish to send monitoring notifications by email, then for outgoing emails a correct configuration of the SMTP service is required.
To achieve this, an SMTP without local delivery such as nullmailer, msmtp or esmtp can be configured.
Usually here you define a smarthost to which all emails are to be redirected.
3.3. Settings for the system time
In order for the monitoring server to have a correct system time, we strongly recommend setting up NTP. The hardware clock should be set to UTC. As soon as the server is taken into monitoring with Checkmk, NTP will ensure the correct time is used for all functions.
4. Installation instructions
Depending on the Linux distribution you want to install Checkmk onto, please follow one of the dedicated installation instruction below: