How to install Checkmk on Rocky Linux 9

In this Linux tutorial, you will learn how to install Checkmk on Rocky Linux 9 or other Red Hat based Linux distributions.

What is Checkmk?:

Checkmk is software developed in Python and C++ for IT Infrastructure monitoring. It is used for the monitoring of servers, applications, networks, cloud infrastructures (public, private, hybrid), containers, storage, databases and environment sensors.

Checkmk is available in three editions: an open source edition ("Checkmk Raw Edition – CRE"), a commercial enterprise edition ("Checkmk Enterprise Edition – CEE") and a commercial edition for managed services providers ("Checkmk Managed Services Edition – CME"). These Checkmk-Editions are available for a range of platforms, in particular for various versions of Debian, Ubuntu, SLES and Red Hat / CentOS, and also as a Docker Image. In addition, physical appliances of various sizes as well as a virtual appliance are offered to simplify the administration of the underlying operating system through a graphical user interface and to enable high-availability solutions.

The agents used by Checkmk to collect data are available for 11 platforms, including Windows. (Source: Wikipedia)

Environment Specification:

We are using a minimal Rocky Linux 9 virtual machine with following specifications.

CPU - 3.4 Ghz (2 cores)
Memory - 2 GB
Storage - 20 GB
Operating System - Rocky Linux release 9.1 (Blue Onyx)
Hostname – checkmk-01.centlinux.com
IP Address - 192.168.116.128/24

Prepare your Rocky Linux Server:

By using a ssh client, login to your Rocky linux server as root user.

If you are not used to Linux commandline then we recommend that you should attend online training Linux Command Line: From novice to wizard

Set a Hostname (preferably FQDN) and configure Local DNS Resolver by executing following commands at Linux terminal.

# hostnamectl set-hostname checkmk-01.centlinux.com
# echo "192.168.116.128 checkmk-01 checkmk-01.centlinux.com" >> /etc/hosts

Execute following command to update software packages in your Linux operating system.

# dnf update -y

If a software package related to Linux Kernel is updated by the above command, then you should reboot your Linux operating system with newly installed Kernel.

# reboot

After reboot, login as root user and check your Linux operating system and Kernel versions.

# cat /etc/rocky-release
Rocky Linux release 9.1 (Blue Onyx)

# uname -r
5.14.0-162.23.1.el9_1.x86_64

Install Third Party Yum Repositories:

Checkmk software requires some software package from EPEL (Extra Packages for Enterprise Linux) yum repository. Therefore, you need to install it by executing dnf command.

# dnf install -y epel-release

EPEL requires some packages from CRB (CodeReady Linux Builder) yum repository. Therefore, it will be better if you enable CRB yum repository too.

You can execute following command at Linux terminal to enable CRB yum repository.

# /usr/bin/crb enable
Enabling CRB repo
CRB repo is enabled and named: crb

Build your cache for newly installed yum repositories.

# dnf makecache

Configure SELinux and Linux Firewall:

Execute following Linux command to set SELinux boolean that allows your web server to access the network interfaces.

# setsebool -P httpd_can_network_connect 1

Allow the http service in Linux firewall.

# firewall-cmd --permanent --add-service=http
success

# firewall-cmd --reload
success

Installing Checkmk:

You can download different versions of this network monitoring software from Checkmk official website.

But we recommend that, you download RAW version of Checkmk if you do not have a license.

RAW version is open source edition and it is free to use under GNU GPL license.

Select your preferred Checkmk version, Platfrom and OS version. The same webpage will generate a Linux command according to your selection to download checkmk software.

Copy the command from Checkmk website to download the software straight from Linux terminal.

But you need to install wget command, because it is not preinstalled on minimal Rocky Linux 9 operating systems.

# dnf install -y wget

Now execute wget command to download Checkmk software.

# wget https://download.checkmk.com/checkmk/2.1.0p25/check-mk-raw-2.1.0p25-el9-38.x86_64.rpm
--2023-04-12 22:03:22--  https://download.checkmk.com/checkmk/2.1.0p25/check-mk-raw-2.1.0p25-el9-38.x86_64.rpm
Resolving download.checkmk.com (download.checkmk.com)... 45.133.11.29
Connecting to download.checkmk.com (download.checkmk.com)|45.133.11.29|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 167168936 (159M) [application/x-redhat-package-manager]
Saving to: ‘check-mk-raw-2.1.0p25-el9-38.x86_64.rpm’

check-mk-raw-2.1.0p 100%[===================>] 159.42M   439KB/s    in 7m 1s

2023-04-12 22:10:24 (388 KB/s) - ‘check-mk-raw-2.1.0p25-el9-38.x86_64.rpm’ saved [167168936/167168936]

You have already setup the required yum repositories, therefore, you can easily install checkmk software by executing following dnf command.

# dnf localinstall -y check-mk-raw-2.1.0p25-el9-38.x86_64.rpm

Verify installation of Checkmk software by querying it's version by using omd command.

# omd version
OMD - Open Monitoring Distribution Version 2.1.0p25.cre

Configure Checkmk Monitoring:

Create a new monitoring instance by using omd command.

# omd create monitoring
Adding /opt/omd/sites/monitoring/tmp to /etc/fstab.
Creating temporary filesystem /omd/sites/monitoring/tmp...OK
Updating core configuration...
Generating configuration for core (type nagios)...
Precompiling host checks...OK
Executing post-create script "01_create-sample-config.py"...OK
Restarting Apache...OK
Created new site monitoring with version 2.1.0p25.cre.

  The site can be started with omd start monitoring.
  The default web UI is available at http://checkmk-01.centlinux.com/monitoring/

  The admin user for the web applications is cmkadmin with password: rPOtCNpZ
  For command line administration of the site, log in with 'omd su monitoring'.
  After logging in, you can change the password for cmkadmin with 'cmk-passwd cmkadmin'.

Note down the URL of Checkmk Web UI and Password for chkadmin user.

Start the monitoring instance now.

# omd start monitoring
Temporary filesystem already mounted
Starting agent-receiver...OK
Starting mkeventd...OK
Starting rrdcached...OK
Starting npcd...OK
Starting nagios...OK
Starting apache...OK
Starting redis...OK
Initializing Crontab...OK

Change the Password of chkadmin user.

# omd su monitoring
OMD[monitoring]:~$ cmk-passwd cmkadmin
New password:
Re-type new password:
OMD[monitoring]:~$ exit
logout

Accessing Checkmk Web UI:

Open URL http://checkmk-01.centlinux.com/monitoring in a web browser.

You have reached at the Dashboard of Checkmk monitoring software.

Conclusion:

In this Linux tutorial, you have learned how to install Checkmk on Rocky Linux 9 or other Red Hat based Linux distributions.