checkmk_agent

An Ansible Role to install the agent/client for CheckMK RAW edition.

This is a complete rebuild of the install-check_mk-agent role I created and maintained for years, undertaken due to changes in CI/CD and naming conventions in Ansible Galaxy & CheckMK.

All tasks are tagged with checkmk-agent.

The following distributions have been tested automatically:

• Debian 10 "Buster"
• Debian 11 "Bullseye"
• Debian 12 "Bookworm"
• Fedora 38
• Fedora 39
• Fedora 40
• Microsoft Windows Server 2019 / Microsoft Windows 10
• Microsoft Windows Server 2022 / Microsoft Windows 11
• Ubuntu 20.04 LTS "Focal Fossa"
• Ubuntu 22.04 LTS "Jammy Jellyfish"
• Ubuntu 24.04 LTS "Noble Numbat"

For performance reasons, the following "sections" have been disabled by default in the Windows agent:

• services
• msexch
• dotnet_clrmemory
• wmi_webservices
• wmi_cpuload
• ps
• fileinfo
• logwatch
• openhardwaremonitor

In addition, the execution of plugins have been adjusted:

• Timeout raised from 30 to 120
• Async enabled
• Cache_age set to 3600 (1 hour)

Create your own "check_mk.user.yml.j2" and override checkmk_agent_win_config_src to customize further, or set the checkmk_agent_win_config_optimize variable to false to disable this optimization.

Similar modifications have been made to the docker.cfg default file. Here, all docker sections have been enabled and can be returned to the default by setting the checkmk_agent_docker_complete variable to false.

Recent Version Matrix

CheckMK Raw Edition Version	Role Version/Tag
2.3.0p21	1.1.10
2.3.0p20	1.1.9
2.3.0p19	1.1.8
2.3.0p18	1.1.7
2.3.0p17	1.1.5 - 1.1.6

Requirements

This role requires no other roles. It is designed to be compatible with CheckMK server in general and kso512.checkmk_server specifically.

If connecting to a Windows host with Windows Remote Management (WinRM), you may need to install the pywinrm package on your Ansible system:

pip install "pywinrm>=0.3.0"

This role utilizes SSH on Unix-type systems instead of the default port 6556. This encrypts communications and avoids opening a new port for monitoring and setting up a new service.

To create authentication keys for SSH, use the "ssh-keygen" program as shown here.

Example to create default keys with no passphrase in the local folder:

ssh-keygen -C "cmkagent@$HOSTNAME" -f ./id_rsa -N "" -v

This will create two files: id_rsa & id_rsa.pub

id_rsa = Private key which should be kept safe. This file needs to be placed in the ~/.ssh folder of the live CheckMK Agent user. Example using the "kso512.checkmk_server" default user & site:

cp ./id_rsa /opt/omd/sites/test/.ssh

id_rsa.pub = Public key which may be shared with other trusted hosts. This file needs to be added to your own local "authorized_keys.j2" file. Assuming a default role structure:

echo '# {{ ansible_managed }}' > /etc/ansible/local/authorized_keys.j2
cat ./id_rsa.pub >> /etc/ansible/local/authorized_keys.j2

Then declare local/authorized_keys.j2 as checkmk_agent_authkey_src in your own variables; an example is shown below.

Finally, configure CheckMK itself to leverage these files instead of trying to connect to TCP port 6556:

• Log in to CheckMK
• Setup > Search > "individual" > Individual program call instead of agent access
• Create rule in folder: Main directory
  • Description: Use SSH and cmkagent account with SSH keys
  • Command line to execute: ssh -i ~/.ssh/id_rsa -l cmkagent <IP> sudo /home/cmkagent/check_mk_agent
  • Explicit hosts: (select a test host, then once it's working, set up host tags or labels)
  • Save
• 1 change > Activate on selected sites

Role Variables

Some of these may be seem redundant but are specified so future users can override them with local variables as needed.

Table of Variables (with Defaults)

Variable	Description	Default
checkmk_agent_authkey_dest	Full pathname of "authorized_keys" file	"{{ checkmk_agent_ssh_path }}/authorized_keys"
checkmk_agent_authkey_group	Name of the group that should own the "authorized_keys" file	"{{ checkmk_agent_ssh_group }}"
checkmk_agent_authkey_mode	File mode settings of the "authorized_keys" file	"0600"
checkmk_agent_authkey_src	Filename of the "authorized_keys" template	authorized_keys.j2
checkmk_agent_authkey_user	Name of the user that should own the "authorized_keys" file	"{{ checkmk_agent_ssh_user }}"
checkmk_agent_cache_group	Name of the group that should own the "cache" folder and files	"{{ checkmk_agent_cache_user }}"
checkmk_agent_cache_mode	File mode settings of the "cache" folder and files	"{{ checkmk_agent_mode }}"
checkmk_agent_cache_path	Full pathname of "cache" folder	"{{ checkmk_agent_home }}/cache"
checkmk_agent_cache_user	Name of the user that should own the "cache" folder and files	"{{ checkmk_agent_user }}"
checkmk_agent_comment	Full name of the CheckMK Agent user	CheckMK Agent
checkmk_agent_count_users_crit	Logged in users, critical threshold	15
checkmk_agent_count_users_warn	Logged in users, warning threshold	10
checkmk_agent_count_zombie_procs_crit	Zombie processes, critical threshold	10
checkmk_agent_count_zombie_procs_warn	Zombie processes, warning threshold	5
checkmk_agent_dest	Full pathname of the CheckMK Agent executable file	"{{ checkmk_agent_home }}/check_mk_agent"
checkmk_agent_docker_complete	Include all docker modules	true
checkmk_agent_docker_dest	Full pathname of the Docker configuration file	"{{ checkmk_agent_home }}/docker.cfg"
checkmk_agent_docker_group	Name of the group that should own the Docker configuration file	"{{ checkmk_agent_group }}"
checkmk_agent_docker_mode	File mode settings of the Docker configuration file	"0644"
checkmk_agent_docker_src	Filename of the Docker configuration file template	docker.cfg.j2
checkmk_agent_docker_user	Filename of the Docker configuration file template	"{{ checkmk_agent_user }}"
checkmk_agent_group	Name of the group that should own the CheckMK Agent executable file	"{{ checkmk_agent_user }}"
checkmk_agent_home	Full pathname of the CheckMK Agent user home folder	/home/{{ checkmk_agent_user }}
checkmk_agent_local_checks	List of checks to copy to the "local" folder	count_users count_zombie_procs
checkmk_agent_local_checks_async	List of checks to copy to the "local" async folders	(See NOTE A below)
checkmk_agent_local_group	Name of the group that should own the "local" folder and files	"{{ checkmk_agent_local_user }}"
checkmk_agent_local_mode	File mode settings of the "local" folder and files	"{{ checkmk_agent_mode }}"
checkmk_agent_local_path	Full pathname of "local" folder	"{{ checkmk_agent_home }}/local"
checkmk_agent_local_purge	Delete "local" folder before sync	false
checkmk_agent_local_user	Name of the user that should own the "local" folder and files	"{{ checkmk_agent_user }}"
checkmk_agent_mode	File mode settings of the CheckMK Agent executable file	"0755"
checkmk_agent_plugin_checks	List of checks to copy to the "plugin" folder	hpsa lvm mk_inventory.linux mk_iptables mk_nfsiostat mk_sshd_config netstat.linux nfsexports smart
checkmk_agent_plugin_checks_async	List of checks to copy to the "plugin" async folders	(See NOTE A below)
checkmk_agent_plugin_group	Name of the group that should own the "plugin" folder and files	"{{ checkmk_agent_plugin_user }}"
checkmk_agent_plugin_mode	File mode settings of the "plugin" folder and files	"{{ checkmk_agent_mode }}"
checkmk_agent_plugin_path	Full pathname of "plugin" folder	"{{ checkmk_agent_home }}/plugins"
checkmk_agent_plugin_purge	Delete "plugin" folder before sync	false
checkmk_agent_plugin_user	Name of the user that should own the "plugin" folder and files	"{{ checkmk_agent_user }}"
checkmk_agent_prereqs	List of packages needed for a successful installation	python3-docker sudo
checkmk_agent_prereqs_yum	List of packages needed for a successful installation with systems using YUM as their package manager	sudo
checkmk_agent_src	Filename of the CheckMK Agent executable file template	check_mk_agent.linux.j2
checkmk_agent_ssh_group	Name of the group that should own the ".ssh" folder and files	"{{ checkmk_agent_group }}"
checkmk_agent_ssh_mode	File mode settings of the ".ssh" folder and files	"0700"
checkmk_agent_ssh_path	Full pathname of ".ssh" folder	"{{ checkmk_agent_home }}/.ssh"
checkmk_agent_ssh_user	Name of the user that should own the ".ssh" folder and files	"{{ checkmk_agent_user }}"
checkmk_agent_spool_group	Name of the group that should own the "spool" folder and files	"{{ checkmk_agent_spool_user }}"
checkmk_agent_spool_mode	File mode settings of the "spool" folder and files	"{{ checkmk_agent_mode }}"
checkmk_agent_spool_path	Full pathname of "spool" folder	"{{ checkmk_agent_home }}/spool"
checkmk_agent_spool_user	Name of the user that should own the "spool" folder and files	"{{ checkmk_agent_user }}"
checkmk_agent_sudo_dest	Full pathname of "sudoers.d" file, used to grant the CheckMK Agent user sudo access to the CheckMK Agent executable file	/etc/sudoers.d/99_cmkagent
checkmk_agent_sudo_group	Name of the group that should own the "sudoers.d" file	"{{ checkmk_agent_sudo_owner }}"
checkmk_agent_sudo_mode	File mode settings of the "sudoers.d" file	"0440"
checkmk_agent_sudo_owner	Name of the user that should own the "sudoers.d" file	root
checkmk_agent_sudo_src	Filename of the "sudoers.d" file template	99_cmkagent.j2
checkmk_agent_sudo_validate	Command used to validate the "sudoers.d" file; %s will be filled in with checkmk_agent_sudo_dest	'visudo -cf %s'
checkmk_agent_user	Login name of the CheckMK Agent user	cmkagent
checkmk_agent_version	Version of CheckMK Agent to install	2.3.0p21
checkmk_agent_win_config_dest	Full pathname of configuration file	"{{ checkmk_agent_win_data_folder }}check_mk.user.yml"
checkmk_agent_win_config_optimize	Optimize the Windows agent by dropping some of the slower checks	true
checkmk_agent_win_config_src	Filename of the configuration file template	check_mk.user.yml.j2
checkmk_agent_win_data_folder	Full pathname of the CheckMK Agent data folder	C:\\ProgramData\\checkmk\\agent\\
checkmk_agent_win_install_dest	Full pathname of the CheckMK Agent installation file	c:\\Users\\{{ ansible_user }}\\Downloads\\{{ checkmk_agent_win_install_src }}
checkmk_agent_win_install_src	Short file name of the CheckMK Agent installation file	check_mk_agent.msi
checkmk_agent_win_plugins	List of Windows plugins to copy to the "plugin" folder"	mk_inventory.vbs windows_updates.vbs
checkmk_agent_win_productid	Version-specific "Product ID" to install	"{B6212139-D124-4782-8F81-05D08203092D}"

NOTE A

checkmk_agent_local_checks_async and checkmk_agent_plugin_checks_async - List of checks to copy to the "plugin" async folders. Per the documentation:

The output of local checks, like that of agent plug-ins, can be cached. This can be necessary if a script has a longer processing time. Such a script is then executed asynchronously and only in a defined time interval and the last output is cached. If the agent is queried again before the time expires, it uses this cache for the local check and returns it in the agent output.

The format of these lists is as follows, with checkmk_agent_plugin_checks_async shown:

300:
  - apache_status.py
600:
  - ""
900:
  - ""
1800:
  - ""
86400:
  - mk_apt
  - mk_docker.py

This runs the apache_status.py plugin only once per five minutes, and the mk_apt and mk_docker.py plugins only once per day, instead of every check. This shaves seconds off every remaining check of the day which uses the cached value.

Dependencies

None yet defined.

Example Playbook and Invocation

Example that uses a local authorized_keys file:

- hosts: all
  roles:
     - { role: kso512.checkmk_agent, checkmk_agent_authkey_src="local/authorized_keys.j2" }

Example that purges the plugin folder before re-creating it:

$ ansible-playbook site.yml -t checkmk-agent -e "checkmk_agent_plugin_purge=true"

...

TASK [kso512.checkmk_agent : Delete directory - plugins | FILE] ***********
changed: [instance]

TASK [kso512.checkmk_agent : Create directory - plugins | FILE] ***********
changed: [instance]

License

GNU General Public License version 2

Contributing

If you have any suggestions or ideas, please feel free to open an issue, or fork the repository and submit an merge request.

Author Information

• @kso512
• @iamdevnull