If you experience that the Checkmk agent is failing on CentOS 7 with systemd like so:
systemctl list-units | grep check-mk ... check-mk-agent@99995-<ipofhost>:6556-<ipofcheckmkserver>56520.service loaded failed failed Checkmk agent (<ipofcheckmkserver>56520) check-mk-agent@99997-<ipofhost>:6556-<ipofcheckmkserver>57602.service loaded failed failed Checkmk agent (<ipofcheckmkserver>57602) check-mk-agent@99999-<ipofhost>:6556-<ipofcheckmkserver>58616.service loaded failed failed Checkmk agent (<ipofcheckmkserver>58616) check-mk-agent.socket
systemctl status check-mk-agent@99999-<ipofhost>:6556-<ipofcheckmkserver>58616.service check-mk-agent@99999-<ipofhost>:6556-<ipofcheckmkserver>58616.service - Checkmk agent (<ipofcheckmkserver>58616) Loaded: loaded (/etc/systemd/system/check-mk-agent@.service; static; vendor preset: disabled) Active: failed (Result: resources) since Fri 2021-11-19 23:24:49 UTC; 3 weeks 3 days ago Process: 23951 ExecStart=/usr/bin/check_mk_agent (code=exited, status=0/SUCCESS) Main PID: 23951 (code=exited, status=0/SUCCESS)
Nov 19 23:24:48 <hostname> systemd[1]: Starting Checkmk agent (<ipofcheckmkserver>58616)... Nov 19 23:24:49 <hostname> systemd[1]: check-mk-agent@99999-<ipofhost>:6556-<ipofcheckmkserver>58616.service failed to run 'stop-post' task: Transport endpoint is not connected Nov 19 23:24:49 <hostname> systemd[1]: Failed to start Checkmk agent (<ipofcheckmkserver>58616). Nov 19 23:24:49 <hostname> systemd[1]: Unit check-mk-agent@99999-<ipofhost>:6556-<ipofcheckmkserver>58616.service entered failed state. Nov 19 23:24:49 <hostname>systemd[1]: check-mk-agent@99999-<ipofhost>:6556-<ipofcheckmkserver>58616.service failed.
Then there are two options you can get this working:
- Switch to xinetd or SSH
- Upgrade to CentOS 8 or a suitable (preferably binary compatible) alternative (e.g., Rocky Linux or AlmaLinux)
The root cause for this is that CentOS 7 might use an old systemd version. Checkmk requires systemd >=235.
You can check your systemd version with systemctl --version
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