Check_MK returns (null) on ping-only hosts

Troubleshooting
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1

CMK version: Checkmk Raw Edition 2.1.0
OS version: Debian 11

Error message: We have over 30 hosts that are simply checked via ping to see if they are online or not. In version 2.0.0, this also works without any problems. Since today’s update to version 2.1.0, the service “Check_MK” is set to CRIT for all these hosts and the summary only says “(null)”.

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Output of “cmk --debug -vvn hostname”: Hastebin: Send and Save Text or Code Snippets for Free | Toptal®

2

This is due to the changed scope of the service Check_MK. You might just remove this service from monitoring. I’ll hint the developers on the missing summary.

Deep link to the section explaining the changes in the update article:

3

Thank you for your answer. Unfortunately, disabling the service doesn’t work. I’ve created a rule for it 15 minutes ago, but they are still on Crit.

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4

The scope may have changed, but a ping-only host should still be possible without much hassle.

5

What’s your setting for agent integration? Monitoring agents > Checkmk agent / API integrations This should be set to “no no”.

6

Yes, that solved it! It was set to “Configured API integrations, no Checkmk agent”. Thank you

7

Glad it’s solved!
FYI: This quirk was caused by the fact that we changed the condition to show the “Check_MK” service. It used to be “if there are passive services”, but it now is “if there are configured data sources”.
See Add Check_MK service for hosts without passive services.

8

We’ll update the documentation. This might also have implications on the article explaining datasource programs.