Werk #22017: Relation detection: Find the relations between your hosts
| Component | Setup | ||
| Title | Relation detection: Find the relations between your hosts | ||
| Date | Sep 18, 2026 | ||
| Level | Trivial Change | ||
| Class | New Feature | ||
| Compatibility | Compatible - no manual interaction needed | ||
| Checkmk versions & editions |
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The new Setup page "Relation detection" finds hosts that belong together and proposes them as relations (see werk #20059), for all your hosts at once. For now, it finds management boards and their OS hosts. It works like the service discovery: Checkmk proposes, you decide, and nothing is changed until you store.
Checkmk can find a relation in two ways:
- In the host names: srv-01-ilo next to srv-01 means srv-01-ilo is the management board of srv-01.
- In host labels and custom host attributes: srv-01 and its board carry the same value, such as a serial number your CMDB writes into a host label.
Where to find it
Setup > Hosts, menu "Related" > "Relation detection". You need the permissions "Make changes, perform actions", "Host management" and "Modify existing hosts". The page reads the hosts in all folders you may see.
How it works
The page takes you through four steps.
1. Relation mapping
Under "Relation indicators", choose where Checkmk looks: "Host names" (the default), "Host labels and custom host attributes", or both.
Under "Folder", and "Site" in a distributed setup, you can restrict the search. It starts with the folder you opened the page from, subfolders included. A relation is found if at least one of its two hosts is in there, so boards kept in a folder of their own are found as well.
2. Relation proposal
Checkmk lists what it found, with examples from your hosts. Tick what you want to use.
"In the host names" lists words that make one host name out of another, such as "ilo" in srv-01-ilo. The host with the word is the management board.
- The usual vendor words (ilo, idrac, bmc, ipmi and others) are ticked already.
- Other words are listed under "Other words your host names use". They are only used if you tick them.
"In host labels and custom host attributes" lists labels and attributes whose values are each shared by only a few hosts, like a serial number. When you tick one, the page shows how Checkmk tells the board apart from the other hosts of a group. With "Tell them apart another way" you can choose instead:
- the host with a vendor word in its name,
- the host with a certain host label or custom host attribute value, for example "cmdb/kind: board", or
- "I will pick it in the next step, one group at a time".
Only labels set in Setup are read, on the host or its folders. Labels from host label rules and labels found by the service discovery are not used.
If something is missing, add it under "Additional indicators": "A word in host names" or "A value hosts share".
3. Relation review
For each finding, the page shows how many relations are "New", "Already related", "Related in another way", "Cannot be stored" or "Needs your answer", with a few examples. Every finding you tick is stored as a whole. To leave something out:
- untick the whole finding, or
- click "Show all … relations", search or filter, and untick single relations, or all matching ones with "Untick all of them".
A relation that cannot be stored says why.
Two things may need your decision:
- Conflicts: two findings disagree about the same two hosts. For example, the name says one is the board and the CMDB label says the other. Nothing is stored for these two hosts until you pick one.
- Questions: some hosts share a value, but nothing says which of them is the board. Pick the board for each group, and it is related to all other hosts of the group. This also covers a board with all the blades of a chassis.
A relation that already exists is never replaced, however it was entered. If it says something else, the pair is shown as "Related in another way".
4. Summary
Check what is about to be stored and click "Store … relations". The relations are stored in the background. The result shows what came of each finding. Anything that could not be stored is listed under "What could not be stored", with the reason: fix it in the properties of the host or its folder, and scan again.
Each changed host gets a pending change. Click "Activate changes" to bring the relations into the monitoring. They are ordinary relations, stored on both hosts, and you can edit them in the host properties later.