Environment
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Checkmk Edition: Enterprise Edition (CEE)
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Appliance Version: virt1 Mark I 1.7.2
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Checkmk Version: 2.4.0p24 (latest available from official downloads)
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vCenter Version: VMware vCenter Server 8.x
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Monitoring Method: vSphere Web Services API (SOAP)
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Monitoring User:
checkmk@vsphere.local -
Permissions: Read-Only, Global Permissions, Propagate enabled
Problem Summary
When Checkmk connects to vCenter 8.x using the built‑in VMware Special Agent (SOAP API):
ESXi hosts are discovered normally
Datastores are discovered normally
VM object appears, but only “Power State” is shown
All VM performance metrics (CPU, memory, disk I/O, network I/O) are missing
No piggyback data is generated for VMs
VM inventory does not appear in special agent output
The Checkmk service output always contains:
[piggyback] Success (but no data found for this host)
This issue affects all VMs under the monitored vCenter.
Detailed Symptoms
For every VM (example: test-rhfs2) Checkmk shows ONLY:
- Power State → OK
power state: poweredOn
But these checks are missing for all VMs:
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CPU usage
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Memory usage
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Balloon / swapping
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Disk latency / IOPS
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Network throughput
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Guest Tools state
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VM hardware
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VM configuration
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Snapshot age
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etc.
This means:
Only the very top-level VM summary is detected; none of the actual VM performance counters are processed.
What We Confirmed (This is NOT a permissions problem)
1. Permissions verified through vSphere GUI
The monitoring user has Global Read-Only, propagate to children, and can see all VMs.
2. Verified using govc (VMware REST/WS client)
Using the same read‑only credentials:
govc vm.info /DC/vm/test-rhfs2
govc returns full VM information:
Name: test-rhfs2
Guest name: RHEL8
CPU: 16 vCPU
Memory: 16384MB
Power state: poweredOn
Host: test-vmprod04.wrs.com
So the vCenter API is working correctly, and the user has full VM visibility.
3. Network connectivity from Checkmk server to vCenter: OK
4. SOAP special agent output = NO VirtualMachine objects
Only HostSystem objects appear.
Community Evidence Suggesting SOAP Agent Bug in Checkmk 2.4.x
We found the following public report that matches our exact symptoms:
“Most vSphere ESX plugins do not handle the info on version 2.4.0p12 … piggyback has no data … VM data missing.”
Source: Checkmk Community Forum
Most Vsphere ESX plugins do not handle the info on version 2.4.0p12
This report describes the same behaviors:
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ESXi OK
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Datastores OK
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VM metrics missing
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SOAP agent fails to parse VM counters
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piggyback empty
Even though the report is for 2.4.0p12, our version 2.4.0p24 shows the exact same symptoms.
Expected Behavior
Checkmk should:
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Retrieve VM list
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Generate piggyback folders for each VM
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Populate CPU, memory, disk, and network performance metrics
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Display VMware guest checks (tools, snapshots, hardware, etc.)
Actual Behavior
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VM list not returned by the Checkmk SOAP agent
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Only PowerState appears
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No performance data returned
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No piggyback VM folders created
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Agent output includes no
<virtualmachine>sections
Conclusion
Based on:
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Valid vSphere API responses (verified via govc)
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Correct user permissions
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Correct network connectivity
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SOAP agent output missing VM objects
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Matching community reports for Checkmk 2.4.x
This strongly suggests a SOAP compatibility issue / parsing bug in Checkmk 2.4.x VMware special agent when communicating with vCenter 8.x.
Request (for Checkmk Support / Developers)
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Please confirm if there is a known issue in 2.4.x with vCenter 8.x SOAP API.
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Is there a hotfix or workaround available?
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Is there an upcoming REST‑based VMware agent or new special agent planned?
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If available, can we join any preview/testing program for vSphere REST monitoring?