Werk #19457: Docker container disk IO: service goes UNKNOWN when all counters are zero
| Component | Checks & agents | ||||||
| Title | Docker container disk IO: service goes UNKNOWN when all counters are zero | ||||||
| Date | Mar 15, 2026 | ||||||
| Level | Trivial Change | ||||||
| Class | Bug Fix | ||||||
| Compatibility | Compatible - no manual interaction needed | ||||||
| Checkmk versions & editions |
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The Docker container disk IO service could go UNKNOWN when io_service_bytes_recursive reported zero for both read and write, such as on containers with no disk activity. In this case, the parser filtered out all devices with zero counters, returning an empty section instead of NoIOSection. This caused the check plugin to find no matching item and produce no result, leading to the service status becoming UNKNOWN.
The parser now returns NoIOSection when all devices have zero counters. This causes the check to raise IgnoreResultsError, which keeps the service in its previous OK state instead of changing to UNKNOWN.
Previously, Docker container disk IO services could unexpectedly show an UNKNOWN status when there was no disk activity, causing confusion. With this fix, the service status remains OK in such cases, avoiding false alerts. No user action is required.