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This article discusses known issues that affect custom kubelet configurations on Microsoft Windows nodes in the Azure Kubernetes Service (AKS). For more information about this feature, see Customize node configuration for AKS node pools.
Log sizes exceed the specified maximum during aggressive log writing
On a Windows virtual machine (VM), log sizes grow beyond the value of the container-log-max-size setting if a container is writing to the log aggressively. During heavy log writing periods, the log file grows too quickly for log rotation to occur before the container-log-max-size setting limit is exceeded.
If several pods are aggressively writing to the log, the log size can grow to dozens of gibibytes (GiBs) before the log is rotated (compressed and replaced), even if the maximum size is only in the dozens of mebibytes (MiBs).
For more information, see Kubernetes GitHub issue 110630, "Kubelet does not respect container-log-max-size on time, during heavy log writes from container."
Affected versions
The excessive log size issue applies to all versions of Kubernetes.
Kubelet log file compression fails
On a Windows VM, when the kubelet tries to compress a log file into a .gz archive format, it stops responding during the final step of the process (trying to rename the archive before it closes the file).
For more information, see Kubernetes GitHub issue 111548, "Kubelet log compression fails on Windows."
Affected versions
The kubelet log file compression issue applies to all versions of Kubernetes that are older than version 1.23. It applies also to certain early versions of Kubernetes 1.23 and 1.24, as shown in the following table. The log file compression issue is fixed for Kubernetes version 1.25.0 (in Kubernetes GitHub pull request 111549) and all subsequent versions of Kubernetes.
| Kubernetes x.y version | Versions that the known issue applies to | GitHub fix pull request number on Kubernetes |
|---|---|---|
1.24 |
All versions before 1.24.7 |
112482 |
1.23 |
All versions before 1.23.13 |
112483 |
For more information, see the January 29, 2023 release of the AKS changelog.
Custom OS configurations fail
Symptoms
A custom OS configuration doesn't get applied.
Cause
This issue occurs if you try to apply the custom OS configuration on a Windows node pool. Currently, OS configurations aren't supported on Windows node pools. These configurations work only on Linux node pools.
Workaround
Apply the custom OS configuration at the cluster level or node pool level for a Linux node pool. To check whether the custom node configuration is in use, see Confirm settings have been applied.
Contact us for help
If you have questions or need help, create a support request, or ask Azure community support. You can also submit product feedback to Azure feedback community.