This page documents the list of known issues in Kubermatic KubeOne along with
possible workarounds and recommendations.
This list applies to KubeOne 1.7 releases. For KubeOne 1.6, please consider
the v1.6 version of this document. For earlier releases,
please consult the appropriate changelog.
Cilium CNI is not working on clusters running CentOS 7
Cilium CNI is not supported on CentOS 7 because it’s using too older kernel
version which is not supported by Cilium itself. For more details, consider
the official Cilium documentation.
Please consider using an operating system with a newer kernel version, such
as Ubuntu, Rocky Linux, and Flatcar. See
the official Cilium documentation for a list of
operating systems and versions supported by Cilium.
Internal Kubernetes endpoints unreachable on vSphere with Cilium/Canal
- Unable to perform CRUD operations on resources governed by webhooks (e.g. ValidatingWebhookConfiguration, MutatingWebhookConfiguration, etc.). The following error is observed:
Internal error occurred: failed calling webhook "webhook-name": failed to call webhook: Post "https://webhook-service-name.namespace.svc:443/webhook-endpoint": context deadline exceeded
- Unable to reach internal Kubernetes endpoints from pods/nodes.
- ICMP is working but TCP/UDP is not.
On recent enough VMware hardware compatibility version (i.e >= 15 or maybe >= 14), CNI connectivity breaks because of hardware segmentation offload.
cilium-health status has ICMP connectivity working, but not TCP connectivity. cilium-health status may also fail completely.
sudo ethtool -K ens192 tx-udp_tnl-segmentation off
sudo ethtool -K ens192 tx-udp_tnl-csum-segmentation off
These flags are related to the hardware segmentation offload done by the vSphere driver VMXNET3. We have observed this issue for both Cilium and Canal CNI running on Ubuntu 22.04.
We have two options to configure these flags for KubeOne installations: