Is way for GKE to support RHEL as worker node hostOS ?

[bdutta74]

Currently GKE seems to support Ubuntu or CoreOS based/derived host-OS for the worker nodes. It brings a unique challenge for some of the enterprise class SW containers that depend on RHEL8 UBI container baseOS images, since those baseOS images are "supported" (in the SLA backed support sense) by Red Hat, only if the worker-nodes are running RHEL8 OS. Is there any possibility or mechanism that while being on GKE (not self managed K8s on GCE), one could still use RHEL as worker node host OS ?

Thanks in advance.

[digil]

You are absolutely right. As of now, GKE offers these node image options per OS for your cluster. Currently, GKE doesn't have RHEL OS for its worker nodes which I believe you could report it as a feature request for 'Google Kubernetes Engine' service. 

That's being said, depending upon your workload pods requirement, you could always make use of 'Daemon Set' after it is being customized with the nodes of a Google Kubernetes Engine (GKE)
The process is called 'bootstrapping GKE nodes with DaemonSets' and this tutorial shows how to customize the nodes of a Google Kubernetes Engine (GKE) cluster by using DaemonSets & configMap. Theoretically, a Daemon set can be used to make any additional configuration changes(such as the file descriptor change or any other OS level changes that requires for your deployment/workload as in an RHEL environment) on GKE nodes every-time the node comes up. 

A few examples on how to use the Daemon set can be found in this articles(thread1, thread2) which I am providing you for a reference. 

[garisingh]

As you've found, GKE only supports using COS or Ubuntu as the OS on GKE-managed nodes.  We don't currently have any plans to add support for RHEL in the near future.

We of course do have customers using the UBI base image on GKE.  I can't really speak to Red Hat support and am by no mean a legal expert, but generally the issues with containers are not actually runtime platform dependent.  I imagine if you have an active RHEL subscription and have some issue with a UBI image, the problem would also occur on any platform and you'd likely get support from Red Hat.   But in terms of any runtime SLA, that would probably not be valid.