While Selenium Hub is a single-point-of-failure, the recovery time of a failure is almost instant because Kubernetes will schedule a replacement container right away.
Sometimes removing a single-point-of-failure results in a more confusing and difficult to operate system. I didn't want to take on that risk.
In my situation, I had no need for HA (high availability) because the mean-time-to-recovery of a Selenium Hub is so fast and without any real consequence.
I think you should review your requirements to see if you really need a HA Hub.
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