I wrote a Medium article on Hubble here
This example requires the GKE Dataplane V2 observability feature be enabled. Enabling this feature will provision an internal network load balancer.
UPDATE 2024-08-14: GKE DPv2 observability has gone through some updates since. So I'm just going to link the relevant Google Cloud docs to get setup with the CLI and UI:
There was a typo in the documentation for the advanced_datapath_observability_config setting so I made PR#8813 to correct.