Hi! 
We are currently evaluating Rocket.Chat and are looking for a mission critical solution.
Ideally we are looking to deploy Rocket.Chat across multiple clusters to ensure it never goes down, is this supported?
Are there any officially supported or recommended designs for running Rocket.Chat with high availability across multiple Kubernetes clusters?
Only if you have a subscription plan.
It won’t work on CE.
Details in the docs.
(It is open source so you could take the code, remove any blocks, and build your own but a lot of extra functionality is in the EE repo)
Search “High Availability”
Microservices are needed if you scale.
From what I can tell the solution is only HA within a single cluster with no option to span it over multiple Kubernetes clusters.
I wouldn’t mind paying for an enterprise license to avoid having to make modifications to the source code as I am not a developer.
I cannot tell if it’s a limitation in Rocket.Chat or if it is possible to deploy it outside of the Helm chart which will support this architecture.
The whole scaleable HA/Cluster thing is a “Premium” feature.
If you speak to sales they’ll explain it all.
But it is not something you can do “for free”.