To put it really simply: there's not a lot to kubernetes internals that you should know. The abstractions in k8s are really, really good.
The problem is migration. Old apps don't handle k8s very well. An application that follows the k8s model should be really easy to deal with. It either is one of a bunch of figuratively identical apps, and you connect randomly, or it is part of a master/Replica group. Older applications need help with that, or expect multiple connections to the same host, or... Any number of anti-patterns.
(Databases excluded - the Borg version of Statefulsets operates very differently, significantly because the trade-off of speed/reliability of persistent storage sucks in the cloud world right now.)
The problem is migration. Old apps don't handle k8s very well. An application that follows the k8s model should be really easy to deal with. It either is one of a bunch of figuratively identical apps, and you connect randomly, or it is part of a master/Replica group. Older applications need help with that, or expect multiple connections to the same host, or... Any number of anti-patterns.
(Databases excluded - the Borg version of Statefulsets operates very differently, significantly because the trade-off of speed/reliability of persistent storage sucks in the cloud world right now.)