Is Serf an added value when a container orchestration platform like kubernetes is used?
Serf is gossip protocol implementation and has absolutely nothing to do with orchestration tools like k8s. Even if such protocol is used internally, then in most cases it isn't available for you applications running in given orchestrator.

So if your app or workflow depends on gossip protocol, then you will have use out of Serf, otherwise there is no point.



Gossip protocol is way of messaging to all nodes without:


Centralized point of knowledge
Single point of failure
Using whole network capability of any of the nodes


In simple words it works like "message chains" ("If you do not send this to N people you will never find your love" or something like that).


One node send notification to N out of M of its fellows
If you receive message that you have already received, then do nothing.
Otherwise go to step 1.


Given such simple protocol you can calculate probability when all your nodes will receive message with 99% chance.