TIL: generation and resourceVersion answer different questions

Easy to mash these together when you’re staring at kubectl get -o yaml. They both go up. They mean different things.

metadata.resourceVersion is an opaque etcd/API concurrency token. Any write that changes the persisted object — spec, status, labels, finalizers, annotations — can bump it. You use it for optimistic concurrency (resourceVersion match on update) and for watches. Comparing two resourceVersion strings as numbers is a bad habit; treat them as opaque.

metadata.generation is specifically about desired state. The API server increments it when the spec (or other generation-tracked fields) change. Pure status updates from a controller typically leave generation alone. That’s why controllers can say ‘I reconciled generation N’ without caring about every noisy status write in between.

metadata:
  generation: 4
  resourceVersion: "184291"
status:
  observedGeneration: 4

If you’re deciding whether a controller has caught up to the user’s intent, look at generation / observedGeneration. If you’re doing a conditional update or debugging watch lag, look at resourceVersion.

Same cluster, two clocks: one for ‘did the desired state change?’, one for ‘has this object byte sequence changed at all?’.