How can I know which node execute the certain operation?

I have a cluster with following setup:
3 master nodes
3 data nodes,
and I have defined a policy that moves index into a read_only state after one day and then deletes it after a set period of 3 days.
After one day, the index automatic moved to read_only, but how can I know which node triggers the operation? It’s triggered by master node or data node?