Etcd_initial_cluster_state

[fatemeap4]

Hello everyone
Can somebody explain to me that is there any force to declare Etcd_initial_cluster_state in configuration?
I tried to implement etcd with 3node via ansible and the problem is when I test my role by molecule,I will not get idempotence response
After I checked what's the cause of changes in second test run, I found out 'new' value assign to nodes, after re-run this value turns to existing.
When I delete this configuration parameter everythings gonna be alright and pass through my pipeline

So can somebody explain the importance of this parameter? Can I be survive without using it?:)