Cluster maintainer app

[akiradeveloper]

To make a cluster, you can send AddServer RPC (using lol-admin for example) to the cluster. However, this is a tedious job and easy to make a mistake. Let's automate it.

The app (maybe a server) knows a dynamic list of servers that should be included in the cluster. The app schedules AddServer and RemoveServer then execute the plan.

Maybe, the most difficult point is how to avoid making two clusters.

[akiradeveloper]

Idea:

1. The initial cluster is given.
2. The app connect the cluster by gateway.
3. The app provides API to change the list. The API can be grpc, REST or file.

[akiradeveloper]

out of scope of this library.