Provide REST API for:
1. Load balancers to get Active/Standby nodes, for example HTTP checks are not possible currently: https://docs.aws.amazon.com/elasticloadbalancing/latest/classic/elb-healthchecks.html or with PCS/Corosync/Pacemaker it's not possible to find which node is active without log parsing or it's not possible to get node id for further processing;

2. Statistics related to the cluster itself.

For example:

$ curl -s http://localhost:10053/server | jq .
{
  "state": "running",
  "postmaster_start_time": "2019-09-24 09:22:32.555 CEST",
  "role": "master",
  "server_version": 6.0.66,
  "cluster_unlocked": false,
  "nodes": {
    "node1": node_id,
    "node2": node_id,
}

Main idea - provide interface for tools used within clouds or dynamic environments with LB tools.