[
  { "name": "rank0 (coordinator)", "host": "rank0", "agent_port": 8900, "gloo_port": 29560 },
  { "name": "rank1",               "host": "rank1", "agent_port": 8900, "gloo_port": 29560 },
  { "name": "rank2",               "host": "rank2", "agent_port": 8900, "gloo_port": 29560 }
]