config.json

{
  "retry_interval": 20,
  "sys_interval": 10,

  "listeners": {
    "port": 1883,
    "max_connections": -1,

    "auth_plugin": {
      "plugin_path": "auth-plug.so",
      "backends": "mysql",
    }
  }
}

config.lua

retry_interval = 20
sys_interval = 10

listeners = {
  {
    port = 1883,
    max_connections = -1,

    auth_plugin = {
      plugin_path = "auth-plug.so",
      backends = "mysql",
    }
  }
}

config.yaml

retry_interval: 20
sys_interval: 10

listeners:
  one:
    port: 1883
    max_connections: -1
    
    auth_plugin:
      plugin_path: "auth_plug.so"
      backends: "mysql"