server: Configured upon independent start as GRPC Server ; not configured when hosted to baetyl-function-mnager. 
  address: CRPC Server monitoring address, <host>:<port> 
  concurrent: 
    max: No restriction by default, and maximum number of concurrent connections. 
  message: 
    length: 
      max: Default value: 4m, Maximum message length allowed to receive/send by function instance 
  ca: CA certificate path of Server 
  key: Server-side private key path of Server 
  cert: Server-side public key path of Server 
functions: Function list 
  - name: [Must] Function name, unique in the list 
    handler: [Must] SQL expression, for example:'select * where id > 10' 
logger:Log configuration item 
  path: It is empty by default, i.e., no file is printed; if a file is appointed, it will be output to file. 
  level: Default value: Info, log level, supporting debug, info, warn and error. 
  format: Default value: Text, log print format, supporting text and json 
  age: 
    max: Default value: 15, Maximum number of days a log file is retained 
  size: 
    max: Default value: 50, Log file size limit, unit MB 
  backup: 
        max:Default value: 15, Maximum number of log files retained