text: server_uri = "server_uri"
  session_key = "session_key"
  version = "version"
  appname = "appname"
  event_writer = "event_writer"
  index = "index"
  default_index = "default"
  source = "source"
  sourcetype = "sourcetype"
  data_loader = "data_loader"
  
  meta_configs = "meta_configs"
  disabled = "disabled"
  resource = "resource"
  events = "events"
  scope = "scope"
  checkpoint_dir = "checkpoint_dir"
  
  ckpt_dict = "ckpt_dict"
  inputs = "inputs"
  input_name = "input_name"
  input_data = "input_data"
  interval = "interval"
  data = "data"
  batch_size = 'batch_size'
  time_fmt = "%Y-%m-%dT%H:%M:%S"
  utc_time_fmt = "%Y-%m-%dT%H:%M:%S.%fZ"
  
  # system setting keys
  checkpoint_storage_type = "builtin_system_checkpoint_storage_type"
  
  # Possible values for checkpoint storage type
  checkpoint_auto = 'auto'
  checkpoint_kv_storage = 'kv_store'
  checkpoint_file = 'file'
  
  # For cache file
  use_cache_file = "builtin_system_use_cache_file"
  max_cache_seconds = "builtin_system_max_cache_seconds"
  # For kv store
  collection_name = "builtin_system_kvstore_collection_name"
  
  settings = "__settings__"
  configs = "__configs__"
  
  name = "name"
  config = "config"
  division = "division"
  stanza_name = "stanza_name"
  divide_key = "_divide_key"
  divide_endpoint = "_divide_endpoint"
  mod_input_name = "mod_input_name"
  global_settings = "global_settings"
  all_configs = "all_configs"
  