gistfile1.lua

require "cjson"

local dt = require 'date_time'
-- Generic decoder for JSON logs. This will extract all JSON
-- keys and add them to the `Fields` variable of the created
-- Heka message.
--
-- Example use:
--
-- [NginxJsonLogDecoder]
-- type = "SandboxDecoder"
-- script_type = "lua"
-- filename = "/location/of/json_log_decode.lua"
--
-- [NginxJsonLogDecoder.config]
-- app = "some application"
--
-- [some-nginx-json-log-file]
-- type = "LogfileInput"
-- logfile = "/some/location/of/an/nginx/log/file.json.log"
-- decoder = "NginxJsonLogDecoder"

function process_message()
   local raw_message = read_message("Payload")

   local json = cjson.decode(raw_message)
   if not json then
      -- When plain text is found, ship it in it's raw form.
      inject_message(raw_message)
      return 0
   end

   local message = {
      Type = "jsonLog"
   }

   message.Payload = json['message']
   json['message'] = null

   message.Hostname = json['HOSTNAME']
   json['HOSTNAME'] = null

   message.Logger = json['logger_name']
   json['logger_name'] = null

   message.Fields = json

   -- 2014-07-31T11:56:34.305+02:00
   local fields = dt.rfc3339:match(json["@timestamp"])
   json["@timestamp"] = null
   message.Timestamp = dt.time_to_ns(fields)
   inject_message(message)
   return 0
end