adlaika / graflog

monadic correlated log events

Graflog

Monadic correlated log events!

##To Use:

• given a data type:

  data UserSpec = UserSpec
    { email :: Email
    , password :: Text
    , name :: Text
    } deriving (Eq, Show, Generic)
  

  we can create an instance of ToLog:

  instance ToLog UserSpec where
    toLog UserSpec{email, name} =
      dictionary
        [ pair "email" email
        , pair "password" Redacted
        , pair "name" name ]
  

  and derive JSON instances of that:

  deriveJSON defaultOptions ''UserSpec
  

  which can then be logged inside a monad:

  foo = do
    let jimbo = UserSpec (Email "[email protected]" ...)
    logJSON $ Event (CorrelationId 0) (EventId 0) "User" (toLog jimbo)
    return jimbo
  

• you must force stdout to flush after each line, or logs won't appear in a timely manner: call Graflog.Console.enableStdoutLineBuffering at the top of your main function.

• CorrelationId and EventId generation are not yet supported, so you must create an event manually:

  • inside do notation: let event = Event (CorrelationId 0) (EventId 0)
  • followed at some point by: logJSON $ event (Action "some kind of metadata") (toLog dataToLog)

##To Do:

• CorrelationId and EventId generation
• Generic derivation of ToLog / ToJSON instances
• Support for non-JSON logging?