caption-json-formatter

Feature

logrus's 'message(object)' json formatter with human-readable caption added.
default available caption is (it can be disabled)

• timestamp
• logLevel

and also you can use this formatter for using simple json formatter (@since v0.2.0).

Example

OutPut

1. with custom caption (nollehLog)
   

2. set logger option with unpretty print (off pritty print)
   

3. set logger without custom caption and set as pretty
   

4. use caption_json_formatter as simple json logger, to handled by other program. (like kibana, loki, whatever) it printed as

   {
     "level": "info",
     "message": {
       "request": { "method": "GET", "url": "/user/123456/balance" },
       "response": { "balance": 1000, "user": 123456 }
     },
     "time_stamp": "2023-03-05T18:16:47.165173+09:00"
   }

Available Options

key	ConsoleDefault	JsonDefault	description
TransportToJson	false	true	if enabled, the whole log (include default caption) will be marshaled to json
UseDefaultCaption	true	true	if enabled, timestamp and loglevel will be added
PrettyPrint	true	false	if enabled, the message(object) is printed as pretty json
CustomCaption	nil	nil	if has value, then the caption is attatched before message(object)
CustomCaptionPrettyPrint	false	false	if enabled, the passed custom caption is printed as pretty json
Colorize	true	false	if enabled, add predefined term color code by loglevel

Source

• initalization

// initialize log
var (
  logger = NewLogger()
)

func NewLogger() *logrus.Logger {
  log.SetFlags(log.LstdFlags | log.Lshortfile)
  log.SetOutput(os.Stdout)
  logger := logrus.New()
  logger.Level = logrus.TraceLevel
  // option 1. helper function Console makes default formatter for console
  logger.SetFormatter(caption_json_formatter.Console())

  // if you want, use default constructor and modify some option.
  // console := caption_json_formatter.Console()
  // console.CustomCaptionPrettyPrint = true
  // logger.SetFormatter(console)

  // use JsonFormatter
  // json := caption_json_formatter.Json()
  // logger.SetFormatter(json)

  // option 2. if you no need helper constructing, you can do yourself. (not recommended)
  // logger.SetFormatter(&caption_json_formatter.Formatter{ PrettyPrint: true })
  return logger
}

func Log() *caption_json_formatter.Entry {
	return &caption_json_formatter.Entry{ Entry: logrus.NewEntry(logger) }
}

• printLog

func main() {
  type Request struct {
    Url string `json:"url"`
    Method string `json:"method"`
  }
  type Response struct {
    User int `json:"user"`
    Balance int `json:"balance"`
  }
  type Message struct {
    Request Request `json:"request"`
    Response Response `json:"response"`
  }

  message := Message { Request{ "/user/123456/balance", "GET" }, Response{123456, 1000} }

  /* in current logrus implementation, there isn't way for set Custom Entry
  * hook or formatter, doesn't have opportunity for marshaling message.
  * so before pull request was made, you need to use custom function to use extended entry.
  */

  Log().Debug(message)
}

When To Use

it is useful when shows 'message' that include json to human. show as pretty format, eventhought there is nested json. (not strigified)

for example, for message

// accessData is json type that has request / reponse data
log.Debug(accessData)

[2020-01-20T16:46:08.7452971+09:00] [Debug]
{
    "request": {
        "headers": { "content-type": "application/json" },
        "method": "GET",
        "route": "/user/{userId}/balance",
        "url": "/user/123456/balance"
    },
    "response": {
        "body": {
            "userId": 123456,
            "balance": 1000
        }
    }
}

not like other formatters doing. (like below)

[2020-01-20T16:46:08.7452971+09:00] [Debug] {/"request/": { /"headers/": { /"content-type/": /"application/json/" }, /"method/": /"GET/", /"route/": /"/user/{userId}/balance/", /"url/": /"/user/123456/balance/" }, /"response/": { /"body/": { /"userId/": 123456, /"balance/": 1000 } } }

or

{ "time": "2020-01-20T16:46:08.7452971+09:00", "msg": {/"request/": { /"headers/": { /"content-type/": /"application/json/" }, /"method/": /"GET/", /"route/": /"/user/{userId}/balance/", /"url/": /"/user/123456/balance/" }, /"response/": { /"body/": { /"userId/": 123456, /"balance/": 1000 } }

or

"2020-01-20T16:46:08.7452971+09:00" {{/user/123456/balance GET} {123456 1000}}"