# README

Glogger

Glogger is the logger for mia-platform go services.

It uses logrus as logging library, and implements a middleware to be used with http gorilla mux router and fiber.

This library follow the Mia Platform logging guidelines.

Install

This library require golang at version >= 1.13

go get -u github.com/mia-platform/glogger/v3

Example usage

Basic logger initialization.

The allowed log level are those parsed by logrus ParseLevel (e.g. panic, fatal, error, warn, warning, info, debug, trace).

// Logger setup
log, err := glogger.InitHelper(glogger.InitOptions{Level: "info"})
if err != nil {
	msg := fmt.Sprintf("An error occurred while creating the logger: %v", err)
	panic(msg)
}

Setup log middleware

Two middleware loggers are available in the middleware package of this library. To use them you need to import it:

import "github.com/mia-platform/glogger/v3/middleware"

Gorilla Mux

Init log middleware for mux router. This log the incoming request and request completed following the mia-platform guidelines.

r := mux.NewRouter()
r.Use(middleware.RequestGorillaMuxMiddlewareLogger(log, nil))

and, to retrieve logger injected in request context:

func(w http.ResponseWriter, req *http.Request) {
  loggerFn := glogger.Get(req.Context())
  loggerFn.Info("log message")
}

Fiber

With fiber, you can setup the middleware in this way:

app := fiber.New()
app.Use(middleware.RequestFiberMiddlewareLogger())

And then retrieve it from the handler's context like this:

func(c *fiber.Ctx) {
  loggerFn := glogger.Get(c.UserContext())
  loggerFn.Info("log message")
}

with excluded path

You can restrict the path where the logger middleware take effect using the second paramenter in RequestGorillaMuxMiddlewareLogger. For example, this could be useful to exclude incoming request and request completed logging in path router.

Logger function is injected anyway in request context.

r := mux.NewRouter()
r.Use(middleware.RequestGorillaMuxMiddlewareLogger(log, []string{"/-/"}))

How to log error message

To log error message using default field

_, err := myFn()

if err != nil {
  glogger.Get(req.Context()).WithError(err).Error("error calling function")
}

How to log custom fields

To log error message using default field

glogger.Get(req.Context()).WithField("key", "some field").Info("error calling function")

glogger.Get(req.Context()).WithFields(&logrus.Fields{
  "key": "some field",
  "another-key": "something"
}).Info("log with custom fields")