Add LogLevelSetter to recover middleware

[ant1k9]

I've come across the situation when I need to distinguish log levels for different recovered values.

For example, I want to handle all panics as ERRORs except situations when I've got panic(ErrAbortHandler). It may happen in the ProxyWithConfig middleware when the client aborts the request.

For now, we have the LogLevel and LogLevelSetter both in the RecoverConfig to not break compatibility and introduce a new feature to the recover middleware.

Usage:

config := DefaultRecoverConfig
config.LogLevelSetter = func(value interface{}) log.Lvl {
  if err, ok := value.(error); ok {
    if errors.Is(err, http.ErrAbortHandler) {
      return log.WARN
    }
  }
  return log.ERROR
}

[aldas]

maybe adding something like that to config LogErrorFunc func(c echo.Context, err error, stack []byte) error

and allowing completely custom handling with:

			defer func() {
				if r := recover(); r != nil {
					err, ok := r.(error)
					if !ok {
						err = fmt.Errorf("%v", r)
					}
					var stack []byte
					var length int

					if !config.DisablePrintStack {
						stack = make([]byte, config.StackSize)
						length = runtime.Stack(stack, !config.DisableStackAll)
						stack = stack[:length]
					}

					if config.LogErrorFunc != nil {
						err = config.LogErrorFunc(c, err, stack)
					} else if !config.DisablePrintStack {
						msg := fmt.Sprintf("[PANIC RECOVER] %v %s\n", err, stack)
						switch config.LogLevel {
						case log.DEBUG:
...
...

and create middleware as

	e.Use(middleware.RecoverWithConfig(middleware.RecoverConfig{
		LogErrorFunc: func(c echo.Context, err error, stack []byte) error {
			msg := fmt.Sprintf("[PANIC RECOVER] %v %s\n", err, stack)
			if errors.Is(err, http.ErrAbortHandler) {
				c.Logger().Warn(msg)
			} else {
				c.Logger().Error(msg)
			}
			return err
		},
	}))

it could maybe even made to return an error instead of resulting to c.Error(err) which stops handler chain returning errors upstream middlewares.

[aldas]

Although recover middleware is extremely simple middleware it has uses when you want to log something with stack. If you are not interested in stack there absolutely no need to use Echo provided middleware as it your custom one is vert easy to create. If you want to log stack I think it would be better to give users means to choose how logging is done. This is more flexible as to give them ability to choose only log level.

[aldas]

This is example for handling recovered errors - lets say more correctly

func main() {
	e := echo.New()

	e.Use(middleware.Logger())

	customRecovery := func(next echo.HandlerFunc) echo.HandlerFunc {
		return func(c echo.Context) (err error) {
			defer func() {
				if r := recover(); r != nil {
					rErr, ok := r.(error)
					if !ok {
						rErr = fmt.Errorf("%v", r)
					}
					// c.Logger().Error(rErr)  // you do not need to log here. Logger middleware is up in chain.
					err = rErr // allows upstream middlewares to receive recovered error
				}
			}()
			return next(c)
		}
	}
	e.Use(customRecovery)

	e.GET("/", func(c echo.Context) error {
		panic(errors.New("test"))
	})

	log.Fatal(e.Start(":8080"))
}

[ant1k9]

Thanks for your suggestions!

This is more flexible as to give them ability to choose only log level.

I like your idea of a more general function in the RecoverConfig. It solves our problem!

Although recover middleware is extremely simple middleware it has uses when you want to log something with stack. If you are not interested in stack there absolutely no need to use Echo provided middleware as it your custom one is vert easy to create.

We use stack traces because they provide more information for identifying the core of the problem, so why I propose to extend the config. For now, we create a copy of the current middleware for our purposes.

This is example for handling recovered errors - lets say more correctly

You're right, it's not too elaborate to create a custom middleware, but I search the compromise between adding some customization for the service and finding a way to customize an existing solution in the echo repo.

[ant1k9]

I've commited the new version of code and applied your ideas.

[codecov]

Codecov Report

Merging #2072 (4730deb) into master (aada6f9) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2072      +/-   ##
==========================================
+ Coverage   91.57%   91.59%   +0.01%     
==========================================
  Files          33       33              
  Lines        2921     2927       +6     
==========================================
+ Hits         2675     2681       +6     
  Misses        157      157              
  Partials       89       89              

Impacted Files	Coverage Δ
middleware/recover.go	84.21% <100.00%> (+2.96%)	⬆️
echo.go	94.20% <0.00%> (ø)

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[aldas]

LGTM

[lammel]

Nice, we wanted other formatting in one of our apps too, guess we could make use of that too.

[lammel]

@ant1k9 Thanks for your contribution!