Errors

The error library

KCD comes with a great opinionated library that allows throwing error with status code translation, metadata, stack trace, logger ...

This error library provided with kcd allows us to:

• Wrap errors

• Known the previous domain calls if we use wrap correctly across our codebase

• Attach a kind to the error (allow us to then translate the kind into HTTP status code)

• Add metadata (i.e. fields)

• Convert the error to logrus entry with stack trace ...

• Print beautifully into the stack trace

Example

Default behavior:

package main

import (
   "net/http"

   "github.com/go-chi/chi"
   
   "github.com/alexisvisco/pkg/errors"
   "github.com/alexisvisco/kcd"
)

func main() {
   r := chi.NewRouter()
   r.Post("/", kcd.Handler(YourHttpHandler, http.StatusOK))
   _ = http.ListenAndServe(":3000", r)
}



func YourHttpHandler() error {
   return errors.NewWithKind(errors.KindInternal, "this is an error")
}

// Test it : curl -XPOST 'localhost:3000'

if you throw this statement in your KCD handler you can expect the response below...

{
  "error_description": "this is an error",
  "error": "internal"
}

And a log that looks like this in your console:

┌─────────────────────────────────────────────
│ DEBUG ERROR: "this is an error"
│  at main.go:21 main.YourHttpHandler <- error happened here

ERRO[0143]  error="this is an error" method=POST params= remote="127.0.0.1:51004" request=/ stacktrace="main/main.go.YourHttpHandler:21

Note that if the error is not an internal server error or an unknown error, the logger will not appear. If the logrus level is not in debug mode, the first stacktrace will not appear.

You can see the error handling in the error hook and the error logs in the log hook.

Format of the error message

The format of an error in KCD is the one that follows:

type ErrorResponse struct {
	ErrorDescription string      `json:"error_description"`
	Error            errors.Kind `json:"error"`

	Fields   map[string]string      `json:"fields,omitempty"`
	Metadata map[string]interface{} `json:"metadata,omitempty"`
}

• error_description the human-readable description of the error (your error message)

• error the error type (internal, invalid argument, forbidden, unauthorized ...)

• fields if there is a validation error, it will set the key with the field name and the value with the message error for this field

• metadata currently only used to put the request-id if mentioned