gistfile1.txt

package main

import (
	"fmt"
	"net/http"
	"reflect"
	"runtime"

	"github.com/codegangsta/negroni"
	"gopkg.in/airbrake/gobrake.v2"
)

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
		w.WriteHeader(http.StatusBadRequest)
		fmt.Fprintf(w, http.StatusText(http.StatusBadRequest))
	})
	mux.HandleFunc("/hello", func(w http.ResponseWriter, req *http.Request) {
		w.WriteHeader(http.StatusTeapot)
		fmt.Fprintf(w, http.StatusText(http.StatusTeapot))
	})

	airbrake := gobrake.NewNotifier(1234567, "FIXME")
	defer func() {
		if v := recover(); v != nil {
			airbrake.Notify(v, nil)
			panic(v)
		}
	}()
	defer airbrake.Flush()

	n := negroni.Classic()
	n.Use(&AirbrakeMiddleware{
		mux:      mux,
		airbrake: airbrake,
	})
	n.UseHandler(mux)
	n.Run(":3000")
}

func getFunc(fn interface{}) *runtime.Func {
	v := reflect.ValueOf(fn)
	return runtime.FuncForPC(v.Pointer())
}

type AirbrakeMiddleware struct {
	mux      *http.ServeMux
	airbrake *gobrake.Notifier
}

func (m *AirbrakeMiddleware) ServeHTTP(w http.ResponseWriter, req *http.Request, next http.HandlerFunc) {
	next(w, req)
	nw := w.(negroni.ResponseWriter)
	if nw.Status() < 300 {
		return
	}

	h, pat := m.mux.Handler(req)
	msg := fmt.Sprintf("%s %s", pat, http.StatusText(nw.Status()))
	notice := m.airbrake.Notice(msg, req, 12)

	fn := getFunc(h)
	file, line := fn.FileLine(fn.Entry())
	backtrace := []gobrake.StackFrame{{file, line, fn.Name()}}
	backtrace = append(backtrace, notice.Errors[0].Backtrace...)
	notice.Errors[0].Backtrace = backtrace

	go m.airbrake.SendNotice(notice)
}