Add error handler for Sentry error (#78)

Author: evalphobia

sentry.go

@@ -41,9 +41,10 @@ type SentryHook struct {
 	client *raven.Client
 	levels []logrus.Level
 
-	serverName   string
-	ignoreFields map[string]struct{}
-	extraFilters map[string]func(interface{}) interface{}
+	serverName    string
+	ignoreFields  map[string]struct{}
+	extraFilters  map[string]func(interface{}) interface{}
+	errorHandlers []func(entry *logrus.Entry, err error)
 
 	asynchronous bool
 
@@ -244,23 +245,30 @@ func (hook *SentryHook) Fire(entry *logrus.Entry) error {
 
 	_, errCh := hook.client.Capture(packet, nil)
 
-	if hook.asynchronous {
+	switch {
+	case hook.asynchronous:
 		// Our use of hook.mu guarantees that we are following the WaitGroup rule of
 		// not calling Add in parallel with Wait.
 		hook.wg.Add(1)
 		go func() {
 			if err := <-errCh; err != nil {
-				fmt.Println(err)
+				for _, handlerFn := range hook.errorHandlers {
+					handlerFn(entry, err)
+				}
+				hook.wg.Done()
 			}
-			hook.wg.Done()
 		}()
 		return nil
-	} else if timeout := hook.Timeout; timeout == 0 {
+	case hook.Timeout == 0:
 		return nil
-	} else {
+	default:
+		timeout := hook.Timeout
 		timeoutCh := time.After(timeout)
 		select {
 		case err := <-errCh:
+			for _, handlerFn := range hook.errorHandlers {
+				handlerFn(entry, err)
+			}
 			return err
 		case <-timeoutCh:
 			return fmt.Errorf("no response from sentry server in %s", timeout)
@@ -342,6 +350,11 @@ func (hook *SentryHook) AddExtraFilter(name string, fn func(interface{}) interfa
 	hook.extraFilters[name] = fn
 }
 
+// AddErrorHandler adds a error handler function used when Sentry returns error.
+func (hook *SentryHook) AddErrorHandler(fn func(entry *logrus.Entry, err error)) {
+	hook.errorHandlers = append(hook.errorHandlers, fn)
+}
+
 func (hook *SentryHook) formatExtraData(df *dataField) (result map[string]interface{}) {
 	// create a map for passing to Sentry's extra data
 	result = make(map[string]interface{}, df.len())

sentry_test.go

@@ -18,6 +18,7 @@ import (
 	"github.com/getsentry/raven-go"
 	pkgerrors "github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
+	"github.com/stretchr/testify/assert"
 )
 
 const (
@@ -413,3 +414,42 @@ func TestConvertStackTrace(t *testing.T) {
 		t.Error("stack traces differ")
 	}
 }
+
+func TestErrorHandler(t *testing.T) {
+	a := assert.New(t)
+
+	s, dsn := httptestNewServer(func(rw http.ResponseWriter, req *http.Request) {
+		defer req.Body.Close()
+		rw.WriteHeader(400)
+	})
+	defer s.Close()
+
+	hook, err := NewSentryHook(dsn, []logrus.Level{
+		logrus.ErrorLevel,
+	})
+	a.NoError(err, "NewSentryHook should be no error")
+
+	logger := getTestLogger()
+	logger.Hooks.Add(hook)
+
+	hook.AddErrorHandler(func(e *logrus.Entry, err error) {
+		a.Error(err, "ErrorHandler should capture error")
+		a.Contains(err.Error(), "raven: got http status 400")
+	})
+
+	err = hook.Fire(&logrus.Entry{})
+	a.Error(err, "hook.Fire should have error")
+}
+
+// create http test server
+func httptestNewServer(handler func(http.ResponseWriter, *http.Request)) (server *httptest.Server, dsn string) {
+	server = httptest.NewServer(http.HandlerFunc(handler))
+
+	fragments := strings.SplitN(server.URL, "://", 2)
+	dsn = fmt.Sprintf(
+		"%s://public:secret@%s/sentry/project-id",
+		fragments[0],
+		fragments[1],
+	)
+	return server, dsn
+}