Merge pull request #152 from burke/bugsnag-hook

hooks: Add BugSnag hook

README.md

diff --git a/README.md b/README.md
index 178123d..61ba248 100644
--- a/README.md
+++ b/README.md
@@ -74,6 +74,7 @@
   "os"
   log "github.com/Sirupsen/logrus"
   "github.com/Sirupsen/logrus/hooks/airbrake"
+  "github.com/Sirupsen/logrus/hooks/bugsnag"
 )
 
 func init() {
@@ -84,6 +85,11 @@
   // an exception tracker. You can create custom hooks, see the Hooks section.
   log.AddHook(airbrake.NewHook("https://example.com", "xyz", "development"))
 
+  // Use the Bugsnag hook to report errors that have Error severity or above to
+  // an exception tracker. You can create custom hooks, see the Hooks section.
+  bugsnagHook, _ = logrus_bugsnag.NewBugsnagHook()
+  log.AddHook(bugsnagHook)
+
   // Output to stderr instead of stdout, could also be a file.
   log.SetOutput(os.Stderr)
 

hooks/bugsnag/bugsnag.go

diff --git a/hooks/bugsnag/bugsnag.go b/hooks/bugsnag/bugsnag.go
new file mode 100644
index 0000000..d20a0f5
--- /dev/null
+++ b/hooks/bugsnag/bugsnag.go
@@ -0,0 +1,68 @@
+package logrus_bugsnag
+
+import (
+	"errors"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/bugsnag/bugsnag-go"
+)
+
+type bugsnagHook struct{}
+
+// ErrBugsnagUnconfigured is returned if NewBugsnagHook is called before
+// bugsnag.Configure. Bugsnag must be configured before the hook.
+var ErrBugsnagUnconfigured = errors.New("bugsnag must be configured before installing this logrus hook")
+
+// ErrBugsnagSendFailed indicates that the hook failed to submit an error to
+// bugsnag. The error was successfully generated, but `bugsnag.Notify()`
+// failed.
+type ErrBugsnagSendFailed struct {
+	err error
+}
+
+func (e ErrBugsnagSendFailed) Error() string {
+	return "failed to send error to Bugsnag: " + e.err.Error()
+}
+
+// NewBugsnagHook initializes a logrus hook which sends exceptions to an
+// exception-tracking service compatible with the Bugsnag API. Before using
+// this hook, you must call bugsnag.Configure(). The returned object should be
+// registered with a log via `AddHook()`
+//
+// Entries that trigger an Error, Fatal or Panic should now include an "error"
+// field to send to Bugsnag.
+func NewBugsnagHook() (*bugsnagHook, error) {
+	if bugsnag.Config.APIKey == "" {
+		return nil, ErrBugsnagUnconfigured
+	}
+	return &bugsnagHook{}, nil
+}
+
+// Fire forwards an error to Bugsnag. Given a logrus.Entry, it extracts the
+// "error" field (or the Message if the error isn't present) and sends it off.
+func (hook *bugsnagHook) Fire(entry *logrus.Entry) error {
+	var notifyErr error
+	err, ok := entry.Data["error"].(error)
+	if ok {
+		notifyErr = err
+	} else {
+		notifyErr = errors.New(entry.Message)
+	}
+
+	bugsnagErr := bugsnag.Notify(notifyErr)
+	if bugsnagErr != nil {
+		return ErrBugsnagSendFailed{bugsnagErr}
+	}
+
+	return nil
+}
+
+// Levels enumerates the log levels on which the error should be forwarded to
+// bugsnag: everything at or above the "Error" level.
+func (hook *bugsnagHook) Levels() []logrus.Level {
+	return []logrus.Level{
+		logrus.ErrorLevel,
+		logrus.FatalLevel,
+		logrus.PanicLevel,
+	}
+}

hooks/bugsnag/bugsnag_test.go

diff --git a/hooks/bugsnag/bugsnag_test.go b/hooks/bugsnag/bugsnag_test.go
new file mode 100644
index 0000000..e9ea298
--- /dev/null
+++ b/hooks/bugsnag/bugsnag_test.go
@@ -0,0 +1,64 @@
+package logrus_bugsnag
+
+import (
+	"encoding/json"
+	"errors"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/bugsnag/bugsnag-go"
+)
+
+type notice struct {
+	Events []struct {
+		Exceptions []struct {
+			Message string `json:"message"`
+		} `json:"exceptions"`
+	} `json:"events"`
+}
+
+func TestNoticeReceived(t *testing.T) {
+	msg := make(chan string, 1)
+	expectedMsg := "foo"
+
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var notice notice
+		data, _ := ioutil.ReadAll(r.Body)
+		if err := json.Unmarshal(data, &notice); err != nil {
+			t.Error(err)
+		}
+		_ = r.Body.Close()
+
+		msg <- notice.Events[0].Exceptions[0].Message
+	}))
+	defer ts.Close()
+
+	hook := &bugsnagHook{}
+
+	bugsnag.Configure(bugsnag.Configuration{
+		Endpoint:     ts.URL,
+		ReleaseStage: "production",
+		APIKey:       "12345678901234567890123456789012",
+		Synchronous:  true,
+	})
+
+	log := logrus.New()
+	log.Hooks.Add(hook)
+
+	log.WithFields(logrus.Fields{
+		"error": errors.New(expectedMsg),
+	}).Error("Bugsnag will not see this string")
+
+	select {
+	case received := <-msg:
+		if received != expectedMsg {
+			t.Errorf("Unexpected message received: %s", received)
+		}
+	case <-time.After(time.Second):
+		t.Error("Timed out; no notice received by Bugsnag API")
+	}
+}