add a more fine-grained way to filter messages

Author: rubensayshi

slackrus.go

@@ -14,12 +14,18 @@ const (
 	VERISON = "0.0.3"
 )
 
+// Filter is a filter applied to log entries to filter out any messages which are too noisy.
+// The filter should return true if the message should be included, and false if not.
+type Filter func(entry *logrus.Entry) bool
+
 // SlackrusHook is a logrus Hook for dispatching messages to the specified
 // channel on Slack.
 type SlackrusHook struct {
 	// Messages with a log level not contained in this array
 	// will not be dispatched. If nil, all messages will be dispatched.
 	AcceptedLevels []logrus.Level
+	// Filters are applied to messages to determine if any entry should not be send out.
+	Filters        []Filter
 	HookURL        string
 	IconURL        string
 	Channel        string
@@ -64,6 +70,13 @@ func (sh *SlackrusHook) Fire(e *logrus.Entry) error {
 		color = "warning"
 	}
 
+	// If any of the filters rejects the message then we return early
+	for _, filter := range sh.Filters {
+		if !filter(e) {
+			return nil
+		}
+	}
+
 	msg := &slack.Message{
 		Username:  sh.Username,
 		Channel:   sh.Channel,

slackrus_test.go

@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"testing"
+	"time"
 
 	"github.com/johntdyer/slack-go"
 	"github.com/sirupsen/logrus"
@@ -137,3 +138,70 @@ func TestFieldSortPriorities(t *testing.T) {
 		t.Errorf("3rd field title not as expected: exp: %q, got: %q", exp, got)
 	}
 }
+
+type filterMock struct {
+	called     int
+	rejectNext bool
+}
+
+func (f *filterMock) Filter(e *logrus.Entry) bool {
+	f.called++
+
+	if f.rejectNext {
+		f.rejectNext = false
+		return false
+	}
+	return true
+}
+
+func TestFilters(t *testing.T) {
+	f := NewFixture(t)
+	defer f.Cleanup()
+
+	mock := filterMock{}
+
+	logger := logrus.New()
+	logger.AddHook(&SlackrusHook{
+		HookURL:    f.URL(),
+		Channel:    "#slack-testing",
+		Filters: []Filter{
+			mock.Filter,
+		},
+	})
+
+	logger.Info("hi there")
+	<-f.MsgRcvd
+
+	if exp, got := 1, len(f.Messages); exp != got {
+		t.Fatalf("received unexpected number of messages: exp: %d, got: %d", exp, got)
+	}
+	if mock.called != 1 {
+		t.Fatalf("filter should have been called")
+	}
+
+	logger.Info("hi there")
+	<-f.MsgRcvd
+
+	if exp, got := 2, len(f.Messages); exp != got {
+		t.Fatalf("received unexpected number of messages: exp: %d, got: %d", exp, got)
+	}
+	if mock.called != 2 {
+		t.Fatalf("filter should have been called")
+	}
+
+	// set the mock to reject the next
+	mock.rejectNext = true
+
+	logger.Info("hi there")
+
+	select {
+	case <-f.MsgRcvd:
+		t.Fatalf("did not expect a message to be send")
+	case <-time.After(10 * time.Millisecond):
+		// no message after 10ms, should be fine
+	}
+
+	if exp, got := 2, len(f.Messages); exp != got {
+		t.Fatalf("received unexpected number of messages: exp: %d, got: %d", exp, got)
+	}
+}