Add logrus adapter for Logger interface (#752)

log/logrus/logrus_logger.go

@@ -0,0 +1,35 @@
+// Package logrus provides an adapter to the
+// go-kit log.Logger interface.
+package logrus
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/go-kit/kit/log"
+	"github.com/sirupsen/logrus"
+)
+
+type logrusLogger struct {
+	*logrus.Logger
+}
+
+var errMissingValue = errors.New("(MISSING)")
+
+// NewLogrusLogger returns a go-kit log.Logger that sends log events to a Logrus logger.
+func NewLogrusLogger(logger *logrus.Logger) log.Logger {
+	return &logrusLogger{logger}
+}
+
+func (l logrusLogger) Log(keyvals ...interface{}) error {
+	fields := logrus.Fields{}
+	for i := 0; i < len(keyvals); i += 2 {
+		if i+1 < len(keyvals) {
+			fields[fmt.Sprint(keyvals[i])] = keyvals[i+1]
+		} else {
+			fields[fmt.Sprint(keyvals[i])] = errMissingValue
+		}
+	}
+	l.WithFields(fields).Info()
+	return nil
+}

log/logrus/logrus_logger_test.go

@@ -0,0 +1,55 @@
+package logrus_test
+
+import (
+	"bytes"
+	"errors"
+	"strings"
+	"testing"
+
+	log "github.com/go-kit/kit/log/logrus"
+	"github.com/sirupsen/logrus"
+)
+
+func TestLogrusLogger(t *testing.T) {
+	t.Parallel()
+	buf := &bytes.Buffer{}
+	logrusLogger := logrus.New()
+	logrusLogger.Out = buf
+	logrusLogger.Formatter = &logrus.TextFormatter{TimestampFormat: "02-01-2006 15:04:05", FullTimestamp: true}
+	logger := log.NewLogrusLogger(logrusLogger)
+
+	if err := logger.Log("hello", "world"); err != nil {
+		t.Fatal(err)
+	}
+	if want, have := "hello=world\n", strings.Split(buf.String(), " ")[3]; want != have {
+		t.Errorf("want %#v, have %#v", want, have)
+	}
+
+	buf.Reset()
+	if err := logger.Log("a", 1, "err", errors.New("error")); err != nil {
+		t.Fatal(err)
+	}
+	if want, have := "a=1 err=error", strings.TrimSpace(strings.SplitAfterN(buf.String(), " ", 4)[3]); want != have {
+		t.Errorf("want %#v, have %#v", want, have)
+	}
+
+	buf.Reset()
+	if err := logger.Log("a", 1, "b"); err != nil {
+		t.Fatal(err)
+	}
+	if want, have := "a=1 b=\"(MISSING)\"", strings.TrimSpace(strings.SplitAfterN(buf.String(), " ", 4)[3]); want != have {
+		t.Errorf("want %#v, have %#v", want, have)
+	}
+
+	buf.Reset()
+	if err := logger.Log("my_map", mymap{0: 0}); err != nil {
+		t.Fatal(err)
+	}
+	if want, have := "my_map=special_behavior", strings.TrimSpace(strings.Split(buf.String(), " ")[3]); want != have {
+		t.Errorf("want %#v, have %#v", want, have)
+	}
+}
+
+type mymap map[int]int
+
+func (m mymap) String() string { return "special_behavior" }