TUN-528: Move cloudflared into a separate repo

log/log.go

@@ -0,0 +1,85 @@
+// this forks the logrus json formatter to rename msg -> message as that's the
+// expected field. Ideally the logger should make it easier for us.
+package log
+
+import (
+	"encoding/json"
+	"fmt"
+	"runtime"
+	"time"
+
+	"github.com/mattn/go-colorable"
+	"github.com/sirupsen/logrus"
+)
+
+var (
+	DefaultTimestampFormat = time.RFC3339
+)
+
+type JSONFormatter struct {
+	// TimestampFormat sets the format used for marshaling timestamps.
+	TimestampFormat string
+}
+
+func CreateLogger() *logrus.Logger {
+	logger := logrus.New()
+	logger.Out = colorable.NewColorableStderr()
+	logger.Formatter = &logrus.TextFormatter{ForceColors: runtime.GOOS == "windows"}
+	return logger
+}
+
+func (f *JSONFormatter) Format(entry *logrus.Entry) ([]byte, error) {
+	data := make(logrus.Fields, len(entry.Data)+3)
+	for k, v := range entry.Data {
+		switch v := v.(type) {
+		case error:
+			// Otherwise errors are ignored by `encoding/json`
+			// https://github.com/sirupsen/logrus/issues/137
+			data[k] = v.Error()
+		default:
+			data[k] = v
+		}
+	}
+	prefixFieldClashes(data)
+
+	timestampFormat := f.TimestampFormat
+	if timestampFormat == "" {
+		timestampFormat = DefaultTimestampFormat
+	}
+
+	data["time"] = entry.Time.Format(timestampFormat)
+	data["message"] = entry.Message
+	data["level"] = entry.Level.String()
+
+	serialized, err := json.Marshal(data)
+	if err != nil {
+		return nil, fmt.Errorf("Failed to marshal fields to JSON, %v", err)
+	}
+	return append(serialized, '\n'), nil
+}
+
+// This is to not silently overwrite `time`, `msg` and `level` fields when
+// dumping it. If this code wasn't there doing:
+//
+//  logrus.WithField("level", 1).Info("hello")
+//
+// Would just silently drop the user provided level. Instead with this code
+// it'll logged as:
+//
+//  {"level": "info", "fields.level": 1, "msg": "hello", "time": "..."}
+//
+// It's not exported because it's still using Data in an opinionated way. It's to
+// avoid code duplication between the two default formatters.
+func prefixFieldClashes(data logrus.Fields) {
+	if t, ok := data["time"]; ok {
+		data["fields.time"] = t
+	}
+
+	if m, ok := data["msg"]; ok {
+		data["fields.msg"] = m
+	}
+
+	if l, ok := data["level"]; ok {
+		data["fields.level"] = l
+	}
+}