move dependencies to vendor

vendor/github.com/Sirupsen/logrus/json_formatter.go

@@ -0,0 +1,41 @@
+package logrus
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+type JSONFormatter struct {
+	// TimestampFormat sets the format used for marshaling timestamps.
+	TimestampFormat string
+}
+
+func (f *JSONFormatter) Format(entry *Entry) ([]byte, error) {
+	data := make(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["msg"] = 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
+}