diff --git a/vendor/github.com/sirupsen/logrus/formatter.go b/vendor/github.com/sirupsen/logrus/formatter.go
new file mode 100644
index 0000000..4088837
--- /dev/null
+++ b/vendor/github.com/sirupsen/logrus/formatter.go
@@ -0,0 +1,78 @@
+package logrus
+
+import "time"
+
+// Default key names for the default fields
+const (
+	defaultTimestampFormat = time.RFC3339
+	FieldKeyMsg            = "msg"
+	FieldKeyLevel          = "level"
+	FieldKeyTime           = "time"
+	FieldKeyLogrusError    = "logrus_error"
+	FieldKeyFunc           = "func"
+	FieldKeyFile           = "file"
+)
+
+// The Formatter interface is used to implement a custom Formatter. It takes an
+// `Entry`. It exposes all the fields, including the default ones:
+//
+// * `entry.Data["msg"]`. The message passed from Info, Warn, Error ..
+// * `entry.Data["time"]`. The timestamp.
+// * `entry.Data["level"]. The level the entry was logged at.
+//
+// Any additional fields added with `WithField` or `WithFields` are also in
+// `entry.Data`. Format is expected to return an array of bytes which are then
+// logged to `logger.Out`.
+type Formatter interface {
+	Format(*Entry) ([]byte, error)
+}
+
+// This is to not silently overwrite `time`, `msg`, `func` 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 Fields, fieldMap FieldMap, reportCaller bool) {
+	timeKey := fieldMap.resolve(FieldKeyTime)
+	if t, ok := data[timeKey]; ok {
+		data["fields."+timeKey] = t
+		delete(data, timeKey)
+	}
+
+	msgKey := fieldMap.resolve(FieldKeyMsg)
+	if m, ok := data[msgKey]; ok {
+		data["fields."+msgKey] = m
+		delete(data, msgKey)
+	}
+
+	levelKey := fieldMap.resolve(FieldKeyLevel)
+	if l, ok := data[levelKey]; ok {
+		data["fields."+levelKey] = l
+		delete(data, levelKey)
+	}
+
+	logrusErrKey := fieldMap.resolve(FieldKeyLogrusError)
+	if l, ok := data[logrusErrKey]; ok {
+		data["fields."+logrusErrKey] = l
+		delete(data, logrusErrKey)
+	}
+
+	// If reportCaller is not set, 'func' will not conflict.
+	if reportCaller {
+		funcKey := fieldMap.resolve(FieldKeyFunc)
+		if l, ok := data[funcKey]; ok {
+			data["fields."+funcKey] = l
+		}
+		fileKey := fieldMap.resolve(FieldKeyFile)
+		if l, ok := data[fileKey]; ok {
+			data["fields."+fileKey] = l
+		}
+	}
+}