Merge pull request #427 from thaJeztah/19.03_backport_40232-comply_with_gelf_spec

[19.03 backport] logger/gelf: Skip empty lines to comply with spec
Upstream-commit: cf14fa7a233114525e8a21abe1e4fc153fae7d3a
Component: engine

Author: thaJeztah

components/engine/daemon/logger/gelf/gelf.go

@@ -166,6 +166,10 @@ func newGELFUDPWriter(address string, info logger.Info) (gelf.Writer, error) {
 }
 
 func (s *gelfLogger) Log(msg *logger.Message) error {
+	if len(msg.Line) == 0 {
+		return nil
+	}
+
 	level := gelf.LOG_INFO
 	if msg.Source == "stderr" {
 		level = gelf.LOG_ERR