resolve issue with promtail not scraping target if only path changed in a simpler way that dont need mutex to sync threads (#4599)

Signed-off-by: Roger Steneteg <rsteneteg@ea.com>

clients/pkg/promtail/targets/file/filetarget.go

@@ -118,14 +118,6 @@ func (t *FileTarget) Stop() {
 	t.handler.Stop()
 }
 
-// UpdatePath updates the filetarget path
-// returns true if the path was changed
-func (t *FileTarget) UpdatePath(path string) bool {
-	curPath := t.path
-	t.path = path
-	return curPath != path
-}
-
 // Type implements a Target
 func (t *FileTarget) Type() target.TargetType {
 	return target.FileTargetType

clients/pkg/promtail/targets/file/filetargetmanager.go

@@ -243,16 +243,12 @@ func (s *targetSyncer) sync(groups []*targetgroup.Group) {
 				}
 			}
 
-			key := labels.String()
+			key := fmt.Sprintf("%s:%s", path, labels.String())
 			targets[key] = struct{}{}
-			if tgt, ok := s.targets[key]; ok {
-				if tgt.UpdatePath(string(path)) {
-					level.Debug(s.log).Log("msg", "updating target, path changed", "labels", labels.String())
-				} else {
-					dropped = append(dropped, target.NewDroppedTarget("ignoring target, already exists", discoveredLabels))
-					level.Debug(s.log).Log("msg", "ignoring target, already exists", "labels", labels.String())
-					s.metrics.failedTargets.WithLabelValues("exists").Inc()
-				}
+			if _, ok := s.targets[key]; ok {
+				dropped = append(dropped, target.NewDroppedTarget("ignoring target, already exists", discoveredLabels))
+				level.Debug(s.log).Log("msg", "ignoring target, already exists", "labels", labels.String())
+				s.metrics.failedTargets.WithLabelValues("exists").Inc()
 				continue
 			}