refactor passing around new host uuid

lib/utils/hostid/hostid.go

@@ -83,11 +83,9 @@ func ReadOrCreateFile(dataDir string) (string, error) {
 	iterationLimit := 3
 
 	for i := 0; i < iterationLimit; i++ {
-		id, err := ReadFile(dataDir)
-		if err == nil {
-			return id, nil
-		}
-		if !trace.IsNotFound(err) {
+		if read, err := ReadFile(dataDir); err == nil {
+			return read, nil
+		} else if !trace.IsNotFound(err) {
 			return "", trace.Wrap(err)
 		}
 
@@ -103,9 +101,7 @@ func ReadOrCreateFile(dataDir string) (string, error) {
 				"Please try restarting Teleport again.")
 		}
 
-		id = rawID.String()
-
-		writeFile := func() (string, error) {
+		writeFile := func(potentialID string) (string, error) {
 			unlock, err := utils.FSTryWriteLock(hostUUIDFileLock)
 			if err != nil {
 				return "", trace.Wrap(err)
@@ -118,14 +114,14 @@ func ReadOrCreateFile(dataDir string) (string, error) {
 				return "", trace.Wrap(err)
 			}
 
-			if err := WriteFile(dataDir, id); err != nil {
+			if err := WriteFile(dataDir, potentialID); err != nil {
 				return "", trace.Wrap(err)
 			}
 
-			return id, nil
+			return potentialID, nil
 		}
 
-		id, err = writeFile()
+		id, err := writeFile(rawID.String())
 		if err != nil {
 			if errors.Is(err, utils.ErrUnsuccessfulLockTry) {
 				time.Sleep(10 * time.Millisecond)