[IMPROVED] Clustering: Report possible misconfiguration of peers list

server/clustering_test.go

@@ -3801,6 +3801,39 @@ func TestClusteringNodeIDInPeersArray(t *testing.T) {
 	s1.Shutdown()
 }
 
+func TestClusteringNodeWrongPeerList(t *testing.T) {
+	cleanupDatastore(t)
+	defer cleanupDatastore(t)
+	cleanupRaftLog(t)
+	defer cleanupRaftLog(t)
+
+	ns := natsdTest.RunDefaultServer()
+	defer ns.Shutdown()
+
+	l := &captureWarnLogger{}
+
+	s1Opts := getTestDefaultOptsForClustering("a", false)
+	s1Opts.Clustering.Peers = []string{"a,b,c"}
+	s1Opts.CustomLogger = l
+	s1 := runServerWithOpts(t, s1Opts, nil)
+	defer s1.Shutdown()
+
+	waitFor(t, 5*time.Second, 15*time.Millisecond, func() error {
+		var ok bool
+		l.Lock()
+		for _, line := range l.warnings {
+			if strings.Contains(line, "string with commas") {
+				ok = true
+			}
+		}
+		l.Unlock()
+		if ok {
+			return nil
+		}
+		return fmt.Errorf("Did not print warning about commas in peer list")
+	})
+}
+
 func TestClusteringUnableToContactPeer(t *testing.T) {
 	if runtime.GOOS == "windows" {
 		t.SkipNow()

server/server.go

@@ -2003,6 +2003,19 @@ func (s *StanServer) start(runningState State) error {
 		}
 		s.log.Noticef("Cluster Node ID : %s", s.info.NodeID)
 		s.log.Noticef("Cluster Log Path: %s", s.opts.Clustering.RaftLogPath)
+		if len(s.opts.Clustering.Peers) > 0 {
+			s.log.Noticef("Cluster known peers:")
+			var alert bool
+			for i, peer := range s.opts.Clustering.Peers {
+				if strings.Contains(peer, ",") {
+					alert = true
+				}
+				s.log.Noticef("peer %d: %q", i+1, peer)
+			}
+			if alert {
+				s.log.Warnf("Peer name contains ',' make sure you provided an array of peer names, not a string with commas")
+			}
+		}
 		if err := s.startRaftNode(recoveredState != nil); err != nil {
 			return err
 		}