From e1adb58b067537deb366533c2b2c332c70d5c928 Mon Sep 17 00:00:00 2001
From: Derek Collison <derek@nats.io>
Date: Fri, 26 Jun 2020 09:26:59 -0700
Subject: [PATCH] Support clustername change on reload, fixes #1492

Signed-off-by: Derek Collison <derek@nats.io>
---
 server/reload.go      | 29 ++++++++++++++++-------------
 server/reload_test.go | 25 +++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/server/reload.go b/server/reload.go
index aab7ff77..14bc7e3e 100644
--- a/server/reload.go
+++ b/server/reload.go
@@ -297,25 +297,28 @@ type clusterOption struct {
 }
 
 // Apply the cluster change.
-func (c *clusterOption) Apply(server *Server) {
+func (c *clusterOption) Apply(s *Server) {
 	// TODO: support enabling/disabling clustering.
-	server.mu.Lock()
+	s.mu.Lock()
 	tlsRequired := c.newValue.TLSConfig != nil
-	server.routeInfo.TLSRequired = tlsRequired
-	server.routeInfo.TLSVerify = tlsRequired
-	server.routeInfo.AuthRequired = c.newValue.Username != ""
+	s.routeInfo.TLSRequired = tlsRequired
+	s.routeInfo.TLSVerify = tlsRequired
+	s.routeInfo.AuthRequired = c.newValue.Username != ""
 	if c.newValue.NoAdvertise {
-		server.routeInfo.ClientConnectURLs = nil
-		server.routeInfo.WSConnectURLs = nil
+		s.routeInfo.ClientConnectURLs = nil
+		s.routeInfo.WSConnectURLs = nil
 	} else {
-		server.routeInfo.ClientConnectURLs = server.clientConnectURLs
-		server.routeInfo.WSConnectURLs = server.websocket.connectURLs
+		s.routeInfo.ClientConnectURLs = s.clientConnectURLs
+		s.routeInfo.WSConnectURLs = s.websocket.connectURLs
 	}
-	server.setRouteInfoHostPortAndIP()
-	server.mu.Unlock()
-	server.Noticef("Reloaded: cluster")
+	s.setRouteInfoHostPortAndIP()
+	s.mu.Unlock()
+	if c.newValue.Name != "" && c.newValue.Name != s.ClusterName() {
+		s.setClusterName(c.newValue.Name)
+	}
+	s.Noticef("Reloaded: cluster")
 	if tlsRequired && c.newValue.TLSConfig.InsecureSkipVerify {
-		server.Warnf(clusterTLSInsecureWarning)
+		s.Warnf(clusterTLSInsecureWarning)
 	}
 }
 
diff --git a/server/reload_test.go b/server/reload_test.go
index 8afe7d75..fd7623e2 100644
--- a/server/reload_test.go
+++ b/server/reload_test.go
@@ -1762,6 +1762,31 @@ func TestConfigReloadClusterNoAdvertise(t *testing.T) {
 	}
 }
 
+func TestConfigReloadClusterName(t *testing.T) {
+	s, _, conf := runReloadServerWithContent(t, []byte(`
+		listen: "0.0.0.0:-1"
+		cluster: {
+			name: "abc"
+			listen: "0.0.0.0:-1"
+		}
+	`))
+	defer os.Remove(conf)
+	defer s.Shutdown()
+
+	// Update config with a new cluster name.
+	reloadUpdateConfig(t, s, conf, `
+	listen: "0.0.0.0:-1"
+	cluster: {
+		name: "xyz"
+		listen: "0.0.0.0:-1"
+	}
+	`)
+
+	if s.ClusterName() != "xyz" {
+		t.Fatalf("Expected update clustername of \"xyz\", got %q", s.ClusterName())
+	}
+}
+
 func TestConfigReloadMaxSubsUnsupported(t *testing.T) {
 	s, _, conf := runReloadServerWithContent(t, []byte(`max_subs: 1`))
 	defer os.Remove(conf)