Add test case for auto reconnect on max_connections exceeded from ser…

…ver.
patrick-othmer · Mar 25, 2022 · 17302cd · 17302cd
1 parent d8b839d
commit 17302cd
Showing 1 changed file with 63 additions and 0 deletions.
diff --git a/nats_test.go b/nats_test.go
@@ -276,6 +276,69 @@ var testServers = []string{
 	"nats://localhost:1228",
 }
 
+func TestMaxConnectionsReconnect(t *testing.T) {
+	// Join cluster on first server
+	routes := []*url.URL{&url.URL{Scheme: "nats", Host: fmt.Sprintf("127.0.0.1:%d", TEST_PORT)}}
+
+	// Start first server
+	s1Opts := natsserver.DefaultTestOptions
+	s1Opts.Port = -1
+	s1Opts.MaxConn = 2
+	s1Opts.Cluster = server.ClusterOpts{Name: "test", Host: "127.0.0.1", Port: TEST_PORT}
+	s1Opts.Routes = routes
+	s1 := RunServerWithOptions(&s1Opts)
+	defer s1.Shutdown()
+
+	// Start second server
+	s2Opts := natsserver.DefaultTestOptions
+	s2Opts.Port = -1
+	s2Opts.MaxConn = 2
+	s2Opts.Cluster = server.ClusterOpts{Name: "test", Host: "127.0.0.1", Port: TEST_PORT + 1}
+	s2Opts.Routes = routes
+	s2 := RunServerWithOptions(&s2Opts)
+	defer s2.Shutdown()
+
+	// Only explicitly connect to first server
+	var opts = Options{
+		Url:            s1.ClientURL(),
+		AllowReconnect: true,
+		MaxReconnect:   2,
+		ReconnectWait:  10 * time.Millisecond,
+		Timeout:        200 * time.Millisecond,
+	}
+
+	// Create two connections (the current max) for first server
+	nc1, _ := opts.Connect()
+	defer nc1.Close()
+	nc1.Flush()
+
+	nc2, _ := opts.Connect()
+	defer nc2.Close()
+	nc2.Flush()
+
+	if s1.NumClients() != 2 {
+		t.Fatalf("Expected 2 client connections to first server. Got %d\n", s1.NumClients())
+	}
+
+	if s2.NumClients() > 0 {
+		t.Fatalf("Expected 0 client connections to second server. Got %d\n", s2.NumClients())
+	}
+
+	// Kick one of our two server connections off first server. One client should reconnect to second server.
+	newS1Opts := s1Opts
+	newS1Opts.MaxConn = 1
+	err := s1.ReloadOptions(&newS1Opts)
+	if err != nil {
+		t.Fatalf("Unexpected error changing max_connections [%s]", err)
+	}
+
+	time.Sleep(200 * time.Millisecond)
+
+	if s2.NumClients() <= 0 || s1.NumClients() > 1 {
+		t.Fatalf("Expected client reconnection to second server.\n")
+	}
+}
+
 func TestSimplifiedURLs(t *testing.T) {
 	for _, test := range []struct {
 		name     string