Add WebSocket-specific ping interval configuration option

This commit adds a new PingInterval field to WebsocketOpts that allows
setting a custom ping interval specifically for WebSocket connections,
independent from the default NATS client ping interval.

```
websocket {
  port: 8080
  ping_interval: "30s"
}
```

Signed-off-by: Waldemar Quevedo <wally@nats.io>

Author: wallyqs

server/client.go

@@ -5503,6 +5503,9 @@ func (c *client) processPingTimer() {
 	if c.kind == ROUTER && opts.Cluster.PingInterval > 0 {
 		pingInterval = opts.Cluster.PingInterval
 	}
+	if c.isWebsocket() && opts.Websocket.PingInterval > 0 {
+		pingInterval = opts.Websocket.PingInterval
+	}
 	pingInterval = adjustPingInterval(c.kind, pingInterval)
 	now := time.Now()
 	needRTT := c.rtt == 0 || now.Sub(c.rttStart) > DEFAULT_RTT_MEASUREMENT_INTERVAL
@@ -5585,6 +5588,9 @@ func (c *client) setPingTimer() {
 	if c.kind == ROUTER && opts.Cluster.PingInterval > 0 {
 		d = opts.Cluster.PingInterval
 	}
+	if c.isWebsocket() && opts.Websocket.PingInterval > 0 {
+		d = opts.Websocket.PingInterval
+	}
 	d = adjustPingInterval(c.kind, d)
 	c.ping.tmr = time.AfterFunc(d, c.processPingTimer)
 }
@@ -6619,6 +6625,9 @@ func (c *client) setFirstPingTimer() {
 	if c.kind == ROUTER && opts.Cluster.PingInterval > 0 {
 		d = opts.Cluster.PingInterval
 	}
+	if c.isWebsocket() && opts.Websocket.PingInterval > 0 {
+		d = opts.Websocket.PingInterval
+	}
 	if !opts.DisableShortFirstPing {
 		if c.kind != CLIENT {
 			if d > firstPingInterval {

server/opts.go

@@ -595,6 +595,11 @@ type WebsocketOpts struct {
 	// time needed for the TLS Handshake.
 	HandshakeTimeout time.Duration
 
+	// How often to send pings to WebSocket clients. When set to a non-zero
+	// duration, this overrides the default PingInterval for WebSocket connections.
+	// If not set or zero, the server's default PingInterval will be used.
+	PingInterval time.Duration
+
 	// Headers to be added to the upgrade response.
 	// Useful for adding custom headers like Strict-Transport-Security.
 	Headers map[string]string
@@ -1685,7 +1690,7 @@ func (o *Options) processConfigFileLine(k string, v any, errors *[]error, warnin
 	case "reconnect_error_reports":
 		o.ReconnectErrorReports = int(v.(int64))
 	case "websocket", "ws":
-		if err := parseWebsocket(tk, o, errors); err != nil {
+		if err := parseWebsocket(tk, o, errors, warnings); err != nil {
 			*errors = append(*errors, err)
 			return
 		}
@@ -5313,7 +5318,7 @@ func parseStringArray(fieldName string, tk token, lt *token, mv any, errors *[]e
 	}
 }
 
-func parseWebsocket(v any, o *Options, errors *[]error) error {
+func parseWebsocket(v any, o *Options, errors *[]error, warnings *[]error) error {
 	var lt token
 	defer convertPanicToErrorList(&lt, errors)
 
@@ -5414,6 +5419,8 @@ func parseWebsocket(v any, o *Options, errors *[]error) error {
 					o.Websocket.Headers[key] = headerValue
 				}
 			}
+		case "ping_interval":
+			o.Websocket.PingInterval = parseDuration("ping_interval", tk, mv, errors, warnings)
 		default:
 			if !tk.IsUsedVariable() {
 				err := &unknownConfigFieldErr{

server/opts_test.go

@@ -4119,3 +4119,64 @@ func TestWriteTimeoutConfigParsing(t *testing.T) {
 		}
 	}
 }
+
+func TestWebsocketPingIntervalConfig(t *testing.T) {
+	// Test with string format (duration string)
+	confFile := createConfFile(t, []byte(`
+		websocket {
+			port: 8080
+			ping_interval: "30s"
+		}
+	`))
+	opts, err := ProcessConfigFile(confFile)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if opts.Websocket.PingInterval != 30*time.Second {
+		t.Fatalf("Expected websocket ping_interval to be 30s, got %v", opts.Websocket.PingInterval)
+	}
+
+	// Test with integer format (seconds)
+	confFile = createConfFile(t, []byte(`
+		websocket {
+			port: 8080
+			ping_interval: 45
+		}
+	`))
+	opts, err = ProcessConfigFile(confFile)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if opts.Websocket.PingInterval != 45*time.Second {
+		t.Fatalf("Expected websocket ping_interval to be 45s, got %v", opts.Websocket.PingInterval)
+	}
+
+	// Test with different duration format
+	confFile = createConfFile(t, []byte(`
+		websocket {
+			port: 8080
+			ping_interval: "2m"
+		}
+	`))
+	opts, err = ProcessConfigFile(confFile)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if opts.Websocket.PingInterval != 2*time.Minute {
+		t.Fatalf("Expected websocket ping_interval to be 2m, got %v", opts.Websocket.PingInterval)
+	}
+
+	// Test without ping_interval (should be zero/unset)
+	confFile = createConfFile(t, []byte(`
+		websocket {
+			port: 8080
+		}
+	`))
+	opts, err = ProcessConfigFile(confFile)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if opts.Websocket.PingInterval != 0 {
+		t.Fatalf("Expected websocket ping_interval to be 0 (unset), got %v", opts.Websocket.PingInterval)
+	}
+}

server/websocket_test.go

@@ -4841,6 +4841,34 @@ func Benchmark_WS_Subx5_CY__4096b(b *testing.B) {
 	wsBenchSub(b, 5, true, s)
 }
 
+func TestWebsocketPingInterval(t *testing.T) {
+	opts := testWSOptions()
+	opts.Websocket.PingInterval = 200 * time.Millisecond
+
+	s := RunServer(opts)
+	defer s.Shutdown()
+
+	wsc, br := testWSCreateClient(t, false, false, opts.Websocket.Host, opts.Websocket.Port)
+	defer wsc.Close()
+
+	pingCount := 0
+	deadline := time.Now().Add(1 * time.Second)
+
+	for time.Now().Before(deadline) {
+		wsc.SetReadDeadline(time.Now().Add(1 * time.Second))
+
+		msg := testWSReadFrame(t, br)
+		if bytes.Contains(msg, []byte("PING\r\n")) {
+			pingCount++
+			pongMsg := testWSCreateClientMsg(wsBinaryMessage, 1, true, false, []byte("PONG\r\n"))
+			wsc.Write(pongMsg)
+		}
+	}
+	if pingCount < 2 {
+		t.Fatalf("Expected at least 2 PINGs, got %d", pingCount)
+	}
+}
+
 func Benchmark_WS_Subx5_CN__8192b(b *testing.B) {
 	s := sizedString(8192)
 	wsBenchSub(b, 5, false, s)