ReactorNettyRequestUpgradeStrategy WebSocket sub protocol handling broken in GatewayAutoConfiguration

[Johannes-Rost]

org.springframework.cloud.gateway.config.GatewayAutoConfiguration creates an instance of org.springframework.web.reactive.socket.server.upgrade.ReactorNettyRequestUpgradeStrategy with a reactor.netty.http.server.WebsocketServerSpec.Builder which is reused for multiple clients with different protocols.

But the Builder should not be reused: spring-projects/spring-framework#25315

I do not have a sample, but I think the referenced bug report explains the error.

This bug was introduced in 3.0.x:

@Bean
@ConditionalOnEnabledGlobalFilter(WebsocketRoutingFilter.class)
public ReactorNettyRequestUpgradeStrategy reactorNettyRequestUpgradeStrategy(
				HttpClientProperties httpClientProperties) {

	WebsocketServerSpec.Builder builder = WebsocketServerSpec.builder();
	HttpClientProperties.Websocket websocket = httpClientProperties.getWebsocket();
	PropertyMapper map = PropertyMapper.get();
	map.from(websocket::getMaxFramePayloadLength).whenNonNull().to(builder::maxFramePayloadLength);
	map.from(websocket::isProxyPing).to(builder::handlePing);

	return new ReactorNettyRequestUpgradeStrategy(builder);
}

The WebsocketServerSpec.Builder implements Supplier<WebsocketServerSpec.Builde> but does not return a fresh instance when get() is invoked.

[Johannes-Rost]

From our point of view this is a serious bug, because we use websockets for both stomp and video streams and this bug causes the video streams to stop working with spring-cloud-gateway 3.0.x.