Autoconfigure Reactor Netty for CloudFoundry endpoint

[nkolosnjaji]

CloudFoundry AppsManager actuator features aren't working with Reactor Netty by default. CloudFoundry endpoint is returning links without https so browser doesn't send request to /cloudfoundryapplication/* endpoints because they are not secure.

response from /cloudfoundryapplication

{
  "_links": {
    "httptrace": {
      "href": "http:\/\/actuator-app.cfapps.io\/cloudfoundryapplication\/httptrace",
      "templated": false
    },
...
...
  }
}

Spring Boot 2.1 is now using Reactor Netty 0.8 which has X-Forwarded-* HTTP header support.

Following configuration made Apps manager features work again with Reactor Netty

@Configuration 
class NettyConfiguration {

	@Bean
	WebServerFactoryCustomizer<NettyReactiveWebServerFactory> configure() {
		return factory -> factory.addServerCustomizers(new EventLoopNettyCustomizer());
	}

}

class EventLoopNettyCustomizer implements NettyServerCustomizer {

    @Override
    public HttpServer apply(HttpServer httpServer) {
    	return httpServer.forwarded();
    }
}

As server.use-forward-headers are autoconfigure to true for CloudFoundry and Heroku platforms, ReactiveWebServerFactoryCustomizer could use this autoconfigured value and setup servers to use forwarded headers.

[mbhave]

@nkolosnjaji thanks, but we already have an issue open for supporting X-Forwarded-* headers for WebFlux applications here.