How to override Host header with Spring-boot-admin server

Question

I need to send a specific host value to the client app when the admin server hits the actuator endpoint. For example, I would like to be able to make the following curl request via admin server.

curl -H "Host: discovery-headless" 10.0.10.2:9080/actuator/metrics

I tried adding the following HttpHeadersProvider

 @Bean
 public HttpHeadersProvider customHttpHeadersProvider() {
    return (instance) -> {
     HttpHeaders httpHeaders = new HttpHeaders();
      String serviceName = instance.getRegistration().getName();
      String host = serviceName.contains("headless") ? serviceName : serviceName + "-headless";
      httpHeaders.add("Host", host);
      return httpHeaders;
    };
  }

and I can see that the header is present in the request but the endpoints being registered also have headless in their urls.

endpoints=Endpoints(endpoints={caches=Endpoint(id=caches, url=http://discovery-headless/actuator/caches), loggers=Endpoint(id=loggers, url=http://discovery-headless/actuator/loggers), logfile=Endpoint(id=logfile, url=http://discovery-headless/actuator/logfile),

I also tried adding a filter to webclient without using HttpHeadersProvider but I am seeing the same result. The endpoints all have the overwritten host in their urls.

@Override
  public void customize(Builder webClientBuilder) {
    webClientBuilder.filter(addHeadlessHeader());
  }

  private ExchangeFilterFunction addHeadlessHeader() {
    return (clientRequest, next) -> {
      Map<String, String> updatedHeaders = new HashMap<>();

      clientRequest.headers().forEach((key, values) -> {
        for (String value : values) {
          updatedHeaders.put(key, value);
        }
      });

      String hostHeader = updatedHeaders.get(HttpHeaders.HOST);

      if(hostHeader == null || (hostHeader != null && !hostHeader.contains("headless"))) {
        Instance service = (Instance) clientRequest.attribute("instance").get();

        if(service != null) {
          String serviceName = service.getRegistration().getName();
          hostHeader = serviceName + "-headless";
          updatedHeaders.put(HttpHeaders.HOST, hostHeader);
        }
      }

      ClientRequest updatedRequest = ClientRequest.from(clientRequest)
          .headers(headers -> headers.setAll(updatedHeaders))
          .build();
      return next.exchange(updatedRequest);
    };
  }

What is the correct way to override the Host header when making a request to a client instance?

How to override Host header with Spring-boot-admin server

0 Answers0