http post - Fetching Request Body at Global Filters using spring-cloud-gateway

Question

I have a need of capturing the request payloads of every request for auditing purpose, However I am unable to fetch the request body at the GlobalFilter level using the ServerWebExchange object provided. The following is a snip of my code and have attempted 2 ways based on older questions raised here, Any reference or sample code will be appreciated :

Note : For the second comment block, have attempted the caching of the body via another GlobalFilter

application.yml

spring:
  cloud:
    gateway:
      routes:
        - id: service1
          uri: http://localhost:8081/
          predicates:
          - Path=/service1/**
          filters:
          - CachingRequestBodyFilter
        - id: service2
          uri: http://localhost:8082/
          predicates:
          - Path=/service2/**
          filters:
          - CachingRequestBodyFilter

GlobalFilter

public class PreGlobalFilter implements GlobalFilter {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        HttpHeaders httpHeaders = exchange.getRequest().getHeaders();

//       ServerWebExchange serverWebExchange = exchange;
//      
//       try {
//       ByteBuffer byteBuffer = Mono.from(serverWebExchange.getRequest().getBody())
//       .toFuture().get().asByteBuffer();
//       byte[] bytes = new byte[byteBuffer.capacity()];
//       while (byteBuffer.hasRemaining())
//       byteBuffer.get(bytes);
//       System.out.println(new String(bytes, Charset.forName("UTF-8")));
//       }
//       catch (Exception e) {
//       log.error(e.getStackTrace().toString());
//       }


//      try {
//          StringBuilder cachedBody = new StringBuilder();
//          Object cachedBodyAttribute = exchange
//                  .getAttribute(ServerWebExchangeUtils.CACHED_REQUEST_BODY_ATTR);
//          if (!(cachedBodyAttribute instanceof DataBuffer)) {
//              log.error("cachedBodyAttribute is null");
//          }
//          DataBuffer dataBuffer = (DataBuffer) cachedBodyAttribute;
//          cachedBody.append(
//                  StandardCharsets.UTF_8.decode(dataBuffer.asByteBuffer()).toString());
//          String bodyAsJson = cachedBody.toString();
//          log.info("body : " + bodyAsJson);
//      }
//      catch (Exception e) {
//          log.error(e.toString());
//      }

        return chain.filter(exchange);
    }
}

CachingRequestBodyFilter

public class CachingRequestBodyFilter
        extends AbstractGatewayFilterFactory<CachingRequestBodyFilter.Config> {

    public CachingRequestBodyFilter() {
        super(Config.class);
    }

    public static class Config {
    }

    public GatewayFilter apply(final Config config) {
        return (exchange, chain) -> ServerWebExchangeUtils.cacheRequestBody(exchange,
                (serverHttpRequest) -> chain
                        .filter(exchange.mutate().request(serverHttpRequest).build()));
    }
}

question from:https://stackoverflow.com/questions/65937968/fetching-request-body-at-global-filters-using-spring-cloud-gateway

Answer 1

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