how SpringCloud Gateway add traceId to response header?

[ZhangZangQian]

how SpringCloud Gateway add traceId to response header?

[ZhangZangQian]

spring cloud gateway 3.1.x

[darknesstm]

ClientHttpRequest clientHttpRequest = (ClientHttpRequest) allArguments[0];
        ContextCarrier contextCarrier = (ContextCarrier) objInst.getSkyWalkingDynamicField();
        CarrierItem next = contextCarrier.items();
        while (next.hasNext()) {
            next = next.next();
            clientHttpRequest.getHeaders().set(next.getHeadKey(), next.getHeadValue());
        }

BodyInserterRequestInterceptor.java#L40

[darknesstm]

Does this have anything to do with Skywalking?

You can just use the SCG Filter to add anything you want.

[lesliey]

@darknesstm I guess what what you post is from java agent, but i need to get skywalking traceId in GatewayFilter and then put it into ServerWebExchange Resposne Headers.

[lesliey]

@darknesstm I guess what what you post is from java agent, but i need to get skywalking traceId in GatewayFilter and then put it into ServerWebExchange Resposne Headers.

i mean that in SCG, i can not call objInst.getSkyWalkingDynamicField(); ; Will u post a code sample about a custom GatewayFilter?

[darknesstm]

String traceId = WebFluxSkyWalkingOperators.continueTracing(exchange, TraceContext::traceId);

exchange is org.springframework.web.server.ServerWebExchange

<dependency>
  <groupId>org.apache.skywalking</groupId>
  <artifactId>apm-toolkit-trace</artifactId>
  <version>${skywalking.version}</version>
</dependency>

<dependency>
  <groupId>org.apache.skywalking</groupId>
  <artifactId>apm-toolkit-webflux</artifactId>
  <version>${skywalking.version}</version>
</dependency>

[lesliey]

I have tried it, it shows Could not find artifact org.apache.skywalking:apm-toolkit-webflux:pom:8.9.0 in central 。 U did upload it to maven central ?

[darknesstm]

upgrade to 8.15.0

[lesliey]

I just tried 8.15.0, but it does not work as also.

public class TraceFilter implements GlobalFilter, Ordered {

  @Override
  public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {

    String skyWalkingTraceId = WebFluxSkyWalkingOperators.continueTracing(exchange, TraceContext::traceId);
    String skyWalkingSegmentId = WebFluxSkyWalkingOperators.continueTracing(exchange, TraceContext::segmentId);
    int skyWalkingSpanId = WebFluxSkyWalkingOperators.continueTracing(exchange, TraceContext::spanId);
    log.info("SkyWalking traceId {} segmentId {} spanId {}", skyWalkingTraceId, skyWalkingSegmentId, skyWalkingSpanId);
  }

  @Override
  public int getOrder() {
    return Ordered.HIGHEST_PRECEDENCE;
  }

  }

prints as follow

2023-04-23 21:21:08.715  INFO 26572 --- [ctor-http-nio-3] TraceFilter  : SkyWalking traceId N/A segmentId N/A spanId -1�

[darknesstm]

need apm-toolkit-webflux-activation-8.15.0.jar in agent's activations folder
maybe also need apm-spring-webflux-5.x-plugin-8.15.0.jar apm-spring-cloud-gateway-3.x-plugin-8.15.0.jar in agent's plugins folder

[lesliey]

Yeap, it works well finally! Thanks a lot. Maybe i should post a blog to share it.

[collery]

hello , if don't use WebFluxSkyWalkingOperators.continueTracing and not import webflux plugins . what will happen?

[collery]

@darknesstm we only use exchange.getResponse().getHeaders().set("X-Trace-ID", TraceContext.traceId()) then found tid sometime loss 😄

[darknesstm]

TraceContext.traceId() is based on a ThreadLocal, and if there is no appropriate context copying across threads, the data will be lost.

[collery]

TraceContext.traceId()是基于a的ThreadLocal，如果没有合适的context跨线程copy，数据就会丢失。

thanks