你是否发现网关gateway日志是不产生链路ID的，都是(N/A)，所以网关的skywalking还要稍微处理一下。
其实gateway是有TID生成的，所以我们只要把TID手动放到log4j2的org.slf4j.MDC里面就好了，完整代码：
package com.tczscloud.gateway.frame.filter;
import io.netty.buffer.ByteBufAllocator;
import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.core.io.buffer.NettyDataBufferFactory;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpRequestDecorator;
import org.springframework.stereotype.Component;
import org.springframework.util.MultiValueMap;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import org.slf4j.MDC;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.URI;
import java.nio.charset.StandardCharsets;
/**
* 请求日志过滤器
*
* @author 2020/11/10
*/
@Component
@Slf4j
public class RequestLogFilter implements GlobalFilter, Ordered {
@SneakyThrows
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
putTidIntoMdc(exchange);
ServerHttpRequest serverHttpRequest = exchange.getRequest();
String method = serverHttpRequest.getMethodValue();
if ("POST".equals(method)) {
return DataBufferUtils.join(exchange.getRequest().getBody())
.flatMap(dataBuffer -> {
byte[] bytes = new byte[dataBuffer.readableByteCount()];
dataBuffer.read(bytes);
String bodyStr = new String(bytes, StandardCharsets.UTF_8);
log.info("------------------------------- POST请求参数 ------------------------------------");
log.info(bodyStr);
//TODO 拿到POST日志后的操作
//下面的将请求体再次封装写回到request里，传到下一级，否则，由于请求体已被消费，后续的服务将取不到值
URI uri = serverHttpRequest.getURI();
ServerHttpRequest request = serverHttpRequest.mutate().uri(uri).build();
DataBuffer bodyDataBuffer = this.stringBuffer(bodyStr);
Flux<DataBuffer> bodyFlux = Flux.just(bodyDataBuffer);
request = new ServerHttpRequestDecorator(request) {
@Override
public Flux<DataBuffer> getBody() {
return bodyFlux;
}
};
//封装request，传给下一级
return chain.filter(exchange.mutate().request(request).build());
});
} else if ("GET".equals(method)) {
MultiValueMap<String, String> queryParams = serverHttpRequest.getQueryParams();
//TODO 得到Get请求的请求参数后，做你想做的事
log.info("------------------------------- GET请求参数 ------------------------------------");
log.info(queryParams.toString());
return chain.filter(exchange);
}
return chain.filter(exchange);
}
/**
* tid放入MDC 请求开始和请求返回是两个线程，每个线程都要放
*
* @param exchange
*/
public static void putTidIntoMdc(ServerWebExchange exchange) {
try {
Object entrySpanInstance = exchange.getAttributes().get("SKYWALKING_SPAN");
if (entrySpanInstance == null) {
return;
}
Class<?> entrySpanClazz = entrySpanInstance.getClass().getSuperclass().getSuperclass();
Field field = entrySpanClazz.getDeclaredField("owner");
field.setAccessible(true);
Object ownerInstance = field.get(entrySpanInstance);
Class<?> ownerClazz = ownerInstance.getClass();
Method getTraceId = ownerClazz.getMethod("getReadablePrimaryTraceId");
String traceId = (String) getTraceId.invoke(ownerInstance);
MDC.putCloseable("traceId", traceId);
} catch (Exception e) {
log.error("gateway追踪码获取失败", e);
}
}
private DataBuffer stringBuffer(String value) {
byte[] bytes = value.getBytes(StandardCharsets.UTF_8);
NettyDataBufferFactory nettyDataBufferFactory = new NettyDataBufferFactory(ByteBufAllocator.DEFAULT);
DataBuffer buffer = nettyDataBufferFactory.allocateBuffer(bytes.length);
buffer.write(bytes);
return buffer;
}
@Override
public int getOrder() {
return 0;
}
}
<Property name="logging.lemes.pattern">
%d{yyyy-MM-dd HH:mm:ss.SSS} [%-5level] traceId:%X{traceId} [%logger{50}.%M:%L] - %msg%n
</Property>skywalking默认是不支持网关的，所以还要在skywalking-agent解压包下的可选插件optional-plugins目录下，找到apm-spring-cloud-gateway-3.x-plugin-9.2.0.jar和spring-webflux-5.x-webclient-plugin-9.2.0.jar丢到已安装插件plugins目录下。（注意gateway3和webflux5都是要对应你的gateway项目的版本）。然后重新启动gateway就可以了。
问题：
上门过滤器的日志gateway的log4j日志文件确实有链路ID了，也能在skywalking上查询到了。但是在skywalking上是没有追踪id的，导致这几行日志没有在链路上。解决了很久，还是没有解决了，不过gateway也没啥操作，不需要啥日志，少了这层就少了这层把，排查问题还是在其他业务服务上，而且gateway是有日志的，只是不能自动串联，需要我们可以手动串联如果需要gatewat输出日志配合。有解决的可以提供一下方法。