Dubbo 全链路追踪日志的实现

目标

http接口

所有HTTP API响应体中增加traceId字段：

{
    "code": 200,
    "data": "Hello world",
    "msg": "ok",
    "traceId": "bd41aed8b2da4895a9d2b43d1ef12595"
}

dubbo接口

对于服务调用方：每次调用服务时，都需要向服务提供方传递traceId。

对于服务提供方：每次服务响应时，都需要从服务调用方获取traceId,并将该traceId传递下去，直至该响应结束。

可对traceId的命名进行规范。

如：

• req:xxa:xxx 表示 前端请求，xxa模块，序号标识xxx
• tim:xxc:xxx 表示 定时器触发，xxc模块，序号标识xxx

实现思路

http

项目内部使用org.slf4j.MDC传递traceId。
使用拦截器完成traceId的设置与清除。请求到来时，生成并设置traceId；请求结束时，清除traceId。
拦截器中无法修改HTTP响应体。可通过ControllerAdvice统一向Response Body中写入traceId。

Dubbo

使用Dubbo提供的org.apache.dubbo.rpc.Filter来完成traceId的设置与获取。

实现

1. 项目中traceId生成、传递、销毁

请求过来之后，生成traceId，并写入org.slf4j.MDC。

请求完成之后，将traceId从org.slf4j.MDC中移除。

import com.example.dubboserviceb.constants.Constants;
import org.slf4j.MDC;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.UUID;

public class TraceIdInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        // generate traceId
        String traceId = UUID.randomUUID().toString().replace("-", "");

        // put traceId
        MDC.put(Constants.TRACE_ID, traceId);

        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

        // clear traceId
        MDC.remove(Constants.TRACE_ID);
    }
}

import lombok.Data;

@Data
public class RestResponse<T> {
    private Integer code;
    private String msg;
    private T data;
    private String traceId;

    public RestResponse() {
    }

    public RestResponse(Integer code, String msg, T data) {
        this.code = code;
        this.msg = msg;
        this.data = data;
    }

    public static <T> RestResponse<T> ok(T data) {
        return new RestResponse<>(200, "ok", data);
    }

    public static <T> RestResponse<T> error(T data) {
        return new RestResponse<>(400, "error", data);
    }
}

import com.example.dubboserviceb.constants.Constants;
import com.example.dubboserviceb.utils.RestResponse;
import org.slf4j.MDC;
import org.springframework.core.MethodParameter;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;


@ControllerAdvice
public class ResponseModifyAdvice implements ResponseBodyAdvice<Object> {

    @Override
    public boolean supports(MethodParameter methodParameter, Class<? extends HttpMessageConverter<?>> aClass) {
        return true;
    }

    @Override
    public Object beforeBodyWrite(Object o, MethodParameter methodParameter, MediaType mediaType, Class<? extends HttpMessageConverter<?>> aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {

        // put traceId to response
        ((RestResponse) o).setTraceId(MDC.get(Constants.TRACE_ID));

        return o;
    }
}

Dubbo类传递

traceId的存储使用org.apache.dubbo.rpc.RpcContext(内部使用InternalThreadLocal实现)。

借助Dubbo的过滤器来实现，traceId在Dubbo服务间的读取、写入和清除。

import com.example.dubboservicea.constants.Constants;
import org.apache.dubbo.common.extension.Activate;
import org.apache.dubbo.rpc.*;
import org.slf4j.MDC;


@Activate(group = {org.apache.dubbo.common.Constants.PROVIDER, org.apache.dubbo.common.Constants.CONSUMER})
public class DubboTraceIdFilter implements Filter {

    @Override
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {

        RpcContext rpcContext = RpcContext.getContext();

        // before
        if (rpcContext.isProviderSide()) {
            // get traceId from dubbo consumer，and set traceId to MDC
            String traceId = rpcContext.getAttachment(Constants.TRACE_ID);
            MDC.put(Constants.TRACE_ID, traceId);
        }

        Result result = invoker.invoke(invocation);

        // after
        if (rpcContext.isProviderSide()) {
            // clear traceId from MDC
            MDC.remove(Constants.TRACE_ID);
        }

        return result;
    }

    @Override
    public Result onResponse(Result result, Invoker<?> invoker, Invocation invocation) {
        return result;
    }
}

另，需要在resources/META-INF/dubbo/文件夹下，创建com.alibaba.dubbo.rpc.Filter文本文件。内容为dubboTraceIdFilter=com.example.dubboservicea.filter.DubboTraceIdFilter。

而后，spring-boot配置文件中 配置dubbo的过滤器

#dubbo
dubbo:
  scan:
    base-packages: com.example.dubboservicea.provider, com.example.dubboservicea.reference
  protocol:
    name: dubbo
    port: 12101
  registry:
    address: zookeeper://118.190.204.150:20084
  provider:
    filter: dubboTraceIdFilter
  consumer:
    filter: dubboTraceIdFilter