前言

在项目中使用的是skywalking做为分布式链路跟踪,但是有个问题就是只能根据追踪tid去查询,而项目上日志又未输出tid。
不过对于我们而言，首要目的就是 Trouble Shooting，出了问题需要快速定位异常出现在什么服务，整个请求的链路是怎样的。其实很简单我们只需要跟项目中的框架结合（MQ 线程池 分布式调用 分布式Job)。
在一个请求进来的时候,在 Gateway生成唯一的TraceId,以及skywalking的tid往后传递。

使用方法

<!-- Skywalking tid-->
     <dependency>
            <groupId>org.apache.skywalking</groupId>
            <artifactId>apm-toolkit-logback-1.x</artifactId>
            <version>8.9.0</version>
        </dependency>
<!-- feign-->
        <dependency>
            <groupId>io.github.openfeign</groupId>
            <artifactId>feign-core</artifactId>
            <version>10.0.1</version>
        </dependency>
<!-- MQ-->
        <dependency>
            <groupId>org.springframework.amqp</groupId>
            <artifactId>spring-amqp</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-amqp</artifactId>
        </dependency>

RabbitMQ

1. 发消息前将MDC放入header中

public class MdcMessagePostProcess implements MessagePostProcessor {


    @Override
    public Message postProcessMessage(Message message) throws AmqpException {
        Map<String, String> mdcContainer = MDC.getCopyOfContextMap();
        for (Map.Entry<String, String> m : mdcContainer.entrySet()) {
            message.getMessageProperties().setHeader(m.getKey(),m.getValue());
        }
        return message;
    }
}

2. MQ消息消费取出traceId

public class MdcReceivePostProcessors implements MessagePostProcessor {
    @Override
    public Message postProcessMessage(Message message) throws AmqpException {
        Map<String, Object> mdc= message.getMessageProperties().getHeaders();
        Map<String, String> mdcString= new HashMap<>();
        for (Map.Entry<String, Object> m : mdc.entrySet()) {

            mdcString.put(m.getKey(),m.getValue().toString());

        }
        mdcString.put(TRACE_ID_HEADER_KEY, String.valueOf(mdc.get(TRACE_ID_HEADER_KEY)));
        MDC.setContextMap(mdcString);
        return message;
    }
}

//实例化RabbitTemplate
    @Bean
    public RabbitTemplate reforeRabbitTemplate(ConnectionFactory connectionFactory)
    {
        RabbitTemplate rabbitTemplate =new RabbitTemplate(connectionFactory);
        rabbitTemplate.setBeforePublishPostProcessors(new MdcMessagePostProcess());
        rabbitTemplate.setAfterReceivePostProcessors(new MdcReceivePostProcessors());
//        rabbitTemplate.setMessageConverter(jackson2JsonMessageConverter);
        if (log.isDebugEnabled()) {
            log.debug("reforeRabbitTemplate init success");
        }
        return rabbitTemplate;
    }

SpringTask

public class MdcAwareTaskDecorator implements TaskDecorator {
    @Override
    public Runnable decorate(Runnable runnable) {
        Map<String, String> parentThreadContextMap = MDC.getCopyOfContextMap();
        return MdcTaskUtils.adaptMdcRunnable(runnable, parentThreadContextMap);
    }
}


@Slf4j
public abstract class MdcTaskUtils {

    public static Runnable adaptMdcRunnable(Runnable runnable, Map<String, String> parentThreadContextMap) {
        return () -> {
            Map<String, String> currentThreadContextMap = MDC.getCopyOfContextMap();
            log.debug("parentThreadContextMap: {}, currentThreadContextMap: {}", parentThreadContextMap,
                    currentThreadContextMap);
            Map<String, String> threadContextMapToSet = parentThreadContextMap;
            if (threadContextMapToSet == null) {
                log.info("can not find a parentThreadContextMap, maybe task is fired using scheduled task.");
                threadContextMapToSet = CollUtil.newHashMap();
                threadContextMapToSet.put(TRACE_ID_HEADER_KEY, UUID.randomUUID().toString());
            }
            if (currentThreadContextMap == null) {
                MDC.setContextMap(threadContextMapToSet);
            } else {
                log.warn(
                        "try to start a runnable task in the parent thread: {}, parentThreadContextMap: {}, currentThreadContextMap: {}",
                        Thread.currentThread(), threadContextMapToSet, currentThreadContextMap);
            }
            try {
                runnable.run();
            } finally {
                if (currentThreadContextMap == null) {
                    MDC.clear();
                }
            }
        };
    }
}

Feign

public class MdcFeignRequestInterceptor implements RequestInterceptor {
    @Override
    public void apply(RequestTemplate template) {
        template.header(TRACE_ID_HEADER_KEY, MDC.get(TRACE_ID_HEADER_KEY));
    }
}


@Bean
    public MdcFeignRequestInterceptor mdcFeignRequestInterceptor() {
        return new MdcFeignRequestInterceptor();
    }