Jaeger配置

pom.xml

<dependency>
    <groupId>io.opentracing.contrib</groupId>
    <artifactId>opentracing-spring-jaeger-cloud-starter</artifactId>
    <version>3.3.1</version>
</dependency>

<!-- feign -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
    <version>3.0.6</version>
</dependency>
<dependency>
    <groupId>io.github.openfeign.opentracing</groupId>
    <artifactId>feign-opentracing</artifactId>
    <version>0.4.0</version>
</dependency>

<!-- log -->
<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.2.13</version>
</dependency>

application.yml

opentracing:
  jaeger:
    enabled: true
    enable-b3-propagation: true
    log-spans: true
    http-sender:
      url: http://<jaeger-collector-service-name>:14268/api/traces
    rate-limiting-sampler:
      max-traces-per-second: 5

配置traceId, spanid等的key

@Configuration
public class JaegerConfiguration {

    public static final String TRACE_ID_NAME = "X-B3-TraceId";
    public static final String SPAN_ID_NAME = "X-B3-SpanId";
    public static final String SAMPLED_NAME = "X-B3-Sampled";

    @Bean
    public TracerBuilderCustomizer mdcBuilderCustomizer() {
        return builder -> builder.withScopeManager(new MDCScopeManager.Builder().
                withMDCSpanIdKey(SPAN_ID_NAME).
                withMDCTraceIdKey(TRACE_ID_NAME).
                withMDCSampledKey(SAMPLED_NAME).
                build());
    }

    @Bean
    @Order(Ordered.HIGHEST_PRECEDENCE)
    @ConditionalOnProperty(prefix = "opentracing.jaeger.neverReport", value = "enabled", matchIfMissing = true)
    public Reporter reporter(JaegerConfigurationProperties properties,
                             @Autowired(required = false) ReporterAppender reporterAppender) {
        List<Reporter> reporters = new LinkedList<>();
        if (properties.isLogSpans()) {
            reporters.add(new LoggingReporter());
        }
        if (reporterAppender != null) {
            reporterAppender.append(reporters);
        }
        return new CompositeReporter(reporters.toArray(new Reporter[reporters.size()]));
    }
}

打印日志时使用%X将追踪信息打印出来，logback-spring.xml:

...
<pattern>
{
  ...
  "trace": "%X{X-B3-TraceId:-}",
  "span": "%X{X-B3-SpanId:-}",
  "sample": "%X{X-B3-Sampled:-}",
  ...
}
</pattern>
...

全链路请求追踪，主要包括两部分：

一、线程内共享上下文，通过ThreadLocal实现

public class LogbackMDCAdapter implements MDCAdapter {
    final ThreadLocal<Map<String, String>> copyOnThreadLocal = new ThreadLocal();

    public void put(String key, String val) throws IllegalArgumentException {
        if (key == null) {
            throw new IllegalArgumentException("key cannot be null");
        } else {
            Map<String, String> oldMap = (Map)this.copyOnThreadLocal.get();
            Integer lastOp = this.getAndSetLastOperation(1);
            if (!this.wasLastOpReadOrNull(lastOp) && oldMap != null) {
                oldMap.put(key, val);
            } else {
                Map<String, String> newMap = this.duplicateAndInsertNewMap(oldMap);
                newMap.put(key, val);
            }

        }
    }

    public void remove(String key) {
        if (key != null) {
            Map<String, String> oldMap = (Map)this.copyOnThreadLocal.get();
            if (oldMap != null) {
                Integer lastOp = this.getAndSetLastOperation(1);
                if (this.wasLastOpReadOrNull(lastOp)) {
                    Map<String, String> newMap = this.duplicateAndInsertNewMap(oldMap);
                    newMap.remove(key);
                } else {
                    oldMap.remove(key);
                }

            }
        }
    }

    public void clear() {
        this.lastOperation.set(1);
        this.copyOnThreadLocal.remove();
    }

    public String get(String key) {
        Map<String, String> map = (Map)this.copyOnThreadLocal.get();
        return map != null && key != null ? (String)map.get(key) : null;
    }
    
    ...
}

二、跨进程上下文传递，通过将上下文信息放入http header中实现

Feign中的实现（io.github.openfeign.opentracing:feign-opentracing）

TracingClient.java

    @Override
    public Response execute(Request request, Request.Options options) throws IOException {
        Span span = tracer.buildSpan(request.method())
            .withTag(Tags.SPAN_KIND.getKey(), Tags.SPAN_KIND_CLIENT)
            .start();

        for (FeignSpanDecorator spanDecorator: spanDecorators) {
            try {
                spanDecorator.onRequest(request, options, span);
            } catch (Exception ex) {
                log.log(Level.SEVERE, "Exception during decorating span", ex);
            }
        }

        request = inject(span.context(), request);

        try (Scope scope = tracer.activateSpan(span)) {
            Response response = delegate.execute(request, options);
            for (FeignSpanDecorator spanDecorator : spanDecorators) {
                try {
                    spanDecorator.onResponse(response, options, span);
                } catch (Exception ex) {
                    log.log(Level.SEVERE, "Exception during decorating span", ex);
                }
            }
            return response;
        } catch (Exception ex) {
            for (FeignSpanDecorator spanDecorator: spanDecorators) {
                try {
                    spanDecorator.onError(ex, request, span);
                } catch (Exception exDecorator) {
                    log.log(Level.SEVERE, "Exception during decorating span", exDecorator);
                }
            }

            throw ex;
        } finally {
            span.finish();
        }
    }

    private Request inject(SpanContext spanContext, Request request) {
        Map<String, Collection<String>> headersWithTracingContext = new HashMap<>(request.headers());
        tracer.inject(spanContext, Format.Builtin.HTTP_HEADERS, new HttpHeadersInjectAdapter(headersWithTracingContext));
        return request.create(request.method(), request.url(), headersWithTracingContext,request.body(),
                request.charset());
    }

RestTemplate的实现（io.opentracing.contrib:opentracing-spring-web）

TracingRestTemplateInterceptor.java

    @Override
    public ClientHttpResponse intercept(HttpRequest httpRequest, byte[] body,
                                        ClientHttpRequestExecution execution) throws IOException {
        ClientHttpResponse httpResponse;

        Span span = tracer.buildSpan(httpRequest.getMethod().toString())
                .withTag(Tags.SPAN_KIND.getKey(), Tags.SPAN_KIND_CLIENT)
                .start();
        tracer.inject(span.context(), Format.Builtin.HTTP_HEADERS,
                new HttpHeadersCarrier(httpRequest.getHeaders()));

        for (RestTemplateSpanDecorator spanDecorator : spanDecorators) {
            try {
                spanDecorator.onRequest(httpRequest, span);
            } catch (RuntimeException exDecorator) {
                log.error("Exception during decorating span", exDecorator);
            }
        }

        try (Scope scope = tracer.activateSpan(span)) {
            httpResponse = execution.execute(httpRequest, body);
            for (RestTemplateSpanDecorator spanDecorator : spanDecorators) {
                try {
                    spanDecorator.onResponse(httpRequest, httpResponse, span);
                } catch (RuntimeException exDecorator) {
                    log.error("Exception during decorating span", exDecorator);
                }
            }
        } catch (Exception ex) {
            for (RestTemplateSpanDecorator spanDecorator : spanDecorators) {
                try {
                    spanDecorator.onError(httpRequest, ex, span);
                } catch (RuntimeException exDecorator) {
                    log.error("Exception during decorating span", exDecorator);
                }
            }
            throw ex;
        } finally {
            span.finish();
        }

        return httpResponse;
    }