Dubbo + Zipkin + Brave实现全链路追踪
最近写了一个链路追踪Demo分享下，实现了链路追踪过程中数据的记录，还有能扩展的地方，后期再继续补充。
原理参考上面文章 《Dubbo链路追踪——生成全局ID（traceId）》
实现链路追踪的目的
- 服务调用的流程信息，定位服务调用链
- 记录调用入参及返回值信息，方便问题重现
- 记录调用时间线，代码重构及调优处理
- 调用信息统计
分布式跟踪系统还有其他比较成熟的实现，例如：Naver的Pinpoint、Apache的HTrace、阿里的鹰眼Tracing、京东的Hydra、新浪的Watchman，美团点评的CAT，skywalking等。 本次主要利用Dubbo数据传播特性扩展Filter接口来实现链路追踪的目的
重点主要是zipkin及brave使用及特性,当前brave版本为 5.2.0 为 2018年8月份发布的release版本 , zipkin版本为2.2.1 所需JDK为1.8
快速启动zipkin
下载最新的zipkin并启动
wget -O zipkin.jar 'https://search.maven.org/remote_content?g=io.zipkin.java&a=zipkin-server&v=LATEST&c=exec'
java -jar zipkin.jar
输入 http://localhost:9411/zipkin/ 进入WebUI界面如下 
核心源码
代码的初步版本：方便描述
import brave.Span;
import brave.Tracer;
import brave.Tracing;
import brave.propagation.*;
import brave.sampler.Sampler;
import com.alibaba.dubbo.common.Constants;
import com.alibaba.dubbo.common.extension.Activate;
import com.alibaba.dubbo.common.json.JSON;
import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;
import com.alibaba.dubbo.remoting.exchange.ResponseCallback;
import com.alibaba.dubbo.rpc.*;
import com.alibaba.dubbo.rpc.protocol.dubbo.FutureAdapter;
import com.alibaba.dubbo.rpc.support.RpcUtils;
import zipkin2.codec.SpanBytesEncoder;
import zipkin2.reporter.AsyncReporter;
import zipkin2.reporter.Sender;
import zipkin2.reporter.okhttp3.OkHttpSender;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.Map;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
/**
* Created with IntelliJ IDEA.
*
* @author: bakerZhu
* @description:
* @modifytime:
*/
@Activate(group = {Constants.PROVIDER, Constants.CONSUMER})
public class TracingFilter implements Filter {
private static final Logger log = LoggerFactory.getLogger(TracingFilter.class);
private static Tracing tracing;
private static Tracer tracer;
private static TraceContext.Extractor<Map<String, String>> extractor;
private static TraceContext.Injector<Map<String, String>> injector;
static final Propagation.Getter<Map<String, String>, String> GETTER =
new Propagation.Getter<Map<String, String>, String>() {
@Override
public String get(Map<String, String> carrier, String key) {
return carrier.get(key);
}
@Override
public String toString() {
return "Map::get";
}
};
static final Propagation.Setter<Map<String, String>, String> SETTER =
new Propagation.Setter<Map<String, String>, String>() {
@Override
public void put(Map<String, String> carrier, String key, String value) {
carrier.put(key, value);
}
@Override
public String toString() {
return "Map::set";
}
};
static {
// 1
Sender sender = OkHttpSender.create("http://localhost:9411/api/v2/spans");
// 2
AsyncReporter asyncReporter = AsyncReporter.builder(sender)
.closeTimeout(500, TimeUnit.MILLISECONDS)
.build(SpanBytesEncoder.JSON_V2);
// 3
tracing = Tracing.newBuilder()
.localServiceName("tracer-client")
.spanReporter(asyncReporter)
.sampler(Sampler.ALWAYS_SAMPLE)
.propagationFactory(ExtraFieldPropagation.newFactory(B3Propagation.FACTORY, "user-name"))
.build();
tracer = tracing.tracer();
// 4
// 4.1
extractor = tracing.propagation().extractor(GETTER);
// 4.2
injector = tracing.propagation().injector(SETTER);
}
public TracingFilter() {
}
@Override
public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
RpcContext rpcContext = RpcContext.getContext();
// 5
Span.Kind kind = rpcContext.isProviderSide() ? Span.Kind.SERVER : Span.Kind.CLIENT;
final Span span;
if (kind.equals(Span.Kind.CLIENT)) {
//6
span = tracer.nextSpan();
//7
injector.inject(span.context(), invocation.getAttachments());
} else {
//8
TraceContextOrSamplingFlags extracted = extractor.extract(invocation.getAttachments());
//9
span = extracted.context() != null ? tracer.joinSpan(extracted.context()) : tracer.nextSpan(extracted);
}
if (!span.isNoop()) {
span.kind(kind).start();
//10
String service = invoker.getInterface().getSimpleName();
String method = RpcUtils.getMethodName(invocation);
span.kind(kind);
span.name(service + "/" + method);
InetSocketAddress remoteAddress = rpcContext.getRemoteAddress();
span.remoteIpAndPort(
remoteAddress.getAddress() != null ? remoteAddress.getAddress().getHostAddress() : remoteAddress.getHostName(),remoteAddress.getPort());
}
boolean isOneway = false, deferFinish = false;
try (Tracer.SpanInScope scope = tracer.withSpanInScope(span)){
//11
collectArguments(invocation, span, kind);
Result result = invoker.invoke(invocation);
if (result.hasException()) {
onError(result.getException(), span);
}
// 12
isOneway = RpcUtils.isOneway(invoker.getUrl(), invocation);
// 13
Future<Object> future = rpcContext.getFuture();
if (future instanceof FutureAdapter) {
deferFinish = true;
((FutureAdapter) future).getFuture().setCallback(new FinishSpanCallback(span));// 14
}
return result;
} catch (Error | RuntimeException e) {
onError(e, span);
throw e;
} finally {
if (isOneway) { // 15
span.flush();
} else if (!deferFinish) { // 16
span.finish();
}
}
}
static void onError(Throwable error, Span span) {
span.error(error);
if (error instanceof RpcException) {
span.tag("dubbo.error_msg", RpcExceptionEnum.getMsgByCode(((RpcException) error).getCode()));
}
}
static void collectArguments(Invocation invocation, Span span, Span.Kind kind) {
if (kind == Span.Kind.CLIENT) {
StringBuilder fqcn = new StringBuilder();
Object[] args = invocation.getArguments();
if (args != null && args.length > 0) {
try {
fqcn.append(JSON.json(args));
} catch (IOException e) {
log.warn(e.getMessage(), e);
}
}
span.tag("args", fqcn.toString());
}
}
static final class FinishSpanCallback implements ResponseCallback {
final Span span;
FinishSpanCallback(Span span) {
this.span = span;
}
@Override
public void done(Object response) {
span.finish();
}
@Override
public void caught(Throwable exception) {
onError(exception, span);
span.finish();
}
}
// 17
private enum RpcExceptionEnum {
UNKNOWN_EXCEPTION(0, "unknown exception"),
NETWORK_EXCEPTION(1, "network exception"),
TIMEOUT_EXCEPTION(2, "timeout exception"),
BIZ_EXCEPTION(3, "biz exception"),
FORBIDDEN_EXCEPTION(4, "forbidden exception"),
SERIALIZATION_EXCEPTION(5, "serialization exception"),;
private int code;
private String msg;
RpcExceptionEnum(int code, String msg) {
this.code = code;
this.msg = msg;
}
public static String getMsgByCode(int code) {
for (RpcExceptionEnum error : RpcExceptionEnum.values()) {
if (code == error.code) {
return error.msg;
}
}
return null;
}
}
}
- 构建客户端发送工具
- 构建异步reporter
- 构建tracing上下文
- 初始化injector 和 Extractor [tab]4.1 extractor 指数据提取对象,用于在carrier中提取TraceContext相关信息或者采样标记信息到TraceContextOrSamplingFlags 中 -4.2 injector 用于将TraceContext中的各种数据注入到carrier中,其中carrier一半是指数据传输中的载体,类似于Dubbo中Invocation中的attachment(附件集合)
- 判断此次调用是作为服务端还是客户端
- rpc客户端调用会从ThreadLocal中获取parent的 TraceContext ,为新生成的Span指定traceId及 parentId如果没有parent traceContext 则生成的Span为 root span
- 将Span绑定的TraceContext中 属性信息 Copy 到 Invocation中达到远程参数传递的作用
- rpc服务提供端 , 从invocation中提取TraceContext相关信息及采样数据信息
- 生成span , 兼容初次服务端调用
- 记录接口信息及远程IP Port
- 将创建的Span 作为当前Span (可以通过Tracer.currentSpan 访问到它) 并设置查询范围
- oneway调用即只请求不接受结果
- 如果future不为空则为 async 调用 在回调中finish span
- 设置异步回调，回调代码执行span finish() .
- oneway调用 因为不需等待返回值 即没有 cr (Client Receive) 需手动flush()
- 同步调用 业务代码执行完毕后需手动finish()
- 设置枚举类 与 Dubbo中RpcException保持对应
测试项
- Dubbo sync async oneway 测试
- RPC异常测试
- 普通业务异常测试
- 并发测试
配置方式
POM依赖添加
<dependency>
<groupId>com.github.baker</groupId>
<artifactId>Tracing</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
资源目录根路径下添加tracing.properties文件 
一次调用信息 
调用链 
调用成功失败汇总 
zipkinHost 指定zipkin服务器IP:PORT 默认为localhost:9411 serviceName 指定应用名称 默认为trace-default
调用链： 
待扩展项
- 抽象数据传输（扩展Kafka数据传输）
- 调用返回值数据打印
- 更灵活的配置方式
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