随着微服务的普及，微服务间的调用全链路跟踪也火了起来，Jaeger(https://www.jaegertracing.io/)是CNCF孵化的全链路跟踪型项目，在.net core中，提供了一个Jaeger的Nuget(https://github.com/jaegertracing/jaeger-client-csharp)包来使用。

本例封装就是用这个Nuget包来做成asp.net core中间件和action过滤器：中间件可以把所有经过管道的请求都跟踪起来，如果觉得这样的跟踪太重，或者没有必要收集所有请求，只跟踪有链路关联的请求，那就可以用action过滤器。

定义一个Options，这是自定义跟踪收集数据的配置属性

namespace JaegerSharp
{/// <summary>/// Jaeger选项/// </summary>public class JaegerOptions{/// <summary>/// 是否启用Form数据转成Span/// </summary>public bool IsFormSpan { get; set; } = false;/// <summary>/// Form数据最大长度/// </summary>public int FormValueMaxLength { get; set; } = 100;/// <summary>/// 是否启用Query数据转成Span/// </summary>public bool IsQuerySpan { get; set; } = false;/// <summary>/// Query最大长度/// </summary>public int QueryValueMaxLength { get; set; } = 100;/// <summary>/// Form或Query中不作为Span的key集合/// </summary>public string[] NoSpanKeys { get; set; } = new string[] { "password", "pwd" };}
}

跟踪中间件，把所有的请求都收集起来

using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using OpenTracing;
using OpenTracing.Propagation;
using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;namespace JaegerSharp
{/// <summary>/// Jaeger中间件/// </summary>public class JaegerSharpMiddleware{/// <summary>/// jaeger选项/// </summary>private readonly JaegerOptions _jaegerOptions;/// <summary>/// 日志/// </summary>private readonly ILogger<JaegerSharpMiddleware> _logger;/// <summary>/// 请求代理/// </summary>private readonly RequestDelegate _next;public JaegerSharpMiddleware(RequestDelegate next, ILogger<JaegerSharpMiddleware> logger, JaegerOptions jaegerOptions = null){_next = next;_jaegerOptions = jaegerOptions;_logger = logger;}/// <summary>/// 调用管道/// </summary>/// <param name="context">上下文</param>/// <param name="tracer">跟踪器</param>/// <returns></returns>public async Task InvokeAsync(HttpContext context, ITracer tracer){_logger.LogInformation("jaeger调用");var path = context.Request.Path;if (Path.HasExtension(path)){await _next(context);}else{//接收传入的Headersvar callingHeaders = new TextMapExtractAdapter(context.Request.Headers.ToDictionary(m => m.Key, m => m.Value.ToString()));var spanContex = tracer.Extract(BuiltinFormats.HttpHeaders, callingHeaders);ISpanBuilder builder = null;if (spanContex != null){builder = tracer.BuildSpan("中间件Span").AsChildOf(spanContex);}else{builder = tracer.BuildSpan("中间件Span");}//开始设置Spanusing (IScope scope = builder.StartActive(true)){scope.Span.SetOperationName(path);             // 记录请求信息到spanif (_jaegerOptions.IsQuerySpan){foreach (var query in context.Request.Query){//包含敏感词跳出if (_jaegerOptions.NoSpanKeys.Contains(query.Key)){continue;}var value = query.Value.ToString().Length > _jaegerOptions.QueryValueMaxLength ? query.Value.ToString()?.Substring(0, _jaegerOptions.QueryValueMaxLength) : query.Value.ToString();scope.Span.SetTag(query.Key, value);}}if (_jaegerOptions.IsFormSpan && context.Request.HasFormContentType){foreach (var form in context.Request.Form){//包含敏感词跳出if (_jaegerOptions.NoSpanKeys.Contains(form.Key)){continue;}var value = form.Value.ToString().Length > _jaegerOptions.FormValueMaxLength ? form.Value.ToString()?.Substring(0, _jaegerOptions.FormValueMaxLength) : form.Value.ToString();scope.Span.SetTag(form.Key, value);}}await _next(context);}}}}
}

扩展中间件

using Microsoft.AspNetCore.Builder;namespace JaegerSharp
{/// <summary>/// 使用JaegerSharp中间件/// </summary>public static class JaegerSharpMiddlewareExtensions{public static IApplicationBuilder UseJaegerSharp(this IApplicationBuilder builder){return builder.UseMiddleware<JaegerSharpMiddleware>(new JaegerOptions());}public static IApplicationBuilder UseJaegerSharp(this IApplicationBuilder builder, JaegerOptions jaegerOptions){return builder.UseMiddleware<JaegerSharpMiddleware>(jaegerOptions);}}
}

action过滤器，用来准确收集跟踪信息

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using OpenTracing;
using OpenTracing.Propagation;
using System.Linq;namespace JaegerSharp
{/// <summary>/// 使用Jaeger的Action过滤器添加Jaeger实列/// </summary>public class JaegerSharpAttribute : TypeFilterAttribute{public JaegerSharpAttribute() : base(typeof(JaegerFilterAttributeImpl)){}/// <summary>/// 真正实现Jaeger Scope的类/// </summary>private class JaegerFilterAttributeImpl : IActionFilter{private readonly ITracer _tracer;public JaegerFilterAttributeImpl(ITracer tracer){_tracer = tracer;}IScope _scope = null;/// <summary>/// 开始执行Action/// </summary>/// <param name="context"></param>public void OnActionExecuting(ActionExecutingContext context){var path = context.HttpContext.Request.Path;var callingHeaders = new TextMapExtractAdapter(context.HttpContext.Request.Headers.ToDictionary(m => m.Key, m => m.Value.ToString()));var spanContex = _tracer.Extract(BuiltinFormats.HttpHeaders, callingHeaders);ISpanBuilder builder = null;if (spanContex != null){builder = _tracer.BuildSpan("中间件Span").AsChildOf(spanContex);}else{builder = _tracer.BuildSpan("中间件Span");}_scope = builder.StartActive(true);_scope.Span.SetOperationName(path);// 记录请求信息到spanforeach (var query in context.HttpContext.Request.Query){_scope.Span.SetTag(query.Key, query.Value);}if (context.HttpContext.Request.HasFormContentType){foreach (var form in context.HttpContext.Request.Form){_scope.Span.SetTag(form.Key, form.Value);}}}/// <summary>/// Action结束执行/// </summary>/// <param name="context"></param>public void OnActionExecuted(ActionExecutedContext context){_scope?.Dispose();}}}
}

封装Jaeger在asp.net core中的注放步骤，使注入简单

using Jaeger;
using Jaeger.Reporters;
using Jaeger.Samplers;
using Jaeger.Senders.Thrift;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using OpenTracing;
using OpenTracing.Util;
using System.Reflection;namespace JaegerSharp
{public static class JaegerSharpExtensions{/// <summary>/// 注入Jaeger/// </summary>/// <param name="services">服务容器</param>/// <param name="host">Jaeger agent host</param>/// <param name="port">Jaeger agent port</param>/// <param name="maxPacketSize">Jaeger agent maxpacketsize</param>public static void AddJaegerSharp(this IServiceCollection services, string host, int port, int maxPacketSize){     services.AddSingleton<ITracer>(serviceProvider =>{var loggerFactory = serviceProvider.GetRequiredService<ILoggerFactory>();              var reporter = new RemoteReporter.Builder().WithLoggerFactory(loggerFactory).WithSender(new UdpSender(string.IsNullOrEmpty(host) ? UdpSender.DefaultAgentUdpHost : host,port <= 100 ? UdpSender.DefaultAgentUdpCompactPort : port,maxPacketSize <= 0 ? 0 : maxPacketSize)).Build();ITracer tracer = new Tracer.Builder(Assembly.GetEntryAssembly().GetName().Name).WithReporter(reporter).WithLoggerFactory(loggerFactory).WithSampler(new ConstSampler(true)).Build();GlobalTracer.Register(tracer);return tracer;});}}
}