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{    /// 
    /// Jaeger选项    /// 
    public class JaegerOptions    {        /// 
        /// 是否启用Form数据转成Span        /// 
        public bool IsFormSpan { get; set; } = false;        /// 
        /// Form数据最大长度        /// 
        public int FormValueMaxLength { get; set; } = 100;        /// 
        /// 是否启用Query数据转成Span        /// 
        public bool IsQuerySpan { get; set; } = false;        /// 
        /// Query最大长度        /// 
        public int QueryValueMaxLength { get; set; } = 100;        /// 
        /// Form或Query中不作为Span的key集合        /// 
        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{    /// 
    /// Jaeger中间件    /// 
    public class JaegerSharpMiddleware    {        /// 
        /// jaeger选项        /// 
        private readonly JaegerOptions _jaegerOptions;        /// 
        /// 日志        /// 
        private readonly ILogger
    
      _logger;        /// 
     
        /// 请求代理        /// 
        private readonly RequestDelegate _next;        public JaegerSharpMiddleware(RequestDelegate next, ILogger
     
       logger, JaegerOptions jaegerOptions = null)        {            _next = next;            _jaegerOptions = jaegerOptions;            _logger = logger;        }        /// 
      
        /// 调用管道        /// 
        /// 
      上下文        /// 
      跟踪器        /// 
              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Headers                var 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Span                using (IScope scope = builder.StartActive(true))                {                    scope.Span.SetOperationName(path);                                 // 记录请求信息到span                    if (_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{    /// 
    /// 使用JaegerSharp中间件    /// 
    public static class JaegerSharpMiddlewareExtensions    {        public static IApplicationBuilder UseJaegerSharp(this IApplicationBuilder builder)        {            return builder.UseMiddleware
    
     (new JaegerOptions());        }        public static IApplicationBuilder UseJaegerSharp(this IApplicationBuilder builder, JaegerOptions jaegerOptions)        {            return builder.UseMiddleware
     
      (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{    /// 
    /// 使用Jaeger的Action过滤器添加Jaeger实列    /// 
    public class JaegerSharpAttribute : TypeFilterAttribute    {        public JaegerSharpAttribute() : base(typeof(JaegerFilterAttributeImpl))        {        }        /// 
        /// 真正实现Jaeger Scope的类        /// 
        private class JaegerFilterAttributeImpl : IActionFilter        {            private readonly ITracer _tracer;            public JaegerFilterAttributeImpl(ITracer tracer)            {                _tracer = tracer;            }            IScope _scope = null;            /// 
            /// 开始执行Action            /// 
            ///             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span                foreach (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);                    }                }            }            /// 
            /// Action结束执行            /// 
            ///             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    {        /// 
        /// 注入Jaeger        /// 
        /// 服务容器        /// Jaeger agent host        /// Jaeger agent port        /// Jaeger agent maxpacketsize        public static void AddJaegerSharp(this IServiceCollection services, string host, int port, int maxPacketSize)        {                 services.AddSingleton
    
     (serviceProvider =>            {                var loggerFactory = serviceProvider.GetRequiredService
     
      ();                              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;            });        }    }}