ASP.NET Core中使用Graylog记录日志

如下基于.NET Core 2.1

定义GrayLog日志记录中间件：

中间件代码：

public class GrayLogMiddleware { private readonly RequestDelegate _next; private readonly ILogger _logger; ​ //在应用程序的生命周期中，中间件的构造函数只会被调用一次
     public GrayLogMiddleware(RequestDelegate next, ILoggerFactory loggerFactory) { _next = next; _logger = loggerFactory.CreateLogger("GrayLog"); } ​ public async Task InvokeAsync(HttpContext context) { var additionalFields = new Dictionary<string, object>() { ["LogId"] = Guid.NewGuid() }; ​ // 若将该中间件作为第一个请求管道中的第一个中间件进行注册 // 那么在此处就能够进行全局异常处理
         try { var startTime = DateTime.Now; await _next(context); var endTime = DateTime.Now; additionalFields["Elapsed"] = (endTime - startTime).Milliseconds; _logger.LogInfo(context, additionalFields); } catch (Exception ex) { if (context.Response.HasStarted == false) { await WriteExceptionInfoIntoResponseAsync(context, ex); } _logger.LogException(context, ex, additionalFields); #if DEBUG
             throw; #endif } } ​ private async Task WriteExceptionInfoIntoResponseAsync(HttpContext context, Exception ex) { try { var resp = new ApiResponse(); resp = resp.Exception(ex); var respStr = JsonConvert.SerializeObject(resp); await context.Response.WriteAsync(respStr, Encoding.UTF8); } catch { // ignore
 } } ​ }

日志记录代码：

​

public static class LogExtension { public static void LogInfo(this ILogger logger, HttpContext context, IDictionary<string, object> addtionalFields = null) { logger.LogCore(context, LogLevel.Information, addtionalFields: addtionalFields); } ​ public static void LogException(this ILogger logger, HttpContext context, Exception ex, IDictionary<string, object> addtionalFields = null) { logger.LogCore(context, LogLevel.Error, ex, addtionalFields); } ​ private static void LogCore(this ILogger logger, HttpContext context, LogLevel logLevel, Exception ex = null, IDictionary<string, object> addtionalFields = null) { try { var shortMessage = GetShortMessage(context); if (addtionalFields == null) { addtionalFields = GetAddtionalFields(context); } else { var temp = GetAddtionalFields(context); addtionalFields = addtionalFields.Union(temp).ToDictionary(d => d.Key, d => d.Value); } ​ // 须要使用Scope才能将additionalFields记录到GrayLog中
            using (logger.BeginScope(addtionalFields)) { logger.Log(logLevel, exception: ex, message: shortMessage); } } catch { #if DEBUG
            throw; #endif
            // ignore
 } } ​ /// <summary>
    /// 获取请求的短消息 /// <para>
    /// 消息格式：HttpMethod RequestUrl HttpStatusCode /// </para>
    /// </summary>
    /// <example> GET http://localhost:5000 200</example>
    private static string GetShortMessage(HttpContext context) { var request = context.Request; ​ var method = request.Method; var url = request.GetEncodedUrl(); var statusCode = context.Response.StatusCode; ​ return $"{method} {url} {statusCode}"; } ​ /// <summary>
    /// 须要写入到日志中的额外字段：请求来源，请求参数 /// </summary>
    private static IDictionary<string, object> GetAddtionalFields(HttpContext context) { var referer = context.Connection.RemoteIpAddress; var requestData = GetRequestParameters(context); ​ return new Dictionary<string, object>() { ["Referer"] = referer, ["RequestData"] = requestData }; } ​ private static string GetRequestParameters(HttpContext context) { if (context.Request.ContentLength > 0) { var stream = context.Request.Body; if (stream.CanRead == false) { return null; } if (stream.CanSeek == false) { // 将HttpRequestStream转换为FileBufferingReadStream
 context.Request.EnableBuffering(); stream = context.Request.Body; } stream.Position = 0; ​ using (var reader = new StreamReader(stream)) { var data = reader.ReadToEnd(); return data; } } ​ return null; } ​ }

 

Graylog日志配置：

public class Program { public static void Main(string[] args) => CreateWebHost().Run(); ​ private static IWebHost CreateWebHost() => CreateWebHostBuilder().Build(); ​ // 这里未使用.NET Core封装的CreateDefaultBuilder方法，由于它封装了过多不须要的东西
        private static IWebHostBuilder CreateWebHostBuilder() =>
               new WebHostBuilder() .UseContentRoot(Directory.GetCurrentDirectory()) #if RELEASE .UseIISIntegration() #endif .UseKestrel() .ConfigureLogging((context, builder) => { ConfigLogger(context, builder); }) .UseStartup<Startup>(); ​ private static void ConfigLogger(WebHostBuilderContext context, ILoggingBuilder builder) { // 使用日志过滤器(log filtering)，禁止Kestrel记录访问日志
 builder.ClearProviders(); builder.AddFilter("Microsoft", LogLevel.None); builder.AddFilter("System", LogLevel.Error); ​ if (context.HostingEnvironment.IsDevelopment()) { builder.AddDebug(); } ​ // GrayLog配置（这里使用App.config做为配置文件
            builder.AddGelf(option => { option.Host = ConfigurationManager.AppSettings["grayLogHost"]; option.Port = Convert.ToInt32(ConfigurationManager.AppSettings["grayLogPort"]); option.LogSource = ConfigurationManager.AppSettings["grayLogSource"]; option.Protocol = GelfProtocol.Udp; }); } }

 

注册中间件到请求处理管道：

public static class GrayLogMiddlewareExtension { /// <summary>
    /// 向请求管道中添加GrayLog记录功能及全局异常处理 /// </summary>
    public static IApplicationBuilder UseGrayLog(this IApplicationBuilder builder) => builder.UseMiddleware<GrayLogMiddleware>(); } ​ public class Startup { public void Configure(IApplicationBuilder app) { app.UseGrayLog() .UseMvc(); } }

 

以上日志记录了以下几个方面：

1. 日志信息Id

2. 请求来源

3. 请求基础信息

   采用相似HTTP请求行格式，即：HttpMethod RequestUrl ResponseStatusCode，如：GET http://localhost 200

4. 入参

5. 接口耗时

6. 若发生异常，则记录异常信息

HttpRequestStream vs FileBufferingReadStream

GET请求参数都体如今Url中了，这里讲述如何获取POST请求的参数。

一般POST请求数据都在请求体中，ASP.NET Core中HttpRequest类型的Body属性是HttpRequestStream类型，该类型源码在Github上能够看到，但在Google和微软关方文档中都没搜索到。反编译Microsoft.AspNetCore.Server.Kestrel.Core.dll只找到了一样继承自ReadOnlyStream的FrameRequestStream

HttpRequestStream类的CanSeek属性返回值为false，不支持屡次读取，因此须要先转换为FileBufferingReadStream。转换过程可参考：BufferingHelper及HttpRequestRewindExtensions。实现代码以下：

public static class HttpRequestRewindExtensions { public static void EnableBuffering(this HttpRequest request, int bufferThreshold, long bufferLimit) { BufferingHelper.EnableRewind(request, bufferThreshold, bufferLimit); } } ​ ​ public static class BufferingHelper { public static HttpRequest EnableRewind(this HttpRequest request, int bufferThreshold = DefaultBufferThreshold, long? bufferLimit = null) { if (request == null) { throw new ArgumentNullException(nameof(request)); } ​ var body = request.Body; if (!body.CanSeek) { var fileStream = new FileBufferingReadStream(body, bufferThreshold, bufferLimit, _getTempDirectory); request.Body = fileStream; request.HttpContext.Response.RegisterForDispose(fileStream); } return request; } }

 

推荐阅读

Logging in ASP.NET Core

ASP.NET Core Middleware

Stream Class