ASP.NET Core中使用Graylog记录日志
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() }; // 若将该中间件做为第一个请求管道中的第一个中间件进行注册 // 那么在此处就可以进行全局异常处理 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); } // 需要使用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> /// 需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，因为它封装了过多不需要的东西 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作为配置文件 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(); } }
以上日志记录了如下几个方面：
-
日志信息Id
-
请求来源
-
请求基础信息
采用类似HTTP请求行格式，即：
HttpMethod RequestUrl ResponseStatusCode，如：GET http://localhost 200 -
入参
-
接口耗时
-
若发生异常，则记录异常信息
HttpRequestStream vs FileBufferingReadStream
GET请求参数都体现在Url中了，这里讲述如何获取POST请求的参数。
通常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上可以看到，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只找到了同样继承自ReadOnlyStream的FrameRequestStream
HttpRequestStream类的CanSeek属性返回值为false，不支持多次读取，所以需要先转换为FileBufferingReadStream。转换过程可参考：BufferingHelper及HttpRequestRewindExtensions。实现代码如下：
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; } }
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