一、前言
在上一章节中使用NLog+SEQ+ILogger构建可视化日志，本章基于Serilog来构建可视化日志。Serilog是.NET中一款非常出色的结构化日志的日志库，其与NLog对比在前一章节进行了说明。Serilog项目不仅仅包含核心项目Seirlog，而且还提供了很多接收器Sinks(超过100个)，这些接收器是通过插件的方式来实现将日志写入到各种终端、文件、邮件、数据库或日志服务器。
二、实践
第一步、安装SEQ服务，并创建Serilog所需要的ApiKey。
第二步：创建一个ASP.NET Core的应用，引入相关的包，如下所示。
<ItemGroup><PackageReference Include="Serilog" Version="4.0.0" /><PackageReference Include="Serilog.AspNetCore" Version="8.0.1" /><PackageReference Include="Serilog.Enrichers.Environment" Version="3.0.0" /><PackageReference Include="Serilog.Expressions" Version="5.0.0" /><PackageReference Include="Serilog.Sinks.Async" Version="2.0.0" /><PackageReference Include="Serilog.Sinks.Console" Version="6.0.0" /><PackageReference Include="Serilog.Sinks.Seq" Version="8.0.0" /> </ItemGroup>
上述安装包主要包括Serilog（基础包），Serilog.AspNetCore（ASP.NET Core应用包），Serilog.Enrichers.Environment（将系统环境信息为日志事件属性记录到日志），并且提供丰富的Enrichers记录详细的日志信息，Serilog.Sinks.Async，Serilog.Sinks.Console，Serilog.Sinks.Seq都是Serilog异步记录写入日志文件、写入控制台打印、异步写入Seq等接收器，Serilog提供丰富的接收器。
第三步、完成上述操作，下一步在代码中实现日志的收集、存储、验证查询功能，日志包含一般打印日志、接口请求日志，所以要对ILogger使用一般日志，接口请求日志进行处理，对于一般打印的日志在上一章节介绍Serilog已经实践了（映入安装包、定义Log配置、注入Serilog的服务，然后在代码中使用ILogger记录日志），对于请求日志则要使用中间件对请求进行处理（定义一个过滤器对接口请求Action相关上下文处理、定义一个特性对这个过滤器在Action方法上标记）。
1、注入Serilog服务，定义一个服务扩展类，减少全部代码堆积在Program中，类名称为ServiceCollectionExtensions，并且使用Serilog的Console日志、文件日志、Seq日志存储代码如下。
using Serilog;
using Serilog.Events;
using Serilog.Sinks.SystemConsole.Themes;namespace tqf.serilogSeq.Demo
{public static class ServiceCollectionExtensions{public static IServiceCollection AddConfigSerilog(this IServiceCollection services, IConfiguration configuration){var seqApiKey = configuration["seq:apiKey"].ToString();var seqServerUrl = configuration["seq:serverUrl"].ToString();Log.Logger = new LoggerConfiguration().MinimumLevel.Debug().MinimumLevel.Override("System", Serilog.Events.LogEventLevel.Debug).MinimumLevel.Override("Microsoft", LogEventLevel.Debug).MinimumLevel.Override("Microsoft.AspNetCore", LogEventLevel.Error).MinimumLevel.Override("Microsoft.AspNetCore.Cors.Infrastructure.CorsService", LogEventLevel.Error).MinimumLevel.Override("Microsoft.AspNetCore.Mvc", LogEventLevel.Error).MinimumLevel.Override("Microsoft.AspNetCore.Hosting", LogEventLevel.Error)// 全部日志写入到Console.WriteTo.Async(c=>c.Console(theme:AnsiConsoleTheme.Literate,outputTemplate: "[T] {Timestamp:yyyy-MM-dd HH:mm:ss,fff} {MachineName}{NewLine}[L] [{Level}]{NewLine}[C] [{SourceContext}] {Message:lj}{NewLine}{Exception}{NewLine}"))// Information日志写入到文件.WriteTo.Async(c => c.File(path: "Logs/Information/.txt",rollingInterval: RollingInterval.Day,fileSizeLimitBytes: 1L * 1024 * 1024 * 1024,retainedFileCountLimit: 31,outputTemplate: "[T] {Timestamp:yyyy-MM-dd HH:mm:ss,fff} {MachineName}{NewLine}[L] [{Level}]{NewLine}[C] [{SourceContext}] {Message:lj}{NewLine}{Exception}{NewLine}",restrictedToMinimumLevel: LogEventLevel.Information))// Debug日志写入到文件.WriteTo.Async(c => c.File(path: "Logs/Debug/.txt",rollingInterval: RollingInterval.Day,fileSizeLimitBytes: 1L * 1024 * 1024 * 1024,retainedFileCountLimit: 31,outputTemplate: "[T] {Timestamp:yyyy-MM-dd HH:mm:ss,fff} {MachineName}{NewLine}[L] [{Level}]{NewLine}[C] [{SourceContext}] {Message:lj}{NewLine}{Exception}{NewLine}",restrictedToMinimumLevel: LogEventLevel.Debug))// Warning日志写入到文件.WriteTo.Async(c => c.File(path: "Logs/Warning/.txt",rollingInterval: RollingInterval.Day,fileSizeLimitBytes: 1L * 1024 * 1024 * 1024,retainedFileCountLimit: 31,outputTemplate: "[T] {Timestamp:yyyy-MM-dd HH:mm:ss,fff} {MachineName}{NewLine}[L] [{Level}]{NewLine}[C] [{SourceContext}] {Message:lj}{NewLine}{Exception}{NewLine}",restrictedToMinimumLevel: LogEventLevel.Warning))// Error日志写入到文件.WriteTo.Async(c => c.File(path: "Logs/Error/.txt",rollingInterval: RollingInterval.Day,fileSizeLimitBytes: 1L * 1024 * 1024 * 1024,retainedFileCountLimit: 31,outputTemplate: "[T] {Timestamp:yyyy-MM-dd HH:mm:ss,fff} {MachineName}{NewLine}[L] [{Level}]{NewLine}[C] [{SourceContext}] {Message:lj}{NewLine}{Exception}{NewLine}",restrictedToMinimumLevel: LogEventLevel.Error))// 全部日志写入到Seq.WriteTo.Async(c=>c.Seq(apiKey:seqApiKey,serverUrl:seqServerUrl)).Enrich.FromLogContext().Enrich.WithMachineName()// 过滤请求：/health心跳.Filter.ByExcluding("RequestPath like '/health%'").CreateBootstrapLogger();services.AddSerilog();return services;}}
}
2、启用中间件，定义一个ApplicationBuilder扩展类，减少中间件代码堆积在Program中，类名称ApplicationBuilderExtensions，代码如下。
using Serilog; using Serilog.Events; using System.Net;namespace tqf.serilogSeq.Demo {/// <summary>/// ApplicationBuilder 扩展/// </summary>public static class ApplicationBuilderExtensions{/// <summary>/// 添加使用Serilog请求日志/// </summary>/// <param name="app"></param>/// <returns></returns>public static IApplicationBuilder UseSerilogRequestLogging(this IApplicationBuilder app){//允许body重用app.Use(next => context =>{context.Request.EnableBuffering();return next(context);});// 添加使用Serilog记录请求日志app.UseSerilogRequestLogging(options =>{// 请求日志输出模板options.MessageTemplate = "\n[R] {RequestMethod}={_RequestPath} | Status={StatusCode} | Time={Elapsed}ms\n[R] Req={_RequestBody} | Res={_ResponseBody}";// 发出调试级别事件而不是默认事件，将请求日志记录到:Debug日志options.GetLevel = (httpContext, elapsed, ex) => LogEventLevel.Debug;// 将其他属性附加到请求完成事件，将请求属性附加可以在模板中使用options.EnrichDiagnosticContext = (diagnosticContext, httpContext) =>{diagnosticContext.Set("_RequestPath", WebUtility.UrlDecode(httpContext.Request.Path + httpContext.Request.QueryString));//请求bodyvar requestContent = "";var method = httpContext.Request.Method.ToLower();if (method == "post" || method == "put"){httpContext.Request.Body.Position = 0;var requestReader = new StreamReader(httpContext.Request.Body);requestContent = requestReader.ReadToEnd();}diagnosticContext.Set("_RequestBody", requestContent);diagnosticContext.Set("_Service", AppDomain.CurrentDomain.FriendlyName);};});return app;}} }
3、定义一个Filter类，对Action的请求进行过滤操作，类名称RequestAuditLogFilter，代码如下。
using Microsoft.AspNetCore.Mvc.Filters; using Microsoft.AspNetCore.Mvc; using Serilog; using Newtonsoft.Json;namespace tqf.serilogSeq.Demo {/// <summary>/// 请求过滤器/// </summary>public class RequestAuditLogFilter : IResultFilter{private readonly IDiagnosticContext _diagnosticContext;public RequestAuditLogFilter(IDiagnosticContext diagnosticContext) { _diagnosticContext = diagnosticContext; }public void OnResultExecuted(ResultExecutedContext context){var result = context.Result as ObjectResult;var resultJson = JsonConvert.SerializeObject(result?.Value);_diagnosticContext.Set("_ResponseBody", resultJson);}public void OnResultExecuting(ResultExecutingContext context) { }} }
4、定义一个Attribute，实现过滤器标记在Action方法上，代码如下。
using Microsoft.AspNetCore.Mvc;namespace tqf.serilogSeq.Demo {/// <summary>/// 请求特性，标签要记录请求日志/// </summary>public class RequestAuditLogAttribute : TypeFilterAttribute{public RequestAuditLogAttribute() : base(typeof(RequestAuditLogFilter)) { }}}
5、在Program中使用扩展的ServiceCollection与ApplicationBuilder来注入Serilog的服务，启用Serilog的中间件，代码如下。
using Microsoft.Extensions.Configuration;namespace tqf.serilogSeq.Demo {public class Program{public static void Main(string[] args){var builder = WebApplication.CreateBuilder(args);// Add services to the container. builder.Services.AddControllers();// 使用Serilog记录日志 builder.Services.AddConfigSerilog(configuration: builder.Configuration);var app = builder.Build();// Configure the HTTP request pipeline. app.UseHttpsRedirection();app.UseAuthorization();// 使用Serilog记录请求日志 app.UseSerilogRequestLogging();app.MapControllers();app.Run();}} }
6、在业务代码中使用日志，代码如下，注意注入IDiagnosticContext实例，然后在Action添加定义的特性RequestAuditLog记录请求日志。
using Microsoft.AspNetCore.Mvc; using Serilog;namespace tqf.serilogSeq.Demo.Controllers {/// <summary>/// 控制器/// </summary> [ApiController][Route("[controller]")]public class WeatherForecastController : ControllerBase{private static readonly string[] Summaries = new[]{"Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"};private readonly ILogger<WeatherForecastController> _logger;private readonly IDiagnosticContext _diagnosticContext;public WeatherForecastController(ILogger<WeatherForecastController> logger, IDiagnosticContext diagnosticContext){_logger = logger;_diagnosticContext = diagnosticContext;}[HttpGet("LogInformation")][RequestAuditLog]public string LogInformation(){return "ok";}[HttpGet("LogError")][RequestAuditLog]public string LogError(){int a = 10;int b = 0;int c = a / b;return "ok";}[HttpPost("LogRequest")][RequestAuditLog]public List<string> LogRequest([FromBody] List<string> input){for (int i = 0; i < 10; i++){input.Add(Guid.NewGuid().ToString());}return input;}[HttpGet][RequestAuditLog]public IEnumerable<WeatherForecast> Get(){return Enumerable.Range(1, 5).Select(index => new WeatherForecast{Date = DateOnly.FromDateTime(DateTime.Now.AddDays(index)),TemperatureC = Random.Shared.Next(-20, 55),Summary = Summaries[Random.Shared.Next(Summaries.Length)]}).ToArray();}} }
7、在appsetting中配置上述的Seq的地址与Key信息。
{"Logging": {"LogLevel": {"Default": "Information","Microsoft.AspNetCore": "Warning"}},"Seq": {"apiKey": "GgnrgKNNuwBsP1JHbPLb","serverUrl": "http://localhost:5341"},"AllowedHosts": "*"
}
第四步、校验结果，运行程序，通过查看Console、文件、SEQ是否保存相关日志数据，及其数据格式项。
如上所示，在三个类型的接收器都接受到相关的数据类型和格式信息，很好完成日志记录的功能。
三、总结
通过上述的实践，Serilog+SEQ+ILogger，提供高可扩展、高灵活性的日志记录服务功能，并且通过上述的扩展类，过滤器、特性、配置项的方式，提供一个低代码入侵的思想，对于日志管理真正优化的实现了。
参考：https://www.cnblogs.com/heyangyi/p/18082599，https://www.cnblogs.com/RainFate/p/16869403.html
