Serilog簡介

與其他許多.NET庫一樣，Serilog還提供了對文件，控制臺等的基本診斷日志記錄。它易于設(shè)置，具有簡潔的API，并且可以在最新的.NET平臺之間移植。

使用和配置、自定義Enricher

由于 serilog 配置信息比較多，避免硬編碼代碼中，我們在 appsetting.jgon 同級目錄中新建一個(gè) serilogsetting.json 的日志配置文件，簡單內(nèi)容如下:

{
    "Serilog": {
        "Using": [ "Serilog.Sinks.Console", "Serilog.Sinks.Seq" ],
        "MinimumLevel": {
            "Default": "Information",
            "Override": {
                "System": "Error",
                "Microsoft": "Error"
            }
        },
        "WriteTo": [
            {
                "Name": "Console"
            },
            {
                "Name": "Seq",
                "Args": {
                    "serverUrl": "http://localhost:5341/",
                    "apiKey": "L2on8gpgjose5uldhdch"
                }
            }
        ]
    }
}

更多配置內(nèi)容請參考：serilog wiki 文檔

接下來，在 Program.cs 中添加一個(gè)方法，初始化這些配置，然后重寫下構(gòu)建主機(jī)的代碼：

public class Program
{
    public static int Main(string[] args)
    {
        var logConfig = GetLogConfig();
        Log.Logger = new LoggerConfiguration()
                     .ReadFrom.Configuration(logConfig)
                     .Enrich.FormLogContext()
                     .CreateLogger(); 
        try
        {
            // web host 初始化
            var host = BuildWebHost(args);
            host.Run();
            return 0;
        }
        catch(Exception e)
        {
            Log.Fatal(ex, "{ApplicationContext} 出現(xiàn)錯(cuò)誤:{messsage} !", AppName, ex.Message);
            return 1;
        }
        finally
        {
            Log.CloseAndFlush();
        }
    }
    
    /// <summary>
    /// 讀取日志配置
    /// </summary>
    /// <returns></returns>
    private static IConfiguration GetLogConfig()
    {
        var builder = new ConfigurationBuilder()
                      .AddJsonFile("serilogsetting.json", optional: false, reloadOnChange: true);
        return builder.Build();
    
    }
}

然后，添加一個(gè)自定義Enircher,用來記錄HttpContext，的數(shù)據(jù)。_enrichAction則可以自定義，默認(rèn)記錄ip，請求路徑，請求方法，和返回響應(yīng)碼：

public class HttpContextEnricher:ILogEventEnricher
{
    private readonly IServiceProvider _serviceProvider;
    private readonly Action<LogEvent, ILogEventPropertyFactory, HttpContext> _enrichAction;
    
    public HttpContextEnricher(IServiceProvider serviceProvider) : this(serviceProvider, null)
    {}
      
    public HttpContextEnricher(IServiceProvider serviceProvider, Action<LogEvent, ILogEventPropertyFactory, HttpContext> enrichAction)
    {
        _serviceProvider = serviceProvider;
        if (enrichAction == null)
        {
            _enrichAction = (logEvent, propertyFactory, httpContext) =>{
                var x_forwarded_for = new StringValues();
                if (httpContext.Request.Headers.ContainsKey("X-Forwarded-For"))
                {
                   x_forwarded_for = httpContext.Request.Headers["X-Forwarded-For"];
                }
                logEvent.AddPropertyIfAbsent(propertyFactory.CreateProperty("client_ip", JsonConvert.SerializeObject(x_forwarded_for)));
                logEvent.AddPropertyIfAbsent(propertyFactory.CreateProperty("request_path", httpContext.Request.Path));
                logEvent.AddPropertyIfAbsent(propertyFactory.CreateProperty("request_method", httpContext.Request.Method));
                 if (httpContext.Response.HasStarted)
                 {
                     logEvent.AddPropertyIfAbsent(propertyFactory.CreateProperty("response_status", httpContext.Response.StatusCode));
                 }
            }
        }else{
            _enrichAction = enrichAction;
        }
    }
    
    
    public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
    {
        var httpContext = _serviceProvider.GetService<IHttpContextAccessor>()?.HttpContext;
         if (null != httpContext){
             _enrichAction.Invoke(logEvent, propertyFactory, httpContext);
         }
    }
    
}

現(xiàn)在，我們添加了一個(gè)記錄HttpContext的Enricher，但是怎么用起來呢，怎么添加到日志對象中呢。就要靠asp.net core的中間件了。新建一個(gè)HttpContextLogMiddleware中間件：

public class HttpContextLogMiddleware
{
    private readonly RequestDelegate _next;

    public HttpContextLogMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        var serviceProvider = context.RequestServices;
        // 將我們自定義的Enricher添加到LogContext中。
        // LogContext功能很強(qiáng)大，可以動(dòng)態(tài)添加屬性，具體使用介紹，參見官方wiki文檔
        using (LogContext.Push(new HttpContextEnricher(serviceProvider)))
        {
            await _next(context);
        }
    }
}

// 使用擴(kuò)展方法形式注入中間件
public static IApplicationBuilder UseHttpContextLog(
    this IApplicationBuilder builder)
{
    return builder.UseMiddleware<HttpContextLogMiddleware>();
}

這樣，我們就建立了一個(gè)中間件，接下來在Startup.cs的Configure方法中app.UseHttpContextLog();即可。

此處需要注意中間件的順序，參見官方ASP.NET CORE的中間件介紹

這樣，我們就添加了一個(gè)自定義的Enricher來記錄請求的上下文信息。啟動(dòng)應(yīng)用程序，看下輸出結(jié)果：

image