將 ASP.NET Core 的預設 log 輸出至 NLog 或 Serilog

ASP.NET Core 預設會將 WebHost 執行細節透過 stdout 輸出至 console 上，application 的所有動作都一目暸然，這在 debug 時很方便，不過部署在一般的 server 就不會有人時時刻刻去盯著 console，所以需要將 log 內容透過其他方式(e.g. 檔案、db、…etc)紀錄下來備查

過去我個人是比較習慣 NLog 的設定風格，而現在團隊使用 Serilog，所以一併紀錄兩個 log framework 的設定方式

基本環境說明

.NET Core 2.2.101
ASP.NET Core 2.2.0
使用 ASP.NET Core - API 預設範本建立環境
NLog.Web.AspNetCore 4.8.0
Serilog.AspNetCore 2.1.1
Serilog.Sinks.File 4.0.0
Serilog.Settings.Configuration 3.0.1

預設行為：輸出至 console

Hosting environment: Development
Content root path: C:\Users\yowko\source\repos\TestLog\LogTest
Now listening on: https://localhost:5001
Now listening on: http://localhost:5000
Application started. Press Ctrl+C to shut down.
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
      Request starting HTTP/1.1 GET https://localhost:5001/api/values
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[0]
      Executing endpoint 'LogTest.Controllers.ValuesController.Get (LogTest)'
info: Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker[1]
      Route matched with {action = "Get", controller = "Values"}. Executing action LogTest.Controllers.ValuesController.Get (LogTest)
info: Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker[1]
      Executing action method LogTest.Controllers.ValuesController.Get (LogTest) - Validation state: Valid
info: Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker[2]
      Executed action method LogTest.Controllers.ValuesController.Get (LogTest), returned result Microsoft.AspNetCore.Mvc.ObjectResult in 0.3302ms.
info: Microsoft.AspNetCore.Mvc.Infrastructure.ObjectResultExecutor[1]
      Executing ObjectResult, writing value of type 'System.String[]'.
info: Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker[2]
      Executed action LogTest.Controllers.ValuesController.Get (LogTest) in 179.3543ms
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
      Executed endpoint 'LogTest.Controllers.ValuesController.Get (LogTest)'
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[2]
      Request finished in 256.8033ms 200 application/json; charset=utf-8
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
      Request starting HTTP/1.1 GET https://localhost:5001/robots.txt?1552204068727
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[2]
      Request finished in 5.5067ms 404

1default

NLog

安裝 NLog.Web.AspNetCore

Package Manager
```
Install-Package NLog.Web.AspNetCore
```
.NET CLI
```
dotnet add package NLog.Web.AspNetCore
```

建立 nlog.config 檔案

位置為專案根目錄下

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    autoReload="true"
    internalLogLevel="Info"
    internalLogFile="c:\temp\internal-nlog.txt">

<!-- 啟用 ASP.NET Core layout renderers -->
<extensions>
    <add assembly="NLog.Web.AspNetCore"/>
</extensions>

<!-- log 儲存目標 -->
<targets>
    <!-- 儲存目標類型為 "檔案"  -->
    <target xsi:type="File" name="allfile" fileName=".\logs\nlog-all-${shortdate}.log"
            layout="${longdate}|${event-properties:item=EventId_Id}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}" />

    <!-- 儲存目標類型為 "檔案", only own logs.並使用部份 ASP.NET core renderers 的內容 -->
    <target xsi:type="File" name="ownFile-web" fileName=".\logs\nlog-own-${shortdate}.log"
            layout="${longdate}|${event-properties:item=EventId_Id}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}|url: ${aspnet-request-url}|action: ${aspnet-mvc-action}" />
</targets>

<!-- 設定 logger 名稱與 log 儲存目標的對應 -->
<rules>
    <!-- 所有 log -->
    <logger name="*" minlevel="Trace" writeTo="allfile" />

    <!-- 將來自於 Microsoft. assembly 的 Info 以下 (Info,Debug,Trace) log 都排除 (沒有 writeTo 就不會輸出 )-->
    <!-- <logger name="Microsoft.*" maxlevel="Info" final="true" />-->
    <logger name="*" minlevel="Trace" writeTo="ownFile-web" />
</rules>
</nlog>

將 nlog.config 設定輸出
- nlog.config 上按右鍵 –> Properties
- Copy to Output Directory –> Copy always

在 program.cs 中設定啟用 NLog

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>()
            //.ConfigureLogging(logging =>
            //{
            //    //清除其他 logger provide 如預設 console (一經設定 log 就不會在 console 上出現)
            //    logging.ClearProviders();
            //    //設定最低 log 輸出 level
            //    logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
            //})
            .UseNLog();
}

完整 program.cs 內容

using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using NLog.Web;
using Microsoft.Extensions.Logging;

namespace LogTest
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateWebHostBuilder(args).Build().Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                //.ConfigureLogging(logging =>
                //{
                //    //清除其他 logger provide：預設 console
                //    logging.ClearProviders();
                //    //設定最底 log 輸出 level
                //    logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
                //})
                .UseNLog();
    }
}

Serilog

安裝基礎套件 Serilog.AspNetCore

Package Manager
```
Install-Package Serilog.AspNetCore
```
.NET CLI
```
dotnet add package Serilog.AspNetCore
```

視 log 儲存類型安裝套件(以 file 為例)：Serilog.Sinks.File
- Package Manage
```
Install-Package Serilog.Sinks.File
```
- .NET CLI
```
dotnet add package Serilog.Sinks.File
```
安裝 json config 用套件 : Serilog.Settings.Configuration
xml config 需要安裝 Serilog.Settings.AppSettings
- Package Manage
```
Install-Package Serilog.Settings.Configuration
```
- .NET CLI
```
dotnet add package Serilog.Settings.Configuration
```

設定 Serilog 相關參數

設定值寫至 appsettings.json

{
"Serilog": {
    "Using": [  "Serilog.Sinks.File" ],
    "MinimumLevel": "Debug",
    "WriteTo": [
            {
                "Name": "File",
                "Args": {
                "path": ".\\Serilogs\\serilog-configuration-sample.txt",
                "outputTemplate": "{Timestamp:o} [{Level:u3}] ({Application}/{MachineName}/{ThreadId}) {Message}{NewLine}{Exception}",
                "rollingInterval": "Day"
                }
            }
        ]
    }
}

設定啟用 Serilog

Main method

//從 appsettings.json 讀取設定資料
var configuration = new ConfigurationBuilder()
        .SetBasePath(Directory.GetCurrentDirectory())
        .AddJsonFile(path: "appsettings.json", optional: false, reloadOnChange: true)
        .Build();
        
//使用從 appsettings.json 讀取到的內容來設定 logger
Log.Logger = new LoggerConfiguration()
            .ReadFrom.Configuration(configuration)
        .CreateLogger();

CreateWebHostBuilder method

WebHost.CreateDefaultBuilder(args)
        .UseStartup<Startup>()
        //註冊 Serilog
        .UseSerilog();

programs.cs 完整內容

using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Serilog;
using System.IO;

namespace LogTest
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var configuration = new ConfigurationBuilder()
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddJsonFile(path: "appsettings.json", optional: false, reloadOnChange: true)
            .Build();

            Log.Logger = new LoggerConfiguration()
                .ReadFrom.Configuration(configuration)
            .CreateLogger();


            CreateWebHostBuilder(args).Build().Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .UseSerilog();
    }
}

心得

NLog 有點像過去的 .NET Framework 中的 System.Web ：功能齊全，只要一經引用幾乎沒什麼做不到的;Serilog 則像 .NET Core，多數功能都能滿足，但功能拆分細微，需要什麼就單獨安裝、升級

兩者相較下 NLog 感覺是相對直覺、或許該說是習慣，但就文件的完整性來說 NLog 則是佔絕對優勢，同樣的功能 NLog 可以直接從 wiki 上找到設定方式，但 Serilog 就得要東翻西找，加上還參雜了不同版本的 ASP.NET Core 內容造成無法馬上辨別出是否為正確做法

整個 Serilog 在使用的概念上與文件是比較接近 .NET Core，好處、壞處都很像XD

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