如何使用 Microsoft.Extensions.Logging for NLog

2020-10-28

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Log
2020-10-29

.NET 提供了標準化的 Log (Microsoft.Extensions.Logging)，NLog 4.5 的時候支援了結構化日誌，同時也實作標準日誌，由於程式碼已經依賴了標準，引用 NLog 也只是彈指之間的設定，仍然可以使用舊的 NLog.Config。還不知道如何使用標準化日誌請看這裡

開發環境

VS 2019
.NET Framework 4.8
.NLog 4.7.5
Microsoft.Extensions.Logging 3.1.9
Microsoft.Extensions.DependencyInjection 3.1.9

.NET Framework 4.8 or .NET Core 3.1 桌面應用程式

NLog 4.5 之後支援了 .NET Standard

開一個 WInFrom App 、.NET Framework 4.8 專案並安裝以下套件

Install-package Microsoft.Extensions.Logging Install-Package NLog.Extensions.Logging Install-Package NLog.Config Install-Package Microsoft.Extensions.Configuration.Json

NLog 組態設定

NLog.Config 套件裝完就會產生 NLog.config，修改一下檔案

增加兩個 target，檔案和 Console
NLog Provider 本身就內建非同步寫入，<targets async="true">，正好彌補 Microsoft.Extensions.Logging 的 Log 方法沒有支援非同步

<?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"
      xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd"
      autoReload="true"
      throwExceptions="false"
      internalLogLevel="Off" internalLogFile="c:\temp\nlog-internal.log">

  <!-- optional, add some variables
  https://github.com/nlog/NLog/wiki/Configuration-file#variables
  -->
  <variable name="myvar" value="myvalue"/>
  <variable name="generic" value="${longdate}|${level}|${message} |${all-event-properties} ${exception:format=tostring}"/>

  <!--
  See https://github.com/nlog/nlog/wiki/Configuration-file
  for information on customizing logging rules and outputs.
   -->
  <targets async="true">

    <!--
    add your targets here
    See https://github.com/nlog/NLog/wiki/Targets for possible targets.
    See https://github.com/nlog/NLog/wiki/Layout-Renderers for the possible layout renderers.
    -->

    <!--
    Write events to a file with the date in the filename.
    <target xsi:type="File" name="f" fileName="${basedir}/logs/${shortdate}.log"
            layout="${longdate} ${uppercase:${level}} ${message}" />
    -->
    <target xsi:type="File" name="logfile" fileName="${basedir}/logs/${shortdate}.log"
            layout="${generic}" />
    <target xsi:type="Console" name="logconsole"
            layout="${generic}" />
  </targets>

  <rules>
    <!-- add your logging rules here -->

    <!--
    Write all events with minimal level of Debug (So Debug, Info, Warn, Error and Fatal, but not Trace)  to "f"
    <logger name="*" minlevel="Debug" writeTo="f" />
    -->
    <logger name="*" minlevel="Trace" writeTo="logfile,logconsole" />

  </rules>
</nlog>

LoggerFactory.Create

建立 LoggerFactory，下面代碼可以把它搬到靜態類別再實例化它，我就不實作了。

private static readonly ILogger<Form1> Logger;

static Form1()
{
    var factory = LoggerFactory.Create(builder =>
                                       {
                                           builder.AddFilter("Microsoft", LogLevel.Warning)
                                                  .AddFilter("System",           LogLevel.Warning)
                                                  .AddFilter("WindowsFormsApp1", LogLevel.Debug)
                                                  .AddNLog();
                                           ;
                                       });
    Logger = factory.CreateLogger<Form1>();
}

private void button1_Click(object sender, EventArgs e)
{
    var button = (Button) sender;
    var name   = button.Name;
 
    Logger.LogInformation(LogEvent.GenerateItem, "{name} 按鈕被按了", name);
    Logger.LogInformation(LogEvent.UpdateItem,   "執行更新");
    Logger.LogInformation(LogEvent.GenerateItem, "完成");
}

除了輸出到 Console 之外，在 bin 資料夾也有 log 檔案

DI container

安裝以下套件

Install-package Microsoft.Extensions.DependencyInjection

Runner 依賴 ILogger<Runner>

public class Runner
{
    private readonly ILogger<Runner> _logger;
 
    public Runner(ILogger<Runner> logger)
    {
        this._logger = logger;
    }
 
    public void DoAction(string name)
    {
        this._logger.LogInformation(LogEvent.UpdateItem, "Doing hard work! {Action}", name);
    }
}

參考 https://github.com/NLog/NLog/wiki/Getting-started-with-.NET-Core-2---Console-application#31-create-your-runner-class

Form1 依賴 ILogger<Runner>、Runner runner

public partial class Form1 : Form
{
    public ILogger<Form1> Logger { get; set; }
 
    public Runner Runner { get; set; }
 
    public Form1()
    {
        this.InitializeComponent();
    }
 
    public Form1(ILogger<Form1> logger, Runner runner)
    {
        this.InitializeComponent();
        this.Logger = logger;
        this.Runner = runner;
    }
 
    private void button1_Click(object sender, EventArgs e)
    {
        var button = (Button) sender;
        var name   = button.Name;
 
        this.Logger.LogInformation(LogEvent.GenerateItem, "{name} 按鈕被按了", name);
        this.Logger.LogInformation(LogEvent.UpdateItem,   "執行更新");
 
        this.Runner.DoAction(name);
 
        this.Logger.LogInformation(LogEvent.GenerateItem, "完成");
    }
}

設定組態

private static IConfiguration CreateConfig()
{
    var config = new ConfigurationBuilder()
                 .SetBasePath(System.IO.Directory
                                    .GetCurrentDirectory()) //From NuGet Package Microsoft.Extensions.Configuration.Json
                 .AddJsonFile("appsettings.json", true, true)
                 .Build();
    return config;
}

實例化 ServiceProvider，注入 Form1、Runner

private static ServiceProvider CreateServiceProvider(IConfiguration config)
{
    var serviceCollection = new ServiceCollection();
    return serviceCollection.AddTransient<Form1>() // Runner is the custom class
                            .AddTransient<Runner>()
                            .AddLogging(loggingBuilder =>
                                        {
                                            // configure Logging with NLog
                                            loggingBuilder.ClearProviders();
                                            loggingBuilder.SetMinimumLevel(LogLevel.Trace);
                                            loggingBuilder.AddNLog(config);
                                        })
                            .BuildServiceProvider();
}

建立 ServiceProvider 後，取出 Form1，丟給 Application.Run

[STAThread]
private static void Main()
{
    Application.EnableVisualStyles();
    Application.SetCompatibleTextRenderingDefault(false);

    var config = CreateConfig();
    using (var serviceProvider = CreateServiceProvider(config))
    {
        var form = serviceProvider.GetService(typeof(Form1)) as Form;
        Application.Run(form);
    }
}

執行結果如下：

除了輸出到 Console 之外，在 bin 資料夾也有 log 檔案

參考

https://github.com/NLog/NLog/wiki/Getting-started-with-.NET-Core-2---Console-application

ASP.NET Core 3.1

新增一個 ASP.NET Core Web Application -> API 專案，安裝以下套件

Install-package NLog.Web.AspNetCore

手動加入 nlog.config 檔案，輸入以下內容

<?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"
      xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd"
      autoReload="true"
      throwExceptions="false"
      internalLogLevel="Off" internalLogFile="c:\temp\nlog-internal.log">

  <!-- enable asp.net core layout renderers -->
  <extensions>
    <add assembly="NLog.Web.AspNetCore"/>
  </extensions>

  <!-- optional, add some variables
  https://github.com/nlog/NLog/wiki/Configuration-file#variables
  -->
  <variable name="myvar" value="myvalue"/>
  <variable name="generic" value="${longdate}|${event-properties:item=EventId_Id}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}"/>
  <!--<variable name="generic" value="${longdate}|${level}|${message} |${all-event-properties} ${exception:format=tostring}"/>-->

  <!--
  See https://github.com/nlog/nlog/wiki/Configuration-file
  for information on customizing logging rules and outputs.
   -->
  <targets async="true">

    <!--
    add your targets here
    See https://github.com/nlog/NLog/wiki/Targets for possible targets.
    See https://github.com/nlog/NLog/wiki/Layout-Renderers for the possible layout renderers.
    -->

    <!--
    Write events to a file with the date in the filename.
    <target xsi:type="File" name="f" fileName="${basedir}/logs/${shortdate}.log"
            layout="${longdate} ${uppercase:${level}} ${message}" />
    -->
    <target xsi:type="File" name="logfile" fileName="${basedir}/logs/${shortdate}.log"
            layout="${generic}" />
    <target xsi:type="Console" name="logconsole"
            layout="${generic}" />

  </targets>

  <rules>
    <!-- add your logging rules here -->

    <!--
    Write all events with minimal level of Debug (So Debug, Info, Warn, Error and Fatal, but not Trace)  to "f"
    <logger name="*" minlevel="Debug" writeTo="f" />
    -->
    <logger name="*" minlevel="Trace" writeTo="logfile,logconsole" />

  </rules>
</nlog>

將檔案複製到輸出位置

清掉預設的 Log Provider，換成 NLog .UseNLog

public class Program
{
    public static IHostBuilder CreateHostBuilder(string[] args)
    {
        return Host.CreateDefaultBuilder(args)
                   .ConfigureWebHostDefaults(webBuilder => { webBuilder.UseStartup<Startup>(); })
                   .ConfigureLogging(logging =>
                                     {
                                         logging.ClearProviders();
                                         logging.SetMinimumLevel(LogLevel.Trace);
                                     })
                   .UseNLog();
    }
 
    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }
}

Controller 建構函數依賴 ILogger<WeatherForecastController>

[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase
{
    private readonly ILogger<WeatherForecastController> _logger;
 
    public WeatherForecastController(ILogger<WeatherForecastController> logger)
    {
        this._logger = logger;
    }
}

在 Action 裡面就可以使用 ILogger<WeatherForecastController> 的實例寫入日誌this._logger.LogInformation

[HttpGet]
public IActionResult Get()
{
    //using (this._logger.BeginScope($"Scope Id:{Guid.NewGuid()}"))
    using (this._logger.BeginScope("Scope Id:{id}", Guid.NewGuid()))
    {
        this._logger.LogInformation(LogEvent.GenerateItem, "開始，訪問 WeatherForecast api");
        this._logger.LogInformation(LogEvent.TestItem,     "執行流程");
 
        var random = new Random();
        var result = Enumerable.Range(1, 5).Select(index => new WeatherForecast
                               {
                                   Date         = DateTime.Now.AddDays(index),
                                   TemperatureC = random.Next(-20, 55),
                                   Summary      = Summaries[random.Next(Summaries.Length)]
                               })
                               .ToArray();
 
        this._logger.LogInformation(LogEvent.GenerateItem, "結束流程");
 
        return this.Ok(result);
    }
}

執行結果

經實驗，NLog 沒有支援 BeginScope

NLog 設定相關資源

targets

輸出目標，NLog 官方實作了很多的目標，官方如果找不到可以嘗試到 Nuget 找，比如 NLog.Slack、NLog.Telegram

https://nlog-project.org/config/?tab=targets

layout-renderers

日誌呈現內容，NLog 提供許多的方法讓你不需要寫扣就能取得相關資訊，比如 ${hostname} 取得電腦名稱

https://nlog-project.org/config/?tab=layout-renderers

rule

根據條件寫入目標，例如

logger name 等於 * 任意字串，且 log level 最小等於 Trace，則寫入 logfile,logconsole 兩個 target

Fluent API

NLog 還可以用 Fluent API 語法操作，由於這不是 Microsoft.Extensions.Logging 的標準，所以沒有支援

using NLog.Fluent;

_logger.Info()
       .Message("This is a test fluent message '{0}'.", DateTime.Now.Ticks)
       .Property("Test", "InfoWrite")
       .Write();

NLog configuration with appsettings.json

如果不喜歡 nlog.config 也可以用 appsettings.json，請參考以下連結：
https://github.com/NLog/NLog.Extensions.Logging/wiki/NLog-configuration-with-appsettings.json

通過標準化的 Microsoft.Extensions.Logging 實現日誌紀錄

專案位置

https://github.com/yaochangyu/sample.dotblog/tree/master/Log/Lab.MsLogging.ForNLog

若有謬誤，煩請告知，新手發帖請多包涵

Microsoft MVP Award 2010~2017 C# 第四季
Microsoft MVP Award 2018~2022 .NET

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