Blazor Server でログを出力する

Blazor Server でログを出力する。Windows、Linux どちらへもデプロイ可能。
ソースコードはGitHubで公開しています。

ソースコード構成

ソースコード変更内容を解説

WebApplication1.csproj

・NLog、NLog.Web.AspNetCore Nugetパッケージを追加。


<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net5.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="NLog" Version="4.7.13" />
    <PackageReference Include="NLog.Web.AspNetCore" Version="4.14.0" />
  </ItemGroup>

</Project>

</PropertyGroup>

</ItemGroup>

</Project>

NLog.config

・NLog定義ファイルの fileName=”${basedir}/../log/${shortdate}_LogTest.log” が出力先ファイルのパス。実行フォルダの１つ上の階層にlogフォルダを作成し、 logフォルダ内にログファイルを出力している。パスに含まれるフォルダが無くても自動で作成してくれる。
・minlevel=”Debug” でログ出力レベルを切り替える。
・設置値も Windows/Linux共通。


<?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="/var/aspnet/nlog-internal.log">

	<extensions>
		<add assembly="NLog.Web.AspNetCore" />
	</extensions>

	<variable name="myvar" value="myvalue"/>

	<targets>
		<target xsi:type="File" name="logfile" fileName="${basedir}/../log/${shortdate}LogTest.log"
				layout="${longdate} ${uppercase:${level}} [${threadid}] ${message}"
				encoding="UTF-8" writeBom="true" lineEnding="CRLF" maxArchiveDays="30" />
	</targets>

	<rules>
		<logger name="*" minlevel="Debug" writeTo="logfile" enabled="true" />
	</rules>
</nlog>

<?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="/var/aspnet/nlog-internal.log">

</extensions>

<target xsi:type="File" name="logfile" fileName="${basedir}/../log/${shortdate}LogTest.log"

layout="${longdate} ${uppercase:${level}} [${threadid}] ${message}"

encoding="UTF-8" writeBom="true" lineEnding="CRLF" maxArchiveDays="30" />

</targets>

<rules>

</rules>

</nlog>

Program.cs

・Main()メソッドにアプリ起動ログ（”init main”）を追加。
・CreateHostBuilder()メソッドにNLog機能を追加。


using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using NLog.Web;

namespace WebApplication1
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var logger = NLogBuilder.ConfigureNLog("NLog.config").GetCurrentClassLogger();
            try
            {
                logger.Info("init main");

                CreateHostBuilder(args).Build().Run();

            }
            catch (Exception ex)
            {
                logger.Error(ex, "Stopped program because of exception");
                throw;
            }
            finally
            {
                NLog.LogManager.Shutdown();
            }
        }

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

using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

using Microsoft.AspNetCore.Hosting;

using Microsoft.Extensions.Configuration;

using Microsoft.Extensions.Hosting;

using Microsoft.Extensions.Logging;

using NLog.Web;

namespace WebApplication1

{

public class Program

{

public static void Main(string[] args)

{

var logger = NLogBuilder.ConfigureNLog("NLog.config").GetCurrentClassLogger();

try

{

logger.Info("init main");

CreateHostBuilder(args).Build().Run();

}

catch (Exception ex)

{

logger.Error(ex, "Stopped program because of exception");

throw;

}

finally

{

NLog.LogManager.Shutdown();

}

public static IHostBuilder CreateHostBuilder(string[] args) =>

Host.CreateDefaultBuilder(args)

.ConfigureWebHostDefaults(webBuilder =>

{

webBuilder.UseStartup<Startup>();

})

.ConfigureLogging(logging => {

logging.ClearProviders();

logging.SetMinimumLevel(LogLevel.Trace);

})

.UseNLog();

}

_Imports.razor

Asp.Net Core のログ機能のusingを追加。


@using System.Net.Http
@using Microsoft.AspNetCore.Authorization
@using Microsoft.AspNetCore.Components.Authorization
@using Microsoft.AspNetCore.Components.Forms
@using Microsoft.AspNetCore.Components.Routing
@using Microsoft.AspNetCore.Components.Web
@using Microsoft.AspNetCore.Components.Web.Virtualization
@using Microsoft.Extensions.Logging
@using Microsoft.JSInterop
@using WebApplication1
@using WebApplication1.Shared

@using System.Net.Http

@using Microsoft.AspNetCore.Authorization

@using Microsoft.AspNetCore.Components.Authorization

@using Microsoft.AspNetCore.Components.Forms

@using Microsoft.AspNetCore.Components.Routing

@using Microsoft.AspNetCore.Components.Web

@using Microsoft.AspNetCore.Components.Web.Virtualization

@using Microsoft.Extensions.Logging

@using Microsoft.JSInterop

@using WebApplication1

@using WebApplication1.Shared

Shared/Pages/Counter.razor

・既存の画面にログ出力処理を追加。


@page "/Counter"
@inject ILogger<Counter> _Logger

<h1>Counter</h1>

<p>Current count: @currentCount</p>

<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>

@code {
    private int currentCount = 0;

    private void IncrementCount()
    {
        currentCount++;

        _Logger.LogDebug($"Debug level log write.{currentCount}");

        _Logger.LogInformation($"Information level log write.{currentCount}");

        _Logger.LogWarning($"Warning level log write.{currentCount}");

        _Logger.LogError($"Error level log write.{currentCount}");
    }
}

@page "/Counter"

@inject ILogger<Counter> _Logger

<h1>Counter</h1>

<p>Current count: @currentCount</p>

<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>

@code {

private int currentCount = 0;

private void IncrementCount()

{

currentCount++;

_Logger.LogDebug($"Debug level log write.{currentCount}");

_Logger.LogInformation($"Information level log write.{currentCount}");

_Logger.LogWarning($"Warning level log write.{currentCount}");

_Logger.LogError($"Error level log write.{currentCount}");

}

Visual Studio プロジェクト

今回使った Visual Studio プロジェクトテンプレートは、Blazor Server 5.0 の認証無し、HTTPS無しです。