ASP.NET Core MVCでSerilogを使う

appsettings.json

{
	"Serilog": {
		"Using": [
			"Serilog.Sinks.File",
			"Serilog.Formatting.Compact"
		],
		"WriteTo": [
			{
				"Name": "File",
				"Args": {
					"formatter": "Serilog.Formatting.Compact.CompactJsonFormatter, Serilog.Formatting.Compact",
					"path": ".\\log\\webapp.txt",
					"restrictedToMinimumLevel": "Information",
					"rollingInterval": "Day"
				}
			}
		]
	}
}

HomeController.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;

namespace WebApp.Controllers {
	public class HomeController : Controller {
		private readonly ILogger _logger;

		public HomeController(ILogger<HomeController> logger) {
			_logger = logger;
		}

		public IActionResult Index() {
			// ログを出力
			_logger.LogInformation(
				"Log {@param}",
				new { controller = "Home", action = "Index" });

			return Content("Home.Index");
		}
	}
}

Program.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;
using Serilog;
using Serilog.Events;
using Serilog.Formatting.Compact;

namespace WebApp {
	public class Program {
		public static void Main(string[] args) {
			// appsettings.jsonを読み込む準備
			var config = new ConfigurationBuilder()
				.SetBasePath(Directory.GetCurrentDirectory())
				.AddJsonFile("appsettings.json")
				.Build();

			// ロガーを構築する
			Log.Logger = new LoggerConfiguration()
				.ReadFrom.Configuration(config)
				.CreateLogger();

			/*
			// ロガーを構築する
			Log.Logger = new LoggerConfiguration()
				// ファイルに書き込む
				.WriteTo.File(
					// JSON形式で出力
					formatter: new CompactJsonFormatter(),
					path: @".\log\webapp.txt",
					restrictedToMinimumLevel: LogEventLevel.Information,
					// 日付ごとに新しいファイルを作る
					rollingInterval: RollingInterval.Day)
				.CreateLogger();
			*/

			try {
				Log.Information("Starting Web Host");

				CreateWebHostBuilder(args)
					.Build()
					.Run();
			} catch (Exception exception) {
				Log.Fatal(exception, "Host terminated unexpectedly");
			} finally {
				Log.CloseAndFlush();
			}
		}

		public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
			WebHost.CreateDefaultBuilder(args)
				.UseStartup<Startup>()
				// ログプロバイダーとしてSerilogを使う
				.UseSerilog();
	}
}