dotnet6 Serilog範例

目的

在webapi專案下使用serilog套件

建立新專案

選擇ASP.NET Core Web API專案範本，並執行下一步步驟1

設定新的專案

命名你的專案名稱，並選擇專案要存放的位置。步驟2

其他資訊

直接進行下一步步驟3

NuGet加入套件

Serilog.AspNetCore

步驟4

編輯Program.cs檔

在最外層包一個try catch目的是為了捕捉啟動階段的錯誤

using Serilog;
using Serilog.Events;

Log.Logger = new LoggerConfiguration()
    //Serilog要寫入的最低等級為Information
    .MinimumLevel.Information()
    //Microsoft.AspNetCore開頭的類別等極為warning
    .MinimumLevel.Override("Microsoft.AspNetCore", LogEventLevel.Warning)
    //寫log到Logs資料夾的log.txt檔案中，並且以天為單位做檔案分割
    .WriteTo.File("./Logs/log.txt", rollingInterval: RollingInterval.Day)
    .CreateLogger();
try {
  Log.Information("Starting web host");
  var builder = WebApplication.CreateBuilder(args);
  builder.Services.AddControllers();
  builder.Services.AddEndpointsApiExplorer();
  builder.Services.AddSwaggerGen();
  //controller可以使用ILogger介面來寫入log紀錄
  builder.Host.UseSerilog();
  var app = builder.Build();
  // Configure the HTTP request pipeline.
  if (app.Environment.IsDevelopment()) {
    app.UseSwagger();
    app.UseSwaggerUI();
  }
  app.UseHttpsRedirection();
  app.UseAuthorization();
  app.MapControllers();
  app.Run();
  return 0;
} catch (Exception ex) {
  Log.Fatal(ex, "Host terminated unexpectedly");
  return 1;
} finally { Log.CloseAndFlush(); }

範例5-1

編輯WeatherForecastController.cs類別檔

因預設就有注入ILogger，故可以直接使用

因微軟內建的介面ILogger等級區分與Serilog不一樣，故提供對照表格

	ILogger	Serilog
Level 0	Trace	Verbose
Level 1	Debug	Debug
Level 2	Information	Information
Level 3	Warning	Warning
Level 4	Error	Error
Level 5	Critical	Fatal
Level 6	None	Serilog沒有

    private readonly ILogger<WeatherForecastController> _logger;

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

    [HttpGet(Name = "GetWeatherForecast")]
    public IEnumerable<WeatherForecast> Get() {
      //輸出log
      _logger.LogInformation("This is Controller");
      _logger.LogError("Test Error");
      return Enumerable.Range(1, 5).Select(index => new WeatherForecast {
        Date = DateTime.Now.AddDays(index),
        TemperatureC = Random.Shared.Next(-20, 55),
        Summary = Summaries[Random.Shared.Next(Summaries.Length)]
      })
      .ToArray();
    }