.net - ASP.net : How to log from within CreateHostBuilder()?

Question

我有一个 ASP.net Core 3.1 Web 应用程序。在 Program.cs 类中，我实现了类似这样的 CreateHostBuilder() 静态方法:

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host
        .CreateDefaultBuilder(args)
        .ConfigureAppConfiguration((context, config) =>
        {
            try 
            {
                // do some configuration work that might fail
            }
            catch (Exception ex)
            {
                // how can I write to a log from here?
            }
        })
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });
}

如果在配置应用程序时抛出异常，当我捕获它时如何使用 ILogger 记录它？

Answer 1

微软的“Logging in .NET Core and ASP.NET Core”文档文章说:

Logging during host construction isn't directly supported. However, a separate logger can be used.

他们继续使用 Serilog 给出这个例子:

public static IHostBuilder CreateHostBuilder(string[] args)
{
    var builtConfig = new ConfigurationBuilder()
        .AddJsonFile("appsettings.json")
        .AddCommandLine(args)
        .Build();

    Log.Logger = new LoggerConfiguration()
        .WriteTo.Console()
        .WriteTo.File(builtConfig["Logging:FilePath"])
        .CreateLogger();

    try
    {
        return Host.CreateDefaultBuilder(args)
            .ConfigureServices((context, services) =>
            {
                services.AddRazorPages();
            })
            .ConfigureAppConfiguration((hostingContext, config) =>
            {
                config.AddConfiguration(builtConfig);
            })
            .ConfigureLogging(logging =>
            {   
                logging.AddSerilog();
            })
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
    }
    catch (Exception ex)
    {
        Log.Fatal(ex, "Host builder error");

        throw;
    }
    finally
    {
        Log.CloseAndFlush();
    }
}