如何在ASP.NET Core中根据配置条件启用UseIISIntegration

你可以通过两种方式实现根据配置条件调用UseIISIntegration：

方案一：提前手动构建配置 #

先手动加载和CreateDefaultBuilder一致的配置源，拿到配置值后再决定是否调用UseIISIntegration：

// 手动构建配置，匹配CreateDefaultBuilder的默认加载逻辑
var configBuilder = new ConfigurationBuilder()
    .SetBasePath(Directory.GetCurrentDirectory())
    .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
    .AddJsonFile($"appsettings.{Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") ?? "Production"}.json", optional: true)
    .AddEnvironmentVariables()
    .AddCommandLine(args);

var configuration = configBuilder.Build();

var hostBuilder = WebHost
    .CreateDefaultBuilder(args)
    .UseConfiguration(configuration) // 将手动构建的配置传入主机构建器
    .UseKestrel()
    .UseStartup<Startup>();

if (configuration.GetValue<bool?>("appSettings:UseWindowsAuthentication") == true)
{
    hostBuilder.UseIISIntegration();
}

var host = hostBuilder.Build();
await host.RunAsync();

方案二：直接从WebHostBuilder获取已加载的配置 #

WebHost.CreateDefaultBuilder会自动加载默认配置源（appsettings.json、环境变量等），你可以通过GetConfiguration()扩展方法在构建主机前获取配置：

var hostBuilder = WebHost
    .CreateDefaultBuilder(args)
    .UseKestrel()
    .UseStartup<Startup>();

// 从主机构建器中获取已加载的配置
var configuration = hostBuilder.GetConfiguration();
if (configuration.GetValue<bool?>("appSettings:UseWindowsAuthentication") == true)
{
    hostBuilder.UseIISIntegration();
}

var host = hostBuilder.Build();
await host.RunAsync();

第二种方案更简洁，复用了CreateDefaultBuilder的默认配置加载逻辑，无需手动重复配置源。

内容的提问来源于stack exchange，提问作者chester89