方法是创建一个服务集合扩展类，并在Program.cs中指向这个类，而不是在ConfigureServices中注册该服务。

从KeyVault获取属性时需要解析appsettings.json键的任何代码现在都在工作。对我来说，这似乎很幸运，我只能假设服务扩展知道在启动的第一阶段之后返回并得到任何丢失的密钥。

Program.cs

IHost host = Host.CreateDefaultBuilder(args)
.ConfigureServices(services =>
    var configuration = new ConfigurationBuilder()
            .AddJsonFile("appsettings.json")
            .Build();
    // ------------------------
    // ----- Lite DB START-----
    // ------------------------
    // ----- BAD -----
    // *This doesnt work becuase the keyvault client hasnt started up yet!!!*
    var connectionString = configuration.GetSection("LiteDB").GetValue<string>("Password");
    // Simply returns the native value in app settings, rather than the actual key value stored in Azure KeyVault
    Console.WriteLine(connectionString); 
    // ---------------------------------
    // ----- Solution -----
    // Add the IService Collection Extension, see seperate class further down...
    services.AddDatabase();
    // -----------------------
    // ----- Lite DB END-----
    // -----------------------
    // Repository used for our own logging events throughout the business logic code base.
    services.AddTransient<ILogExtension, LogExtension>();
    // Add the Background Services
    services.AddHostedService<AzureSignalRService>();
.ConfigureAppConfiguration((context, config) => // Azure KeyVault Configuration
    if (context.HostingEnvironment.IsDevelopment() | context.HostingEnvironment.IsProduction())
        // See https://learn.microsoft.com/en-us/aspnet/core/security/key-vault-configuration?view=aspnetcore-6.0
        // See https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/security/key-vault-configuration/samples/3.x/SampleApp/Startup.cs
        var root = config.Build();
        using var x509Store = new X509Store(StoreLocation.CurrentUser);
        x509Store.Open(OpenFlags.ReadOnly);
        var x509Certificate = x509Store.Certificates
        .Find(
            X509FindType.FindByThumbprint,
            root["AzureADCertThumbprint"],
            validOnly: false)
        .OfType<X509Certificate2>()
        .Single();
        config.AddAzureKeyVault(
        new Uri($"https://{root["KeyVaultName"]}.vault.azure.net/"),
        new ClientCertificateCredential(
            root["AzureADDirectoryId"],
            root["AzureADApplicationId"],
            x509Certificate));
.Build();

独立的IServiceCollection类：

internal static class ServiceCollectionDatabaseExtensions
    public static IServiceCollection AddDatabase(this IServiceCollection services)
        var config = services.BuildServiceProvider().GetService<IConfiguration>();
        var password = config!.GetSection("LiteDB").GetValue<string>("Password");
        Console.WriteLine(password); // This now returns the correct key vaue pulled from Azure Key Vault
        var connectionString = "Filename=C:\'database.db;Connection=shared;Password=" + password;
        Console.WriteLine(connectionString);
        services.AddSingleton<ILiteDatabase, LiteDatabase>(x => new LiteDatabase(connectionString));
        // Other services here...
        return services;
}

ConfigureAppConfiguration 运行在 ConfigureServices 之前，因此当您配置服务时，配置已经加载。逻辑上应该是这样的：

IHost host = Host.CreateDefaultBuilder(args)    
.ConfigureAppConfiguration((context, config) =>
  config.AddAzureKeyVault(...);
.ConfigureServices(services =>