配置服务时，如何在Azure Function V3中注入或使用IConfiguration和依赖项注入

Question

通常在a.NET Core项目我将创建一个引导类来配置我的服务以及DI注册命令。这通常是IServiceCollection的扩展方法，我可以在其中调用像这样的方法。addCosmosDbService和包含该方法的静态类中所需的一切都是自包含的。关键是该方法从Startup类中获取一个IConfiguration。

我以前在Azure函数中使用过DI，但还没有遇到这个具体要求。

我正在使用IConfiguration绑定到一个具体的类，该类的属性与我的本地设置匹配。设置。json以及在Azure中部署该功能时的开发/生产应用程序设置。

/// <summary>
/// Holds configuration settings from local.settings.json or application configuration
/// </summary>    
public class CosmosDbClientSettings
{
    public string CosmosDbDatabaseName { get; set; }
    public string CosmosDbCollectionName { get; set; }
    public string CosmosDbAccount { get; set; }
    public string CosmosDbKey { get; set; }
}

public static class BootstrapCosmosDbClient
{
    /// <summary>
    /// Adds a singleton reference for the CosmosDbService with settings obtained by injecting IConfiguration
    /// </summary>
    /// <param name="services"></param>
    /// <param name="configuration"></param>
    /// <returns></returns>
    public static async Task<CosmosDbService> AddCosmosDbServiceAsync(
        this IServiceCollection services,
        IConfiguration configuration)
    {
        CosmosDbClientSettings cosmosDbClientSettings = new CosmosDbClientSettings();
        configuration.Bind(nameof(CosmosDbClientSettings), cosmosDbClientSettings);

        CosmosClientBuilder clientBuilder = new CosmosClientBuilder(cosmosDbClientSettings.CosmosDbAccount, cosmosDbClientSettings.CosmosDbKey);
        CosmosClient client = clientBuilder.WithConnectionModeDirect().Build();
        CosmosDbService cosmosDbService = new CosmosDbService(client, cosmosDbClientSettings.CosmosDbDatabaseName, cosmosDbClientSettings.CosmosDbCollectionName);
        DatabaseResponse database = await client.CreateDatabaseIfNotExistsAsync(cosmosDbClientSettings.CosmosDbDatabaseName);
        await database.Database.CreateContainerIfNotExistsAsync(cosmosDbClientSettings.CosmosDbCollectionName, "/id");

        services.AddSingleton<ICosmosDbService>(cosmosDbService);

        return cosmosDbService;
    }
}

public class Startup : FunctionsStartup
{

    public override async void Configure(IFunctionsHostBuilder builder)
    {
        builder.Services.AddHttpClient();
        await builder.Services.AddCosmosDbServiceAsync(**need IConfiguration reference**); <--where do I get IConfiguration?
    }
}

显然，在启动中为IConfiguration添加了一个私有字段。cs不起作用，因为它需要填充一些东西，我还读到，在IConfiguration中使用DI不是一个好主意。

我还尝试使用这里描述的选项模式，并实现如下：

builder.Services.AddOptions<CosmosDbClientSettings>()
    .Configure<IConfiguration>((settings, configuration) => configuration.Bind(settings));

而这将有助于注入IOptions

关于如何完成这项工作或可能的变通方法的任何建议？我宁愿把所有的配置放在一个地方（引导文件）。




Answer 1

这里有一个我能够想到的例子；它建立了与Azure应用配置的连接，用于集中配置和功能管理。应该能够使用所有DI功能，例如IConfiguration和IOptions

NuGet依赖项

• 安装-打包Microsoft.天青。函数。扩展
• 安装-打包Microsoft.扩展。配置。AzureAppConfiguration
• 安装-打包Microsoft.扩展。配置。用户秘密

Startup.cs

[assembly: FunctionsStartup(typeof(SomeApp.Startup))]

namespace SomeApp
{
    public class Startup : FunctionsStartup
    {
        public IConfigurationRefresher ConfigurationRefresher { get; private set; }

        public override void Configure(IFunctionsHostBuilder hostBuilder) {
            if (ConfigurationRefresher is not null) {
                hostBuilder.Services.AddSingleton(ConfigurationRefresher);
            }
        }
        public override void ConfigureAppConfiguration(IFunctionsConfigurationBuilder configurationBuilder) {
            var hostBuilderContext = configurationBuilder.GetContext();
            var isDevelopment = ("Development" == hostBuilderContext.EnvironmentName);

            if (isDevelopment) {
                configurationBuilder.ConfigurationBuilder
                    .AddJsonFile(Path.Combine(hostBuilderContext.ApplicationRootPath, $"appsettings.{hostBuilderContext.EnvironmentName}.json"), optional: true, reloadOnChange: false)
                    .AddUserSecrets<Startup>(optional: true, reloadOnChange: false);
            }

            var configuration = configurationBuilder.ConfigurationBuilder.Build();
            var applicationConfigurationEndpoint = configuration["APPLICATIONCONFIGURATION_ENDPOINT"];

            if (!string.IsNullOrEmpty(applicationConfigurationEndpoint)) {
                configurationBuilder.ConfigurationBuilder.AddAzureAppConfiguration(appConfigOptions => {
                    var azureCredential = new DefaultAzureCredential(includeInteractiveCredentials: false);

                    appConfigOptions
                        .Connect(new Uri(applicationConfigurationEndpoint), azureCredential)
                        .ConfigureKeyVault(keyVaultOptions => {
                            keyVaultOptions.SetCredential(azureCredential);
                        })
                        .ConfigureRefresh(refreshOptions => {
                            refreshOptions.Register(key: "Application:ConfigurationVersion", label: LabelFilter.Null, refreshAll: true);
                            refreshOptions.SetCacheExpiration(TimeSpan.FromMinutes(3));
                        });

                    ConfigurationRefresher = appConfigOptions.GetRefresher();
                });
            }
        }
    }
}

Answer 2

在我看来，这个关联的例子设计得很糟糕。它鼓励紧密耦合以及异步等待和阻塞调用的混合。

默认情况下，IConfiguration作为启动的一部分添加到服务集合中，因此我建议更改您的设计，以利用延迟的依赖项解析，这样就可以通过内置的IServiceProvider使用工厂委托解析IConfiguration。

public static class BootstrapCosmosDbClient {

    private static event EventHandler initializeDatabase = delegate { };

    public static IServiceCollection AddCosmosDbService(this IServiceCollection services) {

        Func<IServiceProvider, ICosmosDbService> factory = (sp) => {
            //resolve configuration
            IConfiguration configuration = sp.GetService<IConfiguration>();
            //and get the configured settings (Microsoft.Extensions.Configuration.Binder.dll)
            CosmosDbClientSettings cosmosDbClientSettings = configuration.Get<CosmosDbClientSettings>();
            string databaseName = cosmosDbClientSettings.CosmosDbDatabaseName;
            string containerName = cosmosDbClientSettings.CosmosDbCollectionName;
            string account = cosmosDbClientSettings.CosmosDbAccount;
            string key = cosmosDbClientSettings.CosmosDbKey;

            CosmosClientBuilder clientBuilder = new CosmosClientBuilder(account, key);
            CosmosClient client = clientBuilder.WithConnectionModeDirect().Build();
            CosmosDbService cosmosDbService = new CosmosDbService(client, databaseName, containerName);

            //async event handler
            EventHandler handler = null;
            handler = async (sender, args) => {
                initializeDatabase -= handler; //unsubscribe
                DatabaseResponse database = await client.CreateDatabaseIfNotExistsAsync(databaseName);
                await database.Database.CreateContainerIfNotExistsAsync(containerName, "/id");
            };
            initializeDatabase += handler; //subscribe
            initializeDatabase(null, EventArgs.Empty); //raise the event to initialize db

            return cosmosDbService;
        };
        services.AddSingleton<ICosmosDbService>(factory);
        return service;
    }
}

请注意，为避免在非异步事件处理程序中使用async void而采取的方法。

参考Async/Await——异步编程中的最佳实践。

因此，现在可以正确调用Configure。

public class Startup : FunctionsStartup {

    public override void Configure(IFunctionsHostBuilder builder) =>
        builder.Services
            .AddHttpClient()
            .AddCosmosDbService();
}

Answer 3

从微软1.1.0版开始。蔚蓝色的功能。您可以执行以下操作：

public class Startup : FunctionsStartup
{
    public override void Configure(IFunctionsHostBuilder builder)
    {
        var configuration = builder.GetContext().Configuration;
        builder.Services.AddCosmosDbService(configuration);
    }
}

不幸的是，它仍然不支持异步配置，所以您仍然需要阻止等待任务完成，或者使用@Nkosi的答案描述的技巧。