AWS Lambda函数中的依赖注入( .Net Core2.2)

Question

我正在尝试使用.Net Core2.2创建一个AWS lambda函数，方法如下

https://aws.amazon.com/blogs/developer/announcing-amazon-lambda-runtimesupport/

我需要实现依赖注入来注入DBContxt，还有业务层的接口。

由于appraoch建议在这个类中只有静态方法作为lambda函数，我的构造函数注入似乎不起作用，因为唯一执行的方法是lambda函数，我试图创建一个静态构造函数和静态初始化器，但它们都没有执行。

以下是示例代码

using Amazon.Lambda.Core;
using Amazon.Lambda.RuntimeSupport;
using Amazon.Lambda.Serialization.Json;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using System;
using System.Threading.Tasks;

namespace Lambda
{
    public class DoSomething
    {
        // Configuration Service
        public static IConfigurationService ConfigService { get; set; }
        public static IManager Manager { get; set; }

        public static DoSomething()
        {
            Console.WriteLine("Static initializer begin....");
            // Set up Dependency Injection
            var serviceCollection = new ServiceCollection();
            ConfigureServices(serviceCollection);
            var serviceProvider = serviceCollection.BuildServiceProvider();

            // Get Configuration Service from DI system
            ConfigService = serviceProvider.GetService<IConfigurationService>();
            Console.WriteLine("Static initializer done....");
        }
        // Use this ctor from unit tests that can mock IConfigurationService
        public DoSomething(IConfigurationService configService, IManager Manager)
        {
            Console.WriteLine("Constructor being....");
            ConfigService = configService;
            Manager = Manager;
            Console.WriteLine("Constructor done....");
        }
        /// <summary>
        /// The main entry point for the custom runtime.
        /// </summary>
        /// <param name="args"></param>
        private static async Task Main(string[] args)
        {
            Func<ILambdaContext, string> func = Expire;
            using(var handlerWrapper = HandlerWrapper.GetHandlerWrapper(func, new JsonSerializer()))
            using(var bootstrap = new LambdaBootstrap(handlerWrapper))
            {
                Console.WriteLine("Main done 0....");
                await bootstrap.RunAsync();
            }
            Console.WriteLine("Main done....");
        }

        /// <summary>
        /// Lambda function to expire items.
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public static string Expire(ILambdaContext context)
        {
            Console.WriteLine("Expire called....");
            // Get config setting using input as a key
            var temp = Manager.Expire();
            context.Logger.LogLine($"Processing-3 ..... {temp}");
            return temp;
        }

        static void ConfigureServices(IServiceCollection serviceCollection)
        {
            // PostgreSQL Configuration.
            serviceCollection.AddEntityFrameworkNpgsql().AddDbContext<DbContext>(opt =>
                opt.UseNpgsql(ConfigService.GetConfiguration().GetConnectionString("DbConnection"))
                );

            // Register services with DI system
            serviceCollection.AddTransient<IEnvironmentService, EnvironmentService>();
            serviceCollection.AddTransient<IConfigurationService, ConfigurationService>();
            serviceCollection.AddTransient<IRepository, Repository>();
            serviceCollection.AddTransient<IManager, Manager>();
        }
    }
}

Answer 1

我能够使用提及AWS教程和托尼·斯奈德的教程https://blog.tonysneed.com/2018/12/16/add-net-core-di-and-config-goodness-to-aws-lambda-functions/来运行DI，但是从Main方法调用DI初始化，因为它需要是静态的。

public class Function
{
    private static IConfigurationService _configService;
    private static IServiceProvider _serviceProvider;

    private static async Task Main(string[] args)
    {
        // Setup DI
        var serviceCollection = new ServiceCollection();
        ConfigureServices(serviceCollection);
        _serviceProvider = serviceCollection.BuildServiceProvider();

        // Get Configuration Service from DI
        _configService = _serviceProvider.GetService<IConfigurationService>();

        // Setup Lambda
        Func<string, ILambdaContext, string> func = FunctionHandler;
        using (var handlerWrapper = HandlerWrapper.GetHandlerWrapper(func, new JsonSerializer()))
        using (var bootstrap = new LambdaBootstrap(handlerWrapper))
        {
            await bootstrap.RunAsync();
        }
    }

    private static void ConfigureServices(IServiceCollection services)
    {
        // Register services with DI system
        services.AddTransient<IConfigurationService, ConfigurationService>();
        services.AddTransient<IEnvironmentService, EnvironmentService>();

        // DI DBContext
        services.AddDbContext<MyDBContext>(options => options.UseSqlServer(_configService.GetConfiguration().GetConnectionString("MyDBConnection")));

        // Other DI
        services.AddTransient<IMyService, MyService>();
    }

    public static string FunctionHandler(string input, ILambdaContext context)
    {
        var myService = _serviceProvider.GetService<IMyService>();
        return myService.DoSomething(input);
    }
}