eShopOnContainers/src/Services/Payment/Payment.API/Startup.cs

using Autofac;
using Autofac.Extensions.DependencyInjection;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using System;
using Microsoft.eShopOnContainers.BuildingBlocks.EventBus.Abstractions;
using Microsoft.eShopOnContainers.BuildingBlocks.EventBusRabbitMQ;
using RabbitMQ.Client;
using Microsoft.eShopOnContainers.BuildingBlocks.EventBus;
using Payment.API.IntegrationEvents.Events;
using Payment.API.IntegrationEvents.EventHandling;

namespace Payment.API
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                .AddEnvironmentVariables();
            Configuration = builder.Build();
        }

        public IConfigurationRoot Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public IServiceProvider ConfigureServices(IServiceCollection services)
        {
            // Add framework services.
            services.AddMvc();
            services.Configure<PaymentSettings>(Configuration);
            services.AddSingleton<IRabbitMQPersistentConnection>(sp =>
            {
                var logger = sp.GetRequiredService<ILogger<DefaultRabbitMQPersistentConnection>>();

                var factory = new ConnectionFactory()
                {
                    HostName = Configuration["EventBusConnection"]
                };

                return new DefaultRabbitMQPersistentConnection(factory, logger);
            });

            RegisterServiceBus(services);

            services.AddSwaggerGen();
            services.ConfigureSwaggerGen(options =>
            {
                options.DescribeAllEnumsAsStrings();
                options.SingleApiVersion(new Swashbuckle.Swagger.Model.Info()
                {
                    Title = "eShopOnContainers - Payment HTTP API",
                    Version = "v1",
                    Description = "The Payment Microservice HTTP API. This is a Data-Driven/CRUD microservice sample",
                    TermsOfService = "Terms Of Service"
                });
            });

            var container = new ContainerBuilder();
            container.Populate(services);
            return new AutofacServiceProvider(container.Build());
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            app.UseMvcWithDefaultRoute();

            app.UseSwagger()
              .UseSwaggerUi();

            ConfigureEventBus(app);
        }

        private void RegisterServiceBus(IServiceCollection services)
        {
            services.AddSingleton<IEventBus, EventBusRabbitMQ>();
            services.AddSingleton<IEventBusSubscriptionsManager, InMemoryEventBusSubscriptionsManager>();

            services.AddTransient<IIntegrationEventHandler<OrderStatusChangedToStockConfirmedIntegrationEvent>, 
                OrderStatusChangedToStockConfirmedIntegrationEventHandler>();
        }

        private void ConfigureEventBus(IApplicationBuilder app)
        {
            var eventBus = app.ApplicationServices.GetRequiredService<IEventBus>();
            eventBus.Subscribe<OrderStatusChangedToStockConfirmedIntegrationEvent, 
                IIntegrationEventHandler<OrderStatusChangedToStockConfirmedIntegrationEvent>>();
        }
    }
}