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

using Autofac;
using Autofac.Extensions.DependencyInjection;
using HealthChecks.UI.Client;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Diagnostics.HealthChecks;
using Microsoft.Azure.ServiceBus;
using Microsoft.eShopOnContainers.BuildingBlocks.EventBus;
using Microsoft.eShopOnContainers.BuildingBlocks.EventBus.Abstractions;
using Microsoft.eShopOnContainers.BuildingBlocks.EventBusRabbitMQ;
using Microsoft.eShopOnContainers.BuildingBlocks.EventBusServiceBus;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Diagnostics.HealthChecks;
using Microsoft.Extensions.Logging;
using Payment.API.IntegrationEvents.EventHandling;
using Payment.API.IntegrationEvents.Events;
using RabbitMQ.Client;
using System;

namespace Payment.API
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public IServiceProvider ConfigureServices(IServiceCollection services)
        {
            services.AddCustomHealthCheck(Configuration);
            services.Configure<PaymentSettings>(Configuration);

            RegisterAppInsights(services);

            if (Configuration.GetValue<bool>("AzureServiceBusEnabled"))
            {
                services.AddSingleton<IServiceBusPersisterConnection>(sp =>
                {
                    var serviceBusConnectionString = Configuration["EventBusConnection"];
                    var serviceBusConnection = new ServiceBusConnectionStringBuilder(serviceBusConnectionString);
                    var subscriptionClientName = Configuration["SubscriptionClientName"];

                    return new DefaultServiceBusPersisterConnection(serviceBusConnection, subscriptionClientName);
                });
            }
            else
            {
                services.AddSingleton<IRabbitMQPersistentConnection>(sp =>
                {
                    var logger = sp.GetRequiredService<ILogger<DefaultRabbitMQPersistentConnection>>();
                    var factory = new ConnectionFactory()
                    {
                        HostName = Configuration["EventBusConnection"],
                        DispatchConsumersAsync = true
                    };

                    if (!string.IsNullOrEmpty(Configuration["EventBusUserName"]))
                    {
                        factory.UserName = Configuration["EventBusUserName"];
                    }

                    if (!string.IsNullOrEmpty(Configuration["EventBusPassword"]))
                    {
                        factory.Password = Configuration["EventBusPassword"];
                    }

                    var retryCount = 5;
                    if (!string.IsNullOrEmpty(Configuration["EventBusRetryCount"]))
                    {
                        retryCount = int.Parse(Configuration["EventBusRetryCount"]);
                    }

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

            RegisterEventBus(services);

            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, ILoggerFactory loggerFactory)
        {
            //loggerFactory.AddAzureWebAppDiagnostics();
            //loggerFactory.AddApplicationInsights(app.ApplicationServices, LogLevel.Trace);

            var pathBase = Configuration["PATH_BASE"];
            if (!string.IsNullOrEmpty(pathBase))
            {
                app.UsePathBase(pathBase);
            }

            ConfigureEventBus(app);

            app.UseRouting();
            app.UseEndpoints(endpoints =>
            {
                endpoints.MapHealthChecks("/hc", new HealthCheckOptions()
                {
                    Predicate = _ => true,
                    ResponseWriter = UIResponseWriter.WriteHealthCheckUIResponse
                });
                endpoints.MapHealthChecks("/liveness", new HealthCheckOptions
                {
                    Predicate = r => r.Name.Contains("self")
                });
            });
        }

        private void RegisterAppInsights(IServiceCollection services)
        {
            services.AddApplicationInsightsTelemetry(Configuration);
            services.AddApplicationInsightsKubernetesEnricher();
        }

        private void RegisterEventBus(IServiceCollection services)
        {
            if (Configuration.GetValue<bool>("AzureServiceBusEnabled"))
            {
                services.AddSingleton<IEventBus, EventBusServiceBus>(sp =>
                {
                    var serviceBusPersisterConnection = sp.GetRequiredService<IServiceBusPersisterConnection>();
                    var iLifetimeScope = sp.GetRequiredService<ILifetimeScope>();
                    var logger = sp.GetRequiredService<ILogger<EventBusServiceBus>>();
                    var eventBusSubcriptionsManager = sp.GetRequiredService<IEventBusSubscriptionsManager>();

                    return new EventBusServiceBus(serviceBusPersisterConnection, logger,
                        eventBusSubcriptionsManager, iLifetimeScope);
                });
            }
            else
            {
                services.AddSingleton<IEventBus, EventBusRabbitMQ>(sp =>
                {
                    var subscriptionClientName = Configuration["SubscriptionClientName"];
                    var rabbitMQPersistentConnection = sp.GetRequiredService<IRabbitMQPersistentConnection>();
                    var iLifetimeScope = sp.GetRequiredService<ILifetimeScope>();
                    var logger = sp.GetRequiredService<ILogger<EventBusRabbitMQ>>();
                    var eventBusSubcriptionsManager = sp.GetRequiredService<IEventBusSubscriptionsManager>();

                    var retryCount = 5;
                    if (!string.IsNullOrEmpty(Configuration["EventBusRetryCount"]))
                    {
                        retryCount = int.Parse(Configuration["EventBusRetryCount"]);
                    }

                    return new EventBusRabbitMQ(rabbitMQPersistentConnection, logger, iLifetimeScope, eventBusSubcriptionsManager, subscriptionClientName, retryCount);
                });
            }

            services.AddTransient<OrderStatusChangedToStockConfirmedIntegrationEventHandler>();
            services.AddSingleton<IEventBusSubscriptionsManager, InMemoryEventBusSubscriptionsManager>();
        }

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

    public static class CustomExtensionMethods
    {
        public static IServiceCollection AddCustomHealthCheck(this IServiceCollection services, IConfiguration configuration)
        {
            var hcBuilder = services.AddHealthChecks();

            hcBuilder.AddCheck("self", () => HealthCheckResult.Healthy());

            if (configuration.GetValue<bool>("AzureServiceBusEnabled"))
            {
                hcBuilder
                    .AddAzureServiceBusTopic(
                        configuration["EventBusConnection"],
                        topicName: "eshop_event_bus",
                        name: "payment-servicebus-check",
                        tags: new string[] { "servicebus" });
            }
            else
            {
                hcBuilder
                    .AddRabbitMQ(
                        $"amqp://{configuration["EventBusConnection"]}",
                        name: "payment-rabbitmqbus-check",
                        tags: new string[] { "rabbitmqbus" });
            }

            return services;
        }
    }
}