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

namespace Microsoft.eShopOnContainers.Services.Catalog.API;

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public IServiceProvider ConfigureServices(IServiceCollection services)
    {
        services.AddAppInsight(Configuration)
            .AddGrpc().Services
            .AddCustomMVC(Configuration)
            .AddCustomDbContext(Configuration)
            .AddCustomOptions(Configuration)
            .AddIntegrationServices(Configuration)
            .AddEventBus(Configuration)
            .AddSwagger(Configuration)
            .AddCustomHealthCheck(Configuration);

        var container = new ContainerBuilder();
        container.Populate(services);

        return new AutofacServiceProvider(container.Build());
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILoggerFactory loggerFactory)
    {
        //Configure logs

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

        var pathBase = Configuration["PATH_BASE"];

        if (!string.IsNullOrEmpty(pathBase))
        {
            loggerFactory.CreateLogger<Startup>().LogDebug("Using PATH BASE '{pathBase}'", pathBase);
            app.UsePathBase(pathBase);
        }

        app.UseSwagger()
            .UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint($"{ (!string.IsNullOrEmpty(pathBase) ? pathBase : string.Empty) }/swagger/v1/swagger.json", "Catalog.API V1");
            });

        app.UseRouting();
        app.UseCors("CorsPolicy");
        app.UseEndpoints(endpoints =>
        {
            endpoints.MapDefaultControllerRoute();
            endpoints.MapControllers();
            endpoints.MapGet("/_proto/", async ctx =>
            {
                ctx.Response.ContentType = "text/plain";
                using var fs = new FileStream(Path.Combine(env.ContentRootPath, "Proto", "catalog.proto"), FileMode.Open, FileAccess.Read);
                using var sr = new StreamReader(fs);
                while (!sr.EndOfStream)
                {
                    var line = await sr.ReadLineAsync();
                    if (line != "/* >>" || line != "<< */")
                    {
                        await ctx.Response.WriteAsync(line);
                    }
                }
            });
            endpoints.MapGrpcService<CatalogService>();
            endpoints.MapHealthChecks("/hc", new HealthCheckOptions()
            {
                Predicate = _ => true,
                ResponseWriter = UIResponseWriter.WriteHealthCheckUIResponse
            });
            endpoints.MapHealthChecks("/liveness", new HealthCheckOptions
            {
                Predicate = r => r.Name.Contains("self")
            });
        });

        ConfigureEventBus(app);
    }

    protected virtual void ConfigureEventBus(IApplicationBuilder app)
    {
        var eventBus = app.ApplicationServices.GetRequiredService<IEventBus>();
        eventBus.Subscribe<OrderStatusChangedToAwaitingValidationIntegrationEvent, OrderStatusChangedToAwaitingValidationIntegrationEventHandler>();
        eventBus.Subscribe<OrderStatusChangedToPaidIntegrationEvent, OrderStatusChangedToPaidIntegrationEventHandler>();
    }
}

public static class CustomExtensionMethods
{
    public static IServiceCollection AddAppInsight(this IServiceCollection services, IConfiguration configuration)
    {
        services.AddApplicationInsightsTelemetry(configuration);
        services.AddApplicationInsightsKubernetesEnricher();

        return services;
    }

    public static IServiceCollection AddCustomMVC(this IServiceCollection services, IConfiguration configuration)
    {
        services.AddControllers(options =>
        {
            options.Filters.Add(typeof(HttpGlobalExceptionFilter));
        })
        .AddJsonOptions(options => options.JsonSerializerOptions.WriteIndented = true);

        services.AddCors(options =>
        {
            options.AddPolicy("CorsPolicy",
                builder => builder
                .SetIsOriginAllowed((host) => true)
                .AllowAnyMethod()
                .AllowAnyHeader()
                .AllowCredentials());
        });

        return services;
    }

    public static IServiceCollection AddCustomHealthCheck(this IServiceCollection services, IConfiguration configuration)
    {
        var accountName = configuration.GetValue<string>("AzureStorageAccountName");
        var accountKey = configuration.GetValue<string>("AzureStorageAccountKey");

        var hcBuilder = services.AddHealthChecks();

        hcBuilder
            .AddCheck("self", () => HealthCheckResult.Healthy())
            .AddSqlServer(
                configuration["ConnectionString"],
                name: "CatalogDB-check",
                tags: new string[] { "catalogdb" });

        if (!string.IsNullOrEmpty(accountName) && !string.IsNullOrEmpty(accountKey))
        {
            hcBuilder
                .AddAzureBlobStorage(
                    $"DefaultEndpointsProtocol=https;AccountName={accountName};AccountKey={accountKey};EndpointSuffix=core.windows.net",
                    name: "catalog-storage-check",
                    tags: new string[] { "catalogstorage" });
        }

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

        return services;
    }

    public static IServiceCollection AddCustomDbContext(this IServiceCollection services, IConfiguration configuration)
    {
        services.AddEntityFrameworkSqlServer()
            .AddDbContext<CatalogContext>(options =>
        {
            options.UseSqlServer(configuration["ConnectionString"],
                                    sqlServerOptionsAction: sqlOptions =>
                                    {
                                        sqlOptions.MigrationsAssembly(typeof(Startup).GetTypeInfo().Assembly.GetName().Name);
                                        //Configuring Connection Resiliency: https://docs.microsoft.com/en-us/ef/core/miscellaneous/connection-resiliency 
                                        sqlOptions.EnableRetryOnFailure(maxRetryCount: 15, maxRetryDelay: TimeSpan.FromSeconds(30), errorNumbersToAdd: null);
                                    });
        });

        services.AddDbContext<IntegrationEventLogContext>(options =>
        {
            options.UseSqlServer(configuration["ConnectionString"],
                                    sqlServerOptionsAction: sqlOptions =>
                                    {
                                        sqlOptions.MigrationsAssembly(typeof(Startup).GetTypeInfo().Assembly.GetName().Name);
                                        //Configuring Connection Resiliency: https://docs.microsoft.com/en-us/ef/core/miscellaneous/connection-resiliency 
                                        sqlOptions.EnableRetryOnFailure(maxRetryCount: 15, maxRetryDelay: TimeSpan.FromSeconds(30), errorNumbersToAdd: null);
                                    });
        });

        return services;
    }

    public static IServiceCollection AddCustomOptions(this IServiceCollection services, IConfiguration configuration)
    {
        services.Configure<CatalogSettings>(configuration);
        services.Configure<ApiBehaviorOptions>(options =>
        {
            options.InvalidModelStateResponseFactory = context =>
            {
                var problemDetails = new ValidationProblemDetails(context.ModelState)
                {
                    Instance = context.HttpContext.Request.Path,
                    Status = StatusCodes.Status400BadRequest,
                    Detail = "Please refer to the errors property for additional details."
                };

                return new BadRequestObjectResult(problemDetails)
                {
                    ContentTypes = { "application/problem+json", "application/problem+xml" }
                };
            };
        });

        return services;
    }

    public static IServiceCollection AddSwagger(this IServiceCollection services, IConfiguration configuration)
    {
        services.AddSwaggerGen(options =>
        {            
            options.SwaggerDoc("v1", new OpenApiInfo
            {
                Title = "eShopOnContainers - Catalog HTTP API",
                Version = "v1",
                Description = "The Catalog Microservice HTTP API. This is a Data-Driven/CRUD microservice sample"
            });
        });

        return services;

    }

    public static IServiceCollection AddIntegrationServices(this IServiceCollection services, IConfiguration configuration)
    {
        services.AddTransient<Func<DbConnection, IIntegrationEventLogService>>(
            sp => (DbConnection c) => new IntegrationEventLogService(c));

        services.AddTransient<ICatalogIntegrationEventService, CatalogIntegrationEventService>();

        if (configuration.GetValue<bool>("AzureServiceBusEnabled"))
        {
            services.AddSingleton<IServiceBusPersisterConnection>(sp =>
            {
                var settings = sp.GetRequiredService<IOptions<CatalogSettings>>().Value;
                var serviceBusConnection = settings.EventBusConnection;

                return new DefaultServiceBusPersisterConnection(serviceBusConnection);
            });
        }
        else
        {
            services.AddSingleton<IRabbitMQPersistentConnection>(sp =>
            {
                var settings = sp.GetRequiredService<IOptions<CatalogSettings>>().Value;
                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);
            });
        }

        return services;
    }

    public static IServiceCollection AddEventBus(this IServiceCollection services, IConfiguration configuration)
    {
        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>();
                string subscriptionName = configuration["SubscriptionClientName"];

                return new EventBusServiceBus(serviceBusPersisterConnection, logger,
                    eventBusSubcriptionsManager, iLifetimeScope, subscriptionName);
            });

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

        return services;
    }
}