Implemented EF Core DB connections resiliency with explicit retries and execution strategy when using multiple DbContexts

src/Services/Catalog/Catalog.API/Controllers/CatalogController.cs

@@ -158,18 +158,26 @@ namespace Microsoft.eShopOnContainers.Services.Catalog.API.Controllers
             //Update current product
             catalogItem = productToUpdate;
 
-            // Achieving atomicity between original Catalog database operation and the IntegrationEventLog thanks to a local transaction
-            using (var transaction = _catalogContext.Database.BeginTransaction())
+            //Use of an EF Core resiliency strategy when using multiple DbContexts within an explicit BeginTransaction():
+            //See: https://docs.microsoft.com/en-us/ef/core/miscellaneous/connection-resiliency
+            var strategy = _catalogContext.Database.CreateExecutionStrategy();
+
+            await strategy.ExecuteAsync(async () =>
             {
+                // Achieving atomicity between original Catalog database operation and the IntegrationEventLog thanks to a local transaction
+                using (var transaction = _catalogContext.Database.BeginTransaction())
+                {
                     _catalogContext.CatalogItems.Update(catalogItem);
                     await _catalogContext.SaveChangesAsync();
 
                     //Save to EventLog only if product price changed
-                    if(raiseProductPriceChangedEvent)
+                    if (raiseProductPriceChangedEvent)
                         await _integrationEventLogService.SaveEventAsync(priceChangedEvent);
 
                     transaction.Commit();
-            }
+                }
+            });
+
 
             //Publish to Event Bus only if product price changed
             if (raiseProductPriceChangedEvent)

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

@@ -13,6 +13,7 @@
     using Microsoft.Extensions.DependencyInjection;
     using Microsoft.Extensions.Logging;
     using Microsoft.Extensions.Options;
+    using System;
     using System.Data.SqlClient;
     using System.Reflection;
 
@@ -39,21 +40,35 @@
 
         public void ConfigureServices(IServiceCollection services)
         {
+            //Using the same SqlConnection for both DbContexts (CatalogContext and IntegrationEventLogContext)
             var sqlConnection = new SqlConnection(Configuration["ConnectionString"]);
 
-            services.AddDbContext<CatalogContext>(c =>
+            services.AddDbContext<CatalogContext>(options =>
             {
-                c.UseSqlServer(sqlConnection);
+                options.UseSqlServer(sqlConnection,
+                                     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: 5, maxRetryDelay: TimeSpan.FromSeconds(30), errorNumbersToAdd: null);
+                                     });
                 // Changing default behavior when client evaluation occurs to throw. 
                 // Default in EF Core would be to log a warning when client evaluation is performed.
-                c.ConfigureWarnings(warnings => warnings.Throw(RelationalEventId.QueryClientEvaluationWarning));
+                options.ConfigureWarnings(warnings => warnings.Throw(RelationalEventId.QueryClientEvaluationWarning));
                 //Check Client vs. Server evaluation: https://docs.microsoft.com/en-us/ef/core/querying/client-eval
             });
 
-            services.AddDbContext<IntegrationEventLogContext>(c =>
+            services.AddDbContext<IntegrationEventLogContext>(options =>
             {
-                c.UseSqlServer(sqlConnection, b => b.MigrationsAssembly("Catalog.API"));               
-                c.ConfigureWarnings(warnings => warnings.Throw(RelationalEventId.QueryClientEvaluationWarning));                
+                options.UseSqlServer(sqlConnection,
+                                     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: 5, maxRetryDelay: TimeSpan.FromSeconds(30), errorNumbersToAdd: null);
+                                     });
+
+                options.ConfigureWarnings(warnings => warnings.Throw(RelationalEventId.QueryClientEvaluationWarning));                
             });
 
             services.Configure<Settings>(Configuration);

src/Services/Ordering/Ordering.API/Startup.cs

@@ -52,10 +52,14 @@
             services.AddEntityFrameworkSqlServer()
                     .AddDbContext<OrderingContext>(options =>
                     {
-                        options.UseSqlServer(Configuration["ConnectionString"],
-                            sqlop => sqlop.MigrationsAssembly(typeof(Startup).GetTypeInfo().Assembly.GetName().Name));
+                    options.UseSqlServer(Configuration["ConnectionString"],
+                        sqlServerOptionsAction: sqlOptions =>
+                        {
+                            sqlOptions.MigrationsAssembly(typeof(Startup).GetTypeInfo().Assembly.GetName().Name);
+                            sqlOptions.EnableRetryOnFailure(maxRetryCount: 5, maxRetryDelay: TimeSpan.FromSeconds(30), errorNumbersToAdd: null);
+                        });                                       
                     },
-                    ServiceLifetime.Scoped  //DbContext is shared across the HTTP request scope (graph of objects started in the HTTP request)
+                    ServiceLifetime.Scoped  //Showing explicitly that the DbContext is shared across the HTTP request scope (graph of objects started in the HTTP request)
                     );
 
             services.AddSwaggerGen();