From cc9af86f350d6cce5fdd4eefcf59872a2e3f0b8c Mon Sep 17 00:00:00 2001
From: Sumit Ghosh <sumit.ghosh@neudesic.com>
Date: Thu, 14 Oct 2021 16:39:39 +0530
Subject: [PATCH] Included MigrateDbContext method in HostExtensions

---
 .../Catalog.API/Extensions/HostExtensions.cs  | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/src/Services/Catalog/Catalog.API/Extensions/HostExtensions.cs b/src/Services/Catalog/Catalog.API/Extensions/HostExtensions.cs
index 44b7e3d87..8720fa809 100644
--- a/src/Services/Catalog/Catalog.API/Extensions/HostExtensions.cs
+++ b/src/Services/Catalog/Catalog.API/Extensions/HostExtensions.cs
@@ -61,6 +61,58 @@ public static class HostExtensions
         return host;
     }
 
+    public static IWebHost MigrateDbContext<TContext>(this IWebHost host, Action<TContext, IServiceProvider> seeder) where TContext : DbContext
+    {
+        var underK8s = host.IsInKubernetes();
+
+        using (var scope = host.Services.CreateScope())
+        {
+            var services = scope.ServiceProvider;
+
+            var logger = services.GetRequiredService<ILogger<TContext>>();
+
+            var context = services.GetService<TContext>();
+
+            try
+            {
+                logger.LogInformation("Migrating database associated with context {DbContextName}", typeof(TContext).Name);
+
+                if (underK8s)
+                {
+                    InvokeSeeder(seeder, context, services);
+                }
+                else
+                {
+                    var retry = Policy.Handle<SqlException>()
+                            .WaitAndRetry(new TimeSpan[]
+                            {
+                            TimeSpan.FromSeconds(3),
+                            TimeSpan.FromSeconds(5),
+                            TimeSpan.FromSeconds(8),
+                            });
+
+                    //if the sql server container is not created on run docker compose this
+                    //migration can't fail for network related exception. The retry options for DbContext only 
+                    //apply to transient exceptions
+                    // Note that this is NOT applied when running some orchestrators (let the orchestrator to recreate the failing service)
+                    retry.Execute(() => InvokeSeeder(seeder, context, services));
+                }
+
+                logger.LogInformation("Migrated database associated with context {DbContextName}", typeof(TContext).Name);
+            }
+            catch (Exception ex)
+            {
+                logger.LogError(ex, "An error occurred while migrating the database used on context {DbContextName}", typeof(TContext).Name);
+                if (underK8s)
+                {
+                    throw;          // Rethrow under k8s because we rely on k8s to re-run the pod
+                }
+            }
+        }
+
+        return host;
+    }
+
     private static void InvokeSeeder<TContext>(Action<TContext, IServiceProvider> seeder, TContext context, IServiceProvider services)
         where TContext : DbContext
     {