Adds breaking changes content for Azure SQL Server admin user-assigned managed id.

docs/compatibility/9.3/azure-sql-server-default-uami-admin.md

@@ -0,0 +1,59 @@
+---
+title: "Breaking change - AddAzureSqlServer assigns a dedicated user-assigned managed identity as the administrator"
+description: "Learn about the breaking change in .NET Aspire 9.3 where Azure SQL Server instances are assigned dedicated user managed identities as administrators."
+ms.date: 5/12/2025
+ai-usage: ai-assisted
+ms.custom: https://github.com/dotnet/docs-aspire/issues/3386
+---
+
+# AddAzureSqlServer assigns a dedicated user-assigned managed identity as the administrator
+
+In .NET Aspire 9.3, Azure SQL Server instances are now assigned dedicated user managed identities as administrators. This change resolves issues with overlapping managed identities when using multiple app containers. Additionally, app containers and local users are granted the `db_owner` role for database access.
+
+## Version introduced
+
+.NET Aspire 9.3
+
+## Previous behavior
+
+In Aspire 9.2, each container app was assigned its own managed identity as the administrator. However, when multiple app containers were used, the second container would overwrite the administrator role of the first, causing access issues.
+
+## New behavior
+
+In Aspire 9.3, each Azure SQL Server instance is assigned a dedicated user managed identity as its administrator. App containers using these SQL Server instances are granted the `db_owner` role during deployment. If an application isn't deployed as an app container, the current Entra ID user account is also added as a `db_owner` in the database, enabling data management.
+
+To prevent automatic configuration, the <xref:Aspire.Hosting.ExistingAzureResourceExtensions.AsExisting*> method can be used on the Azure SQL Server resource. Existing instances aren't reconfigured.
+
+## Type of breaking change
+
+This is a [behavioral change](../categories.md#behavioral-change).
+
+## Reason for change
+
+This change resolves a limitation where multiple app containers caused conflicts in administrator assignments for Azure SQL Server instances. It ensures each instance has a dedicated administrator and improves role assignment consistency.
+
+## Recommended action
+
+No recommended action is required if the new behavior aligns with your requirements. However, if you prefer the previous behavior, you can use the `AsExisting` method to prevent automatic configuration of the Azure SQL Server instance. For example:
+
+```csharp
+var builder = DistributedApplication.CreateBuilder();
+
+var existingSqlServerName = builder.AddParameter("existingSqlServerName");
+var existingSqlServerResourceGroup = builder.AddParameter("existingSqlServerResourceGroup");
+
+var sql = builder.AddAzureSqlServer("sql")
+                 .AsExisting(existingSqlServerName, existingSqlServerResourceGroup);
+
+// Use the existing SQL Server using WithReference...
+
+builder.Build().Run();
+```
+
+## Affected APIs
+
+- <xref:Aspire.Hosting.AzureContainerAppContainerExtensions.PublishAsAzureContainerApp``1(Aspire.Hosting.ApplicationModel.IResourceBuilder{``0},System.Action{Aspire.Hosting.Azure.AzureResourceInfrastructure,Azure.Provisioning.AppContainers.ContainerApp})>
+- <xref:Aspire.Hosting.AzureContainerAppExecutableExtensions.PublishAsAzureContainerApp``1(Aspire.Hosting.ApplicationModel.IResourceBuilder{``0},System.Action{Aspire.Hosting.Azure.AzureResourceInfrastructure,Azure.Provisioning.AppContainers.ContainerApp})>
+- <xref:Aspire.Hosting.AzureContainerAppExtensions.AddAzureContainerAppsInfrastructure(Aspire.Hosting.IDistributedApplicationBuilder)>
+- <xref:Aspire.Hosting.AzureContainerAppProjectExtensions.PublishAsAzureContainerApp``1(Aspire.Hosting.ApplicationModel.IResourceBuilder{``0},System.Action{Aspire.Hosting.Azure.AzureResourceInfrastructure,Azure.Provisioning.AppContainers.ContainerApp})>
+- <xref:Aspire.Hosting.SqlServerBuilderExtensions.AddSqlServer(Aspire.Hosting.IDistributedApplicationBuilder,System.String,Aspire.Hosting.ApplicationModel.IResourceBuilder{Aspire.Hosting.ApplicationModel.ParameterResource},System.Nullable{System.Int32})>

docs/compatibility/9.3/index.md

@@ -18,6 +18,7 @@ If you're migrating an app to .NET Aspire 9.3, the breaking changes listed here
 
 | Title | Type of change | Introduced version |
 |--|--|--|
+| [AddAzureSqlServer assigns a dedicated user-assigned managed identity as the administrator](azure-sql-server-default-uami-admin.md) | Behavioral change | 9.3 |
 | [Change the default SKU used for creating a new Azure SQL database](azure-sql-server-default-sku-changes.md) | Behavioral change | 9.3 |
 | [Remove publisher APIs](remove-publisher-apis.md) | Binary incompatible, source incompatible, and behavioral change | 9.3 |
 | [With health checks changes in .NET Aspire 9.3](with-health-checks-changes.md) | Binary and source incompatible | 9.3 |

docs/compatibility/toc.yml

@@ -19,6 +19,8 @@ items:
       href: 9.3/azure-sql-server-default-sku-changes.md
     - name: Removal of publisher APIs
       href: 9.3/remove-publisher-apis.md
+    - name: Azure SQL Server default user-assigned managed identity admin changes
+      href: 9.3/azure-sql-server-default-uami-admin.md
 - name: .NET Aspire 9.2
   expanded: false
   items: