Add troubleshooting for name in use.

docs/index.yml

@@ -205,6 +205,9 @@ conceptualContent:
  - itemType: how-to-guide
  text: Untrusted localhost certificate
  url: troubleshooting/untrusted-localhost-certificate.md
+ - itemType: how-to-guide
+ text: The specified name is already in use
+ url: troubleshooting/name-is-already-in-use.md
  - itemType: reference
  text: Ask questions on Discord
  url: https://aka.ms/aspire/discord

docs/toc.yml

@@ -233,6 +233,8 @@ items:
  href: troubleshooting/untrusted-localhost-certificate.md
  - name: Unable to install .NET Aspire workload
  href: troubleshooting/unable-to-install-workload.md
+ - name: The specified name is already in use
+ href: troubleshooting/name-is-already-in-use.md
  - name: .NET Aspire GitHub repository
  href: https://github.com/dotnet/aspire
  - name: Ask questions on Discord

docs/troubleshooting/name-is-already-in-use.md

@@ -0,0 +1,36 @@
+---
+title: The specified name is already in use
+description: Learn how to troubleshoot the error "The specified name is already in use" when deploying to Azure.
+ms.date: 06/03/2024
+---
+
+# The specified name is already in use
+
+When deploying to Azure initial deployments may fail with an error similar to the following:
+
+> "The specified name is already in use"
+
+This article describes several techniques to avoid this problem.
+
+## Symptoms
+
+When deploying a .NET Aspire app to Azure, the resources in the [app model](../fundamentals/app-host-overview.md#define-the-app-model) are transformed into Azure resources. Some Azure resources have globally scoped names, such as Azure App Configuration, where all instances are in the `[name].azconfig.io` global namespace.
+
+The value of `[name]` is derived from the .NET Aspire resource name, along with random characters based on the resource group name. However, the generated string may exceed the allowable length for the resource name in App Configuration. As a result, some characters are truncated to ensure compliance.
+
+When a conflict occurs in the global namespace, the resource fails to deploy because the combination of `[name]+[truncated hash]` isn't unique enough.
+
+## Possible solutions
+
+One workaround is to avoid using common names like `appconfig` or `storage` for resources. Instead, choose a more meaningful and specific name. This reduces the potential for conflict, but does not completely eliminate it. In such cases, you can use callback methods to set a specific name and avoid using the computed string altogether.
+
+Consider the following example:
+
+```csharp
+var appConfig = builder.AddAzureAppConfiguration(
+ "appConfig",
+ (resource, construct, store) =>
+{
+ store.AssignProperty(p => p.Name, "'noncalculatedname'");
+});
+```