Adding app settings to existing Function App creates a new storage account

Creating a new storage account is an unintended consequence of calling

functionApp.Update()
.WithAppSetting("key", "value")
.Apply();

This also causes the currently deployed functions to be lost since the function app is now pointing at a new storage account.

The offending code is in FunctionAppImpl.cs Line 163-166

I think the root cause of this issue is that the currentStorageAccount is never populated with the actual storage account that is associated with the function app

[m-mertz]

There’s a simple workaround for app settings, and possibly other properties that are inherited from web apps. This works because a Function App is just a special Web App, so we can use those methods instead:

IWebApp app = await azure.WebApps.GetByResourceGroupAsync(resourceGroup, functionAppName).ConfigureAwait(false);
await app.Update().WithAppSetting("testsetting", "value").ApplyAsync().ConfigureAwait(false);

Interestingly enough, the WebApp.List* methods don’t show function apps, but they can be retrieved through the Get* methods.

[weidongxu-microsoft]

Fixed by https://github.com/Azure/azure-libraries-for-net/pull/761