Connection strings stored in K8s CSI Volumes are not resolved during function discovery

[kjlimxxxx]

Description

I have a function triggered by Service Bus connection strings.
There is an issue isolated worker process: the connection string stored in container secret storage are not resolved during function discovery, causing the function to fail.

Reproduction Steps

1. Create an isolated Azure function project with a Service Bus trigger.
2. Store the service bus connection string in the file path C:\mnt\secrets-store\ with a file named ServiceBusConnection.
3. DO NOT include the connection string in the local.settings.json file.
4. Update the Program.cs to load the secret:

   var host = new HostBuilder()
       .ConfigureFunctionsWebApplication()
       .ConfigureAppConfiguration((context, config) => {
           config.AddKeyPerFile("/mnt/secrets-store", false);
       })
       .Build();
   
   await host.RunAsync();

5. Ensure the function uses the connection string:

   [Function(nameof(ServiceBus))]
   public async Task Run(
       [ServiceBusTrigger("myqueue", Connection = "ServiceBusConnection")]
       ServiceBusReceivedMessage message,
       ServiceBusMessageActions messageActions)
   {
       _logger.LogInformation("Message ID: {id}", message.MessageId);
       _logger.LogInformation("Message Body: {body}", message.Body);
       _logger.LogInformation("Message Content-Type: {contentType}", message.ContentType);
   
       // Complete the message
       await messageActions.CompleteMessageAsync(message);
   }

6. Start the project.

Expected behavior

The function should start with the resolved connection string.

Actual behavior

Error Message: When the app starts, the following error occurs:

The listener for function 'Functions.ServiceBus' was unable to start. Microsoft.Azure.WebJobs.Extensions.ServiceBus: Service Bus account connection string with name 'ServiceBusConnection' does not exist in the settings. Make sure that it is a defined App Setting.

Regression?

NA

Known Workarounds

NA

Configuration

Which version of .NET is the code running on?
.NET 8

What OS and version, and what distro if applicable?

1. Can be reproducible with Windows 10, x64.
2. Observed the same issue in docker container - Linux

Other information

1. This issue only occurs in the isolated worker process.
2. The in-process model is working fine.