Unable to bulk import devices with Private Storage account - azure

Question

I am working on stress testing for our IoT Usecase.
For testing, I need to create 100 devices.
So, I have developed one azure function to use IoTHubs Import Device feature as per MSFT docs.
When I used, sample code using Public Storage account for Import/Output blob container SAS token.
It worked as per expectation and created devices on IoTHub.
But when I am using same code with Private Storage account, it is sometimes throwing reading error and sometimes it is throwing writing error on blob storage, even if SAS token has all required permissions (Read, Write, Delete, Create, List, Add etc..), and even private storage account is also having DNS configuration available. And for other use, I am able to add/update/delete blobs on the same private storage account.
Only problem I am facing is while calling ImportDevicesAsync method of IoTHub's RegistryManager.
My sample code is as below:
To create devices.txt file and upload it on proper container.
for (int i = deviceIndex; i < deviceCount + deviceIndex; i++)
{
var deviceToAdd = new ExportImportDevice()
{
Id = $"{devicePrefix}{i.ToString().PadLeft(6, '0')}",
ImportMode = importMode == "delete" ? ImportMode.Delete : ImportMode.Create,
Status = DeviceStatus.Enabled,
Authentication = new AuthenticationMechanism()
{
SymmetricKey = new SymmetricKey()
{
PrimaryKey = CryptoKeyGenerator.GenerateKey(32),
SecondaryKey = CryptoKeyGenerator.GenerateKey(32)
}
},
Tags = new TwinCollection(initialTags.SerializeObject())
};
serializedDevices.Add(deviceToAdd.SerializeObject());
}
// Write the list to the blob
StringBuilder sb = new();
serializedDevices.ForEach(serializedDevice => sb.AppendLine(serializedDevice));
Uri uri = new(assetsBlockBlobUrl + "?" + assetsBlobContainerSas);
CloudBlockBlob blob = new(uri);
await blob.DeleteIfExistsAsync();
using (CloudBlobStream stream = await blob.OpenWriteAsync())
{
byte[] bytes = Encoding.UTF8.GetBytes(sb.ToString());
for (var i = 0; i < bytes.Length; i += 500)
{
int length = Math.Min(bytes.Length - i, 500);
await stream.WriteAsync(bytes.AsMemory(i, length));
}
}
To import devices from the same container using registryManager.ImportDeviceAsync method:
RegistryManager registryManager = RegistryManager.CreateFromConnectionString(Environment.GetEnvironmentVariable("iotHubConnectionString"));
JobProperties importJob = await registryManager.ImportDevicesAsync(containerSasUri, containerSasUri);
////Wait until job is finished
while (true)
{
importJob = await registryManager.GetJobAsync(importJob.JobId);
_logger.LogInformation("import job " + importJob.Status);
if (importJob.Status == JobStatus.Completed)
{
return Common.Utils.GetObjectResult(importMode == "delete" ? MessageConstants.SuccessDeletedAsset : MessageConstants.SuccessCreatedAsset);
}
else if (importJob.Status == JobStatus.Failed)
{
return Common.Utils.GetObjectResult(importMode == "delete" ? MessageConstants.DeleteDeviceFail : MessageConstants.CreateDeviceFail);
}
else if (importJob.Status == JobStatus.Cancelled)
{
return Common.Utils.GetObjectResult(importMode == "delete" ? MessageConstants.DeviceDeletionCancel : MessageConstants.DeviceCreationCancel);
}
await Task.Delay(TimeSpan.FromSeconds(5));
}