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iot-hub-howto-file-upload-python.md

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title Upload files from devices to Azure IoT Hub (Python)
titleSuffix Azure IoT Hub
description How to upload files from a device to the cloud using Azure IoT device SDK for Python. Uploaded files are stored in an Azure storage blob container.
author SoniaLopezBravo
ms.author sonialopez
ms.service azure-iot-hub
ms.devlang python
ms.topic include
ms.date 12/12/2024
ms.custom
mqtt
devx-track-python
py-fresh-zinc
sfi-ropc-nochange

Install packages

The azure-iot-device library must be installed before calling any related code.

pip install azure-iot-device

The azure.storage.blob package is used to perform the file upload.

pip install azure.storage.blob

Upload file from a device application

This section describes how to upload a file from a device to an IoT hub using the IoTHubDeviceClient class from the Azure IoT SDK for Python.

Import libraries

import os
from azure.iot.device import IoTHubDeviceClient
from azure.core.exceptions import AzureError
from azure.storage.blob import BlobClient

Connect a device to IoT Hub

A device app can authenticate with IoT Hub using the following methods:

  • X.509 certificate
  • Shared access key

Authenticate using an X.509 certificate

[!INCLUDE iot-hub-howto-auth-device-cert-python]

Authenticate using a shared access key

To connect a device to IoT Hub:

  1. Call create_from_connection_string to add the device primary connection string.
  2. Call connect to connect the device client.

For example:

# Add your IoT hub primary connection string
CONNECTION_STRING = "{Device primary connection string}"
device_client = IoTHubDeviceClient.create_from_connection_string(CONNECTION_STRING)

# Connect the client
device_client.connect()

Get Blob Storage information

Call get_storage_info_for_blob to get information from an IoT hub about a linked Azure Storage account. This information includes the hostname, container name, blob name, and a SAS token. The get_storage_info_for_blob method also returns a correlation_id, which is used in the notify_blob_upload_status method. The correlation_id is IoT Hub's way of marking which Blob you're working on.

# Get the storage info for the blob
PATH_TO_FILE = "{Full path to local file}"
blob_name = os.path.basename(PATH_TO_FILE)
blob_info = device_client.get_storage_info_for_blob(blob_name)

Upload a file into Blob Storage

To upload a file into Blob Storage:

  1. Use from_blob_url to create a BlobClient object from a blob URL.
  2. Call upload_blob to upload the file into the Blob Storage.

This example parses the blob_info structure to create a URL that it uses to initialize an BlobClient. Then it calls upload_blob to upload the file into Blob Storage.

try:
    sas_url = "https://{}/{}/{}{}".format(
        blob_info["hostName"],
        blob_info["containerName"],
        blob_info["blobName"],
        blob_info["sasToken"]
    )

    print("\nUploading file: {} to Azure Storage as blob: {} in container {}\n".format(file_name, blob_info["blobName"], blob_info["containerName"]))

    # Upload the specified file
    with BlobClient.from_blob_url(sas_url) as blob_client:
        with open(file_name, "rb") as f:
            result = blob_client.upload_blob(f, overwrite=True)
            return (True, result)

except FileNotFoundError as ex:
    # catch file not found and add an HTTP status code to return in notification to IoT hub
    ex.status_code = 404
    return (False, ex)

except AzureError as ex:
    # catch Azure errors that might result from the upload operation
    return (False, ex)

Notify IoT hub of upload status

Use notify_blob_upload_status to notify IoT hub of the status of the Blob Storage operation. Pass the correlation_id obtained by the get_storage_info_for_blob method. The correlation_id is used by IoT hub to notify any service that might be listening for a notification regarding the status of the file upload task.

This example notifies IoT hub of a successful file upload:

device_client.notify_blob_upload_status(storage_info["correlationId"], True, 200, "OK: {}".format(PATH_TO_FILE)

Shut down the device client

Shut down the client. Once this method is called, any attempt at further client calls result in a ClientError being raised.

device_client.shutdown()

SDK file upload samples

The SDK includes two file upload samples: