Microsoft Azure Timer Function not uploading files to blob storage

Question

I am trying to do a timer trigger whereby every 5 minutes, the function will upload a file into my blob storage.

When I run my code locally, it works, but it fails when it is deployed on Azure. Any help will be appreciated.

Main Method

device_client = IoTHubDeviceClient.create_from_connection_string(CONNECTION_STRING)
PATH_TO_FILE = wget.download("link-of-something", out=os.getcwd()) 
device_client.connect()
blob_name = os.path.basename(PATH_TO_FILE)
storage_info = device_client.get_storage_info_for_blob(blob_name)
store_blob(storage_info, PATH_TO_FILE)
device_client.shutdown()

Helper method

def store_blob(blob_info, file_name):
    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)

This is the error log (Edited)

Result: Failure Exception: OSError: [Errno 30] Read-only file system: './nasa_graphics_manual_nhb_1430-2_jan_1976.pdfjo243l48.tmp' Stack: File "/azure-functions-host/workers/python/3.9/LINUX/X64/azure_functions_worker/dispatcher.py", line 407, in _handle__invocation_request call_result = await self._loop.run_in_executor( File "/usr/local/lib/python3.9/concurrent/futures/thread.py", line 58, in run result = self.fn(*self.args, **self.kwargs) File "/azure-functions-host/workers/python/3.9/LINUX/X64/azure_functions_worker/dispatcher.py", line 649, in _run_sync_func return ExtensionManager.get_sync_invocation_wrapper(context, File "/azure-functions-host/workers/python/3.9/LINUX/X64/azure_functions_worker/extension.py", line 215, in _raw_invocation_wrapper result = function(**args) File "/home/site/wwwroot/azure-function-timer/__init__.py", line 134, in main PATH_TO_FILE = wget.download("https://www.nasa.gov/sites/default/files/atoms/files/nasa_graphics_manual_nhb_1430-2_jan_1976.pdf", out=os.getcwd()) # wget to get the filename and path File "/home/site/wwwroot/.python_packages/lib/site-packages/wget.py", line 506, in download (fd, tmpfile) = tempfile.mkstemp(".tmp", prefix=prefix, dir=".") File "/usr/local/lib/python3.9/tempfile.py", line 336, in mkstemp return _mkstemp_inner(dir, prefix, suffix, flags, output_type) File "/usr/local/lib/python3.9/tempfile.py", line 255, in _mkstemp_inner fd = _os.open(file, flags, 0o600)

Check Azure logs, and filter logs by name of your function. What are logs saying? — Rafael
– Rafael, Commented Jun 10, 2022 at 12:19
Hi @Rafael, just edited my initial post to include the error log. — Merrick
– Merrick, Commented Jun 13, 2022 at 2:05
You are getting current working directory (cwd), also error states, that filesystem is readonly. In other words, you are trying to work in an incorrect folder. It is write-protected. To store temporary files in azure use `d:\local` folder. More info: stackoverflow.com/questions/38870950/… — Rafael
– Rafael, Commented Jun 13, 2022 at 8:12

Mohit Ganorkar · Accepted Answer · 2022-06-10 12:17:37Z

0

What you can do is containerize the function using docker and inside the container the place the file so that you can read the file later.

Because if you don't containerize the function, only the function's code will be deployed and not the file.

Refer this documentation for Indepth explanation.

answered Jun 10, 2022 at 12:17

Mohit Ganorkar

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