#AzureIoT – How to create an Azure IoT module from an Azure #CustomVision project 👀 3/N

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Hi !

In my previous post I wrote about how to create an Azure Custom Vision project. And, once created how to export the project as a Docker image to be used in different platforms. I also analyzed the content of the exported Linux image.

Today I´ll perform a similar analysis with an empty Azure IoT module. I created an Azure IoT Solution named [AzureIoTSolution], and I added a Python module named [ImageDrawingRecognitionModule]. The main solution content is described in the image below. We can find

  • Folder modules app. This folder contains the Azure Iot modules for the solution.
  • Folder ImageDrawingRecognitionModule. Main IoT module, includes several docker platform configuration files, python files for app [main.py] and requirements [requirements.txt]; and the module configuration [module.json].
  • Root files. Deploy template files for release and debug modules.
azure iot solution contents

As I mentioned, there are several platforms. For this post I’ll focus on the Raspberry Pi world, so let’s take a look at the content of the [Dockerfile.arm32v7].

  • It’s based on a Python 3.7 slim image for arm32v7
  • Install the following prerequisites: azure-iot-device~=2.0.0
  • Run the python app in the file [main.py]
FROM arm32v7/python:3.7-slim-buster

WORKDIR /app

COPY requirements.txt ./
RUN pip install -r requirements.txt

COPY . .

CMD [ "python3", "-u", "./main.py" ]

And finally, let’s take a look at the [main.py]. I cropped some of the code for a better readability.

  • Run the main() function in an async loop
  • Connect the module to Azure IoT based on the environment context information
  • Start a listener for input messages
  • Stop the module in local mode, when the letter Q is pressed
# Copyright (c) Microsoft. All rights reserved.
# Licensed under the MIT license. See LICENSE file in the project root for
# full license information.

import time
import os
import sys
import asyncio
from six.moves import input
import threading
from azure.iot.device.aio import IoTHubModuleClient

async def main():
    try:
        if not sys.version >= "3.5.3":
            raise Exception( "The sample requires python 3.5.3+. Current version of Python: %s" % sys.version )
        print ( "IoT Hub Client for Python" )

        # The client object is used to interact with your Azure IoT hub.
        module_client = IoTHubModuleClient.create_from_edge_environment()

        # connect the client.
        await module_client.connect()

        # define behavior for receiving an input message on input1
        async def input1_listener(module_client):

        # define behavior for halting the application
        def stdin_listener():

        # Schedule task for C2D Listener
        listeners = asyncio.gather(input1_listener(module_client))

        print ( "The sample is now waiting for messages. ")

        # Run the stdin listener in the event loop
        loop = asyncio.get_event_loop()
        user_finished = loop.run_in_executor(None, stdin_listener)

        # Wait for user to indicate they are done listening for messages
        await user_finished

        # Cancel listening
        listeners.cancel()

        # Finally, disconnect
        await module_client.disconnect()

    except Exception as e:
        print ( "Unexpected error %s " % e )
        raise

if __name__ == "__main__":
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())
    loop.close()

    # If using Python 3.7 or above, you can use following code instead:
    # asyncio.run(main())

This is a good start to merge the docker custom drawing files with the zure IoT project. I’ll start this on the next post.

Resources

Happy coding!

Greetings

El Bruno



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