Tohuwabohu excorcism

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Azure function

Setting up IDE: Visual Studio Code

Use to reload the env variables after installing

$env:Path = `
[System.Environment]::GetEnvironmentVariable("Path","Machine") + ";" + `
[System.Environment]::GetEnvironmentVariable("Path","User")

Install packages locally, to make imports succeed

pip install -r .\requirements.txt

Make sure you select the right python version, for which you executed the “pip install”

Then even under windows one can run “func start” to test linux functions

func start

Debugging Azure functions

You can execute the Azure functions from the portal.

And you can validate the behavior via “Portal > Azure Function > Log Stream”

Azure functions in Azure Portal

The runtime

The trigger and code.

Only available after uploading the code into the function, via

az functionapp deployment source config-zip -g $resourceg -n $functionname –src app.zip

which uploads the app.zip into the associated blob-container, from where it automatically is executed by the azure_function.

Here the function http_trigger was recognized.

The Function URL

The URL response

Limitations of Azure functions

Azure functions - are NOT only serverless.
- You can choose a premium subscription and deploy your Azure function as an always running instance into your network
- You CAN'T use a serverless function - in a private network
You CAN'T have multiple triggers for a function. ONly one of
- http_trigger
- Blob trigger
- CosmosDB trigger
- EventHub trigger
- Queue trigger
- ServiceBus Queue trigger
- ServiceBus Topic trigger
- Timer Trigger

Serverless Azure functions

https://learn.microsoft.com/en-us/azure/azure-functions/functions-proxies

Python linux functions

https://learn.microsoft.com/en-us/azure/azure-functions/create-first-function-cli-python?tabs=linux%2Cbash%2Cazure-cli%2Cbrowser

Run like https://learn.microsoft.com/en-us/azure/azure-functions/create-first-function-cli-python?tabs=linux%2Cbash%2Cazure-cli%2Cbrowser#run-the-function-locally


func start

IN general read about developing locally: https://learn.microsoft.com/en-us/azure/azure-functions/functions-develop-local

Azure Service Bus Pub/Sub

Publishing function

import logging
import azure.functions as func

app = func.FunctionApp()

# vs output into queue for python
# https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-service-bus-output?tabs=python-v2%2Cisolated-process%2Cnodejs-v4%2Cextensionv5&pivots=programming-language-python

@app.route(route="http_trigger_queue", auth_level=func.AuthLevel.ANONYMOUS)
@app.service_bus_queue_output(arg_name="message",
                              connection="ServiceBusConnection",
                              queue_name="alfdevapi5servicebusqueue")
def http_trigger_queue(req: func.HttpRequest, message: func.Out[str]) -> func.HttpResponse:
    logging.info('Python HTTP trigger function processed a request.')

    logging.info('Python HTTP trigger function processed a request.')
    myMessage = "Hi alf this is my message via the queue to you."
    logging.info(myMessage)
    
    input_msg = req.params.get('message')
    message.set(f"{myMessage} {input_msg}")

    return func.HttpResponse(
        "This function should process queue messages.",
        status_code=200
    )

Subscribing function

import logging
import azure.functions as func

app = func.FunctionApp()


@app.service_bus_queue_trigger(arg_name="azservicebus", queue_name="alfdevapi5servicebusqueue",
                               connection="ServiceBusConnection") 
def servicebus_trigger(azservicebus: func.ServiceBusMessage):
    logging.warn('Python ServiceBus Queue trigger processed a message: %s',
                azservicebus.get_body().decode('utf-8'))

Here you can see, that when the publishing function is executed, via Test

Then the consuming function is receiving the message from the queue.

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