HttpTrigger Execute one after another using python

Question

I have created one HttpTrigger Azure functions using python. But I want to create another one HttpTrigger Azure Functions using python in the same project. In this application I want to execute first HttpTrigger Azure functions after that second HttpTrigger Azure functions execute. How can I implement that?

Because in Python Azure Functions there is no Durable Functions. That's why I am not able to understood how can I execute one after another azure function executes.

Just call the public URL (https://<functionapp>.azurewebsites.net/api/<function>) of the second function from your first function. You could convert the 2nd function to trigger on a queue and output a queue message from your first HttpTrigger function.. but that's just gratuitous complexity unless you absolutely need it. — evilSnobu
@evilSnobu Thanks for the reply. I will check and update you — Akshay Godase

Peter Pan Peter Pan · Accepted Answer · 2019-07-31T10:21:47

Assumed there are two HttpTrigger functions HttpTriggerA and HttpTriggerB, a direct solution in my mind is to request the public url of HttpTriggerA from HttpTriggerB function via a HTTP client request using requests, as the code below in my first version of HttpTriggerB code.

import logging

import azure.functions as func
import requests
from urllib.parse import urlparse

def main(req: func.HttpRequest) -> func.HttpResponse:
    logging.info('Python HTTP trigger function processed a request.')

    name = req.params.get('name') or 'Peter Pan'
    codeA = req.params.get('codeA') or ''
    o = urlparse(req.url)
    if not name:
        try:
            req_body = req.get_json()
        except ValueError:
            pass
        else:
            name = req_body.get('name')

    if name:
        print("B be invoked.")
        resp = requests.get(f"{o.scheme}://{o.netloc}/api/HttpTriggerA?name={name}&code={codeA}")
        return func.HttpResponse(f"Hello {name}! from B {resp.status_code == 200 and resp.text or ''}")
    else:
        return func.HttpResponse(
             "Please pass a name on the query string or in the request body",
             status_code=400
        )

However, it will not work after I test the code above on local or on Azure. It will hang at the code line resp = requests.get(f"{o.scheme}://{o.netloc}/api/HttpTriggerA?name={name}&code={codeA}"), when I access the url http(s)://<the host of local or Azure>:<7071 or 80>/api/HttpTriggerB?name=Peter%20Pan&code=<code for HttpTriggerB>&codeA=<code for HttpTriggerA>. The reason for the hang issue seems to be caused by functions running in singleton or in single thread.

So I switched to the other solution to use Ajax request from the html content of HttpTriggerB. It works as I wish as the figure below.

Here is my code for HttpTriggerB function, the HttpTriggerA function is simply generated by func new.

import logging

import azure.functions as func
#import requests
from urllib.parse import urlparse

def main(req: func.HttpRequest) -> func.HttpResponse:
    logging.info('Python HTTP trigger function processed a request.')

    name = req.params.get('name') or 'Peter Pan'
    codeA = req.params.get('codeA') or ''
    o = urlparse(req.url)
    if not name:
        try:
            req_body = req.get_json()
        except ValueError:
            pass
        else:
            name = req_body.get('name')

    if name:
        print("B be invoked.")
        #resp = requests.get(f"{o.scheme}://{o.netloc}/api/httptriggera?name={name}&code={req.params.get('codeA')}")
        html = """
<script src="https://code.jquery.com/jquery-3.4.1.min.js"></script>

Hello """+name+"""! from B<br/>
<span id="A"></span>

<script>
$.when( 
  $.get('"""+o.scheme+'://'+o.netloc+'/api/HttpTriggerA?name='+name+'&code='+codeA+"""'),
  $.ready
).done(function( data ) {
  $( "#A" ).html( data[0] );
});
</script>
"""
        return func.HttpResponse(html, mimetype="text/html")
    else:
        return func.HttpResponse(
             "Please pass a name on the query string or in the request body",
             status_code=400
        )

Hope it helps.

HttpTrigger Execute one after another using python

1 Answers