Azure Functions: V2 Python Programming Model is Generally Available

The Azure Functions team is thrilled to share that the v2 programming model for Python is now Generally Available!

The v2 programming model enables customers to easily create Functions applications – leaning towards fewer Functions concepts and instead emphasizing Python principles. Key improvements include triggers and bindings declared as decorators, a simplified folder structure, and easy to reference documentation.

Note that leveraging the v2 model will alter how you create functions, but the underlying experience regarding monitoring, debugging, and deployment will remain the same.

We are so grateful for the community support of the new model and the feedback we have gotten since we brought the experience to Preview last fall. We've iterated on usability and increased out-of-the-box support for numerous triggers and bindings. Furthermore, running existing Flask and Fast API apps on Azure Functions, and leveraging generic triggers and bindings are now easier than ever, enabling customers to integrate with first and third-party extensions seamlessly.

Comparing v1 & v2

Following is an example of a Function Application with an HTTP trigger using both the v1 and the v2 programming models:

import azure.functions

def main(req: azure.functions.HttpRequest) -> str:
    user = req.params.get('user')
    return f'Hello, {user}!'

{
    "scriptFile": "__init__.py",
    "bindings": [
        {
            "authLevel": "function",
            "type": "httpTrigger",
            "direction": "in",
            "name": "req",
            "methods": [
                "get",
                "post"
            ]
        },
        {
            "type": "http",
            "direction": "out",
            "name": "$return"
        }
    ]
}

import azure.functions

app = func.FunctionApp()

@app.function_name(name="HttpTrigger1")
@app.route(route="req")
def main(req: azure.functions.HttpRequest) -> str:
    user = req.params.get('user')
    return f'Hello, {user}!'

Note that using the v1 programming model, there would be an 'init.py' and 'function.json' file for each function within the function application. When using the v2 programming model, all functions can be defined within the 'function_app.py' file. This significantly decreases the number of files and simplifies the folder structure, making it easier to manage applications. Additionally, the v2 programming model includes support for blueprints, such that multiple Python files can contain functions.

Supported Triggers and Bindings

Following are the triggers and bindings supported with decorators today:

If you want to use an extension for which there isn't a decorator available, you can use the generic triggers and bindings. For example, you can use generic decorators for the new Azure Data Explorer extension!

Integrating Web Applications that use ASGI & WSGI Frameworks

Have an existing web application using Flask or Fast API? Running it on Functions is easier than ever - check out the following examples!

ASGI

# function_app.py

import azure.functions as func 
from fastapi import FastAPI, Request, Response 

fast_app = FastAPI() 

@fast_app.get("/return_http_no_body") 
async def return_http_no_body(): 
    return Response(content='', media_type="text/plain") 

app = func.AsgiFunctionApp(app=fast_app, 
                           http_auth_level=func.AuthLevel.ANONYMOUS)

WSGI

# function_app.py

import azure.functions as func 
from flask import Flask, request, Response, redirect, url_for 

flask_app = Flask(__name__) 
logger = logging.getLogger("my-function") 

@flask_app.get("/return_http") 
def return_http(): 
    return Response('<h1>Hello World™</h1>', mimetype='text/html') 

app = func.WsgiFunctionApp(app=flask_app.wsgi_app, 
                           http_auth_level=func.AuthLevel.ANONYMOUS)

Finally, modify the host.json file to include the code:

"extensions": 
  {
    "http": 
    {
        "routePrefix": ""
    }
  }

As you can see, just by adding a few lines of code, you can get your existing web applications running on Functions. Learn more here and try it out today!

Troubleshooting & What's Next

We are continuing to iterate and improve the v2 programming model experience for our customers. At the time of release, there are still deployments in progress until all features are available. Learn about current caveats and upcoming features here.

Thank you to our community for the support and feedback on this programming model. Please continue to let us know what you think, and report any issues you face. Happy coding!