Add ability to change Python version

[davidebbo]

If you go to the App Settings, you can change the Python version of the Web App, but that doesn't work at all and instead completely breaks the function app. That's because this setting is not designed for Functions at all.

Instead, with Functions, it uses whatever Python.exe is on the path (see code), which happens to be D:\Python27\python.exe.

We should provide a proper way of changing this.

[epaprat]

Actulaly we solved this issue with siteextensions.

Added to our template.json:

"resources": [
{
    "apiVersion": "2016-03-01",
    "name": "python2712x64",
    "type": "siteextensions",
    "properties": { },
    "dependsOn": [
        "[resourceId('Microsoft.Web/sites', parameters('siteName'))]"
     ]
 }

"HandlerMappings":[{
    "Arguments":"D:\\home\\Python27\\wfastcgi.py",
    "Extension":"fastCgi",
    "ScriptProcessor":"D:\\home\\Python27\\python.exe"
 }]

This way is pretty hacky but it works until this issue is solved.

[davidebbo]

@epaprat Nice! Thanks for sharing.

[christopheranderson]

won't be fixed in v1, will be addressed in 2.0

[asavaritayal]

We will no longer be adding new features to Functions 1.0.

Python support has been reintroduced on Functions 2.0 and python 3.6 is supported. You can follow the discussion here - https://aka.ms/functions-python-preview