Using python 3.6 on azure app services - not working despite it is installed as extension

Question

I've got a challenge with deploying Django app (wagtail to be precise) to Azure Web Services using external Git repo (Bitbucket). I want to use Python 3.6.1, therefore I followed instructions at Managing Python on Azure App Service manual

I have python 3.6.1 extension installed and in place
I created web.config file in root directory of my app (I checked and it is uploaded to the server)

However, deploy fails with message

Detecting Python runtime from runtime.txt
Unsupported runtime: python-3.6.1

Supported runtime values are:
python-2.7
python-3.4
An error has occurred during web site deployment.
\r\nD:\Program Files (x86)\SiteExtensions\Kudu\66.61008.3066\bin\Scripts\starter.cmd "D:\home\site\deployments\tools\deploy.cmd"

My web.config file

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <appSettings>
    <add key="PYTHONPATH" value="D:\home\site\wwwroot"/>
    <!-- Django apps only -->
    <add key="WSGI_HANDLER" value="django.core.wsgi.get_wsgi_application()"/>
    <add key="WSGI_LOG" value="D:\home\LogFiles\wfastcgi.log"/>
  </appSettings>
  <system.webServer>
    <handlers>
      <add name="PythonHandler" path="*" verb="*" modules="FastCgiModule"
           scriptProcessor="D:\home\python361x64\python.exe|D:\home\python361x64\wfastcgi.py"
           resourceType="Unspecified" requireAccess="Script"/>
    </handlers>
  </system.webServer>
</configuration>

Paths are ok, below is ls from Kudu console

D:\home\python361x64>ls
DLLs
Lib
Scripts
__pycache__
python.exe
python3.dll
python36.dll
pythonw.exe
sitecustomize.py
vcruntime140.dll
wfastcgi.py

It looks like the deployment process is not taking into account the web.config file that I have, or the python version that I've installed via extensions is not visible.

Could you please tell me where the possible issue could be?

Best regards,
Konrad

Familiar with building Docker images? Build your own (import from `python:3.6.3-jessie`) and deploy to App Service on a Linux worker. You'll be done in 15 minutes - https://learn.microsoft.com/en-us/azure/app-service/containers/tutorial-custom-docker-image — evilSnobu, Oct 23 '17 at 07:00
Thanks for your remark. Unfortunately I am not really keen on Docker, so, for now, I decided to go without it (I actually solved my issues and deployed the app). However, in future for sure I had to get more familiar with Docker as it is a really cool tool (I only used the already provided containers ;) ) — Konrad, Oct 23 '17 at 22:09

score 10 · Accepted Answer · answered Oct 23 '17 at 22:06

After a couple of hours of fighting, I finally managed to run this bastard as expected ;)

Thanks, @Jay Gong for your input as going step by step with this tutorial showed me a couple of things.

runtime.txt file, which I had in the root folder, was the first issue. As 3.6 version of python is installed via extensions, in fact, deployment process does not now that this v. exists (it "knows" only 2.7 and 3.4). So the first step was to get rid of this file.
When runtime.txt had been removed, deployment process has been using python 3.4 and was failing on installation one of the dependencies from requirements.txt file (probably because of the older version of python). So the next step was to add .skipPythonDeployment, to avoid automatic installation of requirements and install those manually by kudu console. In folder with our python env (in my case D:\home\python361x64) following command was launched
python.exe -m pip install --upgrade -r D:\home\site\wwwroot\requirements.txt
All dependencies were installed correctly.
After deploy, launching an app in a web browser showed message The page cannot be displayed because an internal server error has occurred.. Next step was to gather more info about the issue, so I have added a few new lines in web.config file:
```
....
<system.webServer>
....
    <httpErrors errorMode="Detailed"></httpErrors>
</system.webServer>
<system.web>
    ....
     <customErrors mode="Off" />
</system.web>
```
Thanks to that, I was able to check what is causing the issue. In my case, it was a WSGI_HANDLER value in web.config. I set it to a correct value (for wagtail it was <app_name>.wsgi.application and then it started working.

Thank you guys for all your support.

Thank you for your sharing. It's a good reference for me. Have a nice day! — Jay Gong, Oct 24 '17 at 01:22

score 3 · Answer 2 · answered Oct 23 '17 at 09:54

I tried to reproduce your issue but failed.I tried to deploy my own django web app to azure and it works.

You could refer to my steps and check if you you missed something.

Step 1: Follow the official tutorial to create your azure web app.

Step 2: Add Python extension.

Step 3: Add web.config file and deploy your web app.

<configuration>
  <appSettings>
    <add key="WSGI_HANDLER" value="<your project name>.wsgi.application"/>
    <add key="PYTHONPATH" value="D:\home\site\wwwroot"/>
    <add key="WSGI_LOG" value="D:\home\LogFiles\wfastcgi.log"/>
  </appSettings>
  <system.webServer>
    <handlers>
      <add name="PythonHandler" path="handler.fcgi" verb="*" modules="FastCgiModule" scriptProcessor="D:\home\python361x64\python.exe|D:\home\python361x64\wfastcgi.py" resourceType="Unspecified" requireAccess="Script"/>
    </handlers>
    <rewrite>
      <rules>
        <rule name="Static Files" stopProcessing="true">
          <conditions>
            <add input="true" pattern="false" />
          </conditions>
        </rule>
        <rule name="Configure Python" stopProcessing="true">
          <match url="(.*)" ignoreCase="false" />
          <conditions>
            <add input="{REQUEST_URI}" pattern="^/static/.*" ignoreCase="true" negate="true" />
          </conditions>
          <action type="Rewrite" url="handler.fcgi/{R:1}" appendQueryString="true" />
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

Step 4: Install pip plugin in your python extension environment.

Step 5: Install django module and other modules you want to use.

There are some similar SO threads you could refer to.

Hope it helps you.

Jay, I'm confused about the `pip plugin`. Where is the `python extension environment`? I can't find it in the Azure interface. — Chris May, Jun 01 '18 at 13:48
@ChrisMay You could find it on the kudu after you installed the python extension environment. — Jay Gong, Jun 11 '18 at 01:24

score 0 · Answer 3 · answered Jan 15 '18 at 22:06

I am posting the missing parts of Calfy answer.

<add key="WSGI_ALT_VIRTUALENV_HANDLER" value="app.wsgi_app" />
<add key="WSGI_ALT_VIRTUALENV_ACTIVATE_THIS" value="D:\home\python361x64\python.exe" />
<add key="WSGI_HANDLER" value="ptvs_virtualenv_proxy.get_venv_handler()"/>

app.wsgi_app is actually app.py in your folder and from what i understand it must be an wsgi app not regular python app.. (i also used cherrypy mod here) this sample app is copied somewhere from internet.

import sys
import cherrypy

class Hello(object):
    @cherrypy.expose
    @cherrypy.tools.response_headers(headers=[('Content-Type', 'text/plain')])
    def index(self):
        message = """\
Hello Azure!
Python: {python_version}
CherryPy: {cherrypy_version}

More info: http://blog.cincura.net/id/233498
"""
        return message.format(python_version=sys.version, cherrypy_version=cherrypy.__version__)


wsgi_app = cherrypy.Application(Hello(), '/')

if __name__ == '__main__':
    from wsgiref.simple_server import make_server

    httpd = make_server('', 6600, wsgi_app)
    httpd.serve_forever()

Using python 3.6 on azure app services - not working despite it is installed as extension

3 Answers3

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