[转]Django app with HttpPlatformHandler in Azure App Services (Windows)

wfastcgi.py provides a bridge between IIS and Python using WSGI and FastCGI, similar to what mod_python provides for Apache HTTP Server.

Even though using wfastcgi was preferred way to run Python apps in IIS. I would like to provide an alternate solution using HTTP Platform Handler in this blog.

Below are list of steps we would follow

Create Sample Project
Create Azure WebApp and Use Site Extension to Upgrade Python
Create and Change Deployment script
Adding web.config (for production app use second option with waitress)
Publish App

You can find a Sample Python Django project with above operations @ GitHub Link

Create Sample Project

Follow https://www.djangoproject.com/start/ to get started with Django

Install Django and
Write your first Django app

(or)

If you have PyCharm, Follow details at below link to create a sample app
https://www.jetbrains.com/help/pycharm/2016.1/creating-django-project.html

Create Azure WebApp and Use Site Extension to Upgrade Python

Navigate to Azure portal

Create a new web app
Setup Continuous Deployment
Navigate to your App Service blade, select Extensions and then Add.
From the list of extensions, scroll down until you spot the Python logos, then choose the version you need

For this blog I’m choosing Python 2.7.12 x64, It would install new version of python @ D:\home\Python27

Create and Change Deployment script

I have explained more on how to utilize deployment script and what it does @ link. you can use this script to run commands on Azure App after moving code to it.

Install Azure Cli using below command

npm install azure-cli -g

Use Below command to create deployment script.

azure site deploymentscript --python

Above step would create below two files

.deployment
deploy.cmd

Note: If you haven’t used nodejs/npm earlier, Create above files manually and copy content for these files from https://github.com/prashanthmadi/azure-django-httphandler

Replace content of deploy.cmd file with content at Link

We are changing default deployment script(removing virtual environment creation and others) and adding below content to install packages listed in requirements.txt

python.exe -m pip install --upgrade -r requirements.txt

Adding web.config(Development Mode)

Note: Ignore this section for production app

Azure web apps would use IIS which can be configured using web.config file. In our web.config file we would ask the requests to use httpplatformhandler and forward them to python.exe

Create below file at root folder and copy content from link

web.config

<?xml version="1.0" encoding="UTF-8"?>  
<configuration>  
 <system.webServer>

  <handlers>
    <add name="httpPlatformHandler" path="*" verb="*"
               modules="httpPlatformHandler" resourceType="Unspecified"/>
  </handlers>

  <httpPlatform processPath="D:\home\Python27\python.exe" arguments="manage.py runserver %HTTP_PLATFORM_PORT%" requestTimeout="00:04:00" startupTimeLimit="120" startupRetryCount="3" stdoutLogEnabled="true">
    <environmentVariables>
     <environmentVariable name="PYTHONPATH" value="D:\home\site\wwwroot"/>
    </environmentVariables>
  </httpPlatform>

 </system.webServer>
</configuration>

Adding web.config(Production Mode - Using Waitress)

Waitress is meant to be a production-quality pure-Python WSGI server with very acceptable performance

Django app by default uses a development server which would be started when we execute manage.py file. I would provide steps to use Waitress instead below

Create web.config file with below content

<?xml version="1.0" encoding="UTF-8"?>  
<configuration>  
 <system.webServer>
  <handlers>
   <add name="httpPlatformHandler" path="*" verb="*" 
             modules="httpPlatformHandler" resourceType="Unspecified" />
  </handlers>

  <httpPlatform processPath="D:\home\Python27\python.exe"
 arguments="run_waitress_server.py" requestTimeout="00:04:00" startupTimeLimit="120" startupRetryCount="3" stdoutLogEnabled="true">
   <environmentVariables>
    <environmentVariable name="PYTHONPATH" value="D:\home\site\wwwroot" />
    <environmentVariable name="PORT" value="%HTTP_PLATFORM_PORT%" />
   </environmentVariables>
  </httpPlatform>
 </system.webServer>
</configuration>

If you observe carefully, we have changed

httpplatform arguments section to run_waitress_server.py instead of manage.py runserver %HTTP_PLATFORM_PORT%
Added new evnironmentVariable PORT to pass the internal port number we use in waitress

Add below line at the end in requirements.txt file. This would install waitress module during deployment

waitress==1.0.1

Create a new file run_waitress_server.py with below content

import os  
from waitress import serve  
from django.core.wsgi import get_wsgi_application  
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "djangosql.settings")  
application = get_wsgi_application()  
serve(application,host="0.0.0.0",port=os.environ["PORT"])

I have seen some Azure users facing issue with ssl. set url_scheme to resolve the issue as below

serve(application,host="0.0.0.0",port=os.environ["PORT"],url_scheme='https')

Publish App

Navigate to your root folder and commit your changes to WEB_APP_GIT_URL

git init  
git add .  
git commit -m "initial commit"  
git remote add sampledjangoapp WEB_APP_GIT_URL  
git push sampledjangoapp master

Serving Static Files

I have seen couple of users complaining about static files. Here is the fix for it

Use below line of code(at D:\home\site\wwwroot using kudu console) to generate static file folder in Django app, we can also stitch this inside deploy.cmd to automate it. Version number in url may change based on your python installation.

D:\home\python27\python.exe manage.py collectstatic --noinput

Once you have static folder in D:\home\site\wwwroot folder as above screenshot

Navigate to Azure Portal and add a new section in Virtual application and directories under Application Settings with below values

Navigate to D:\home\site\wwwroot\static folder and add web.config file with below content

D:\home\site\wwwroot\static\web.config content

<?xml version="1.0"?>  
<configuration>  
    <system.webServer>
        <handlers>
           <clear />
            <add 
                name="StaticFile"
                path="*" verb="*" modules="StaticFileModule,DefaultDocumentModule,DirectoryListingModule" 
                resourceType="Either" 
                requireAccess="Read" />
        </handlers>
    </system.webServer>
</configuration>