We Keep Coding

Deploying Python Falcon on Apache2 with mod_wsgi

Scenario: I'm using Python Falcon framework for my REST API service. The application is initially run by Gunicorn.
Right now when I call https://example.com:8000/, I get a proper response that the API logic dictates.
Goal: I want to deploy it on Apache2 along with mod_wsgi on my personal development server.
The API would still be running under Gunicorn, and Apache should interact with Gunicorn whenever a request is made on that end-point.
Directory structure:
| - abc_service
| - abc_service
| - __init__.py
| - app.py
| - wsgi.py
| - .abc_venv
The source code for app.py looks something like this:
import falcon
from .abc import ABC
api = application = falcon.API() # pylint: disable=invalid-name
# Creating a unique GET resource from the ABC class
test_handler_resource = ABC() # pylint: disable=invalid-name
# Mapping the HTTP GET endpoint with the unique resource
api.add_route('/abc', test_handler_resource)
# Mapping the HTTP POST endpoint with the unique resource
api.add_route('/abc/filters', test_handler_resource)
In my wsgi.py, I have the following contents:
from abc_service import application
The configuration for Apache in /etc/apache2/sites-available/000-default.conf is as follows:
# WSGI
WSGIDaemonProcess python-path=/home/uname/abc-service/src/abc_service/.abc_venv/lib/python3.5/site-packages
WSGIScriptAlias /abc /home/uname/abc-service/src/abc_service/wsgi.py
ProxyPass /abc http://localhost:8000/abc
ProxyPassReverse /abc http://localhost:8000/abc
<Location /abc>
AuthType None
Require all granted
# Always set these headers.
Header always set Access-Control-Allow-Origin "https://example.com"
Header always set Access-Control-Allow-Methods "POST, GET, OPTIONS, DELETE, PUT"
Header always set Access-Control-Max-Age "1000"
Header always set Access-Control-Allow-Headers "x-requested-with, Content-Type, origin, authorization, accept, client-security-token"
</Location>
I can't find any helpful resource on the web regarding the same on the web that uses this combination of Falcon, Gunicorn, mod_wsgi, and Apache. So, I can't figure out what I'm doing wrong.
I appreciate your time and help. Thanks!

So, a solution that worked for me was to add the WSGIPythonHome path to the Apache configuration.
WSGIPythonHome /var/local/abc-service/src/abc_service/.venv
The final Apache configuration looks like this:
# At the top of the Apache Config file
WSGIPythonHome /var/local/abc-service/src/abc_service/.venv
...
...
...
# WSGI
WSGIDaemonProcess python-path=/home/uname/abc-service/src/abc_service/.abc_venv/lib/python3.5/site-packages
WSGIScriptAlias /abc /home/uname/abc-service/src/abc_service/wsgi.py
ProxyPass /abc http://localhost:8000/abc
ProxyPassReverse /abc http://localhost:8000/abc
<Location /abc>
AuthType None
Require all granted
# Always set these headers.
Header always set Access-Control-Allow-Origin "https://example.com"
Header always set Access-Control-Allow-Methods "POST, GET, OPTIONS, DELETE, PUT"
Header always set Access-Control-Max-Age "1000"
Header always set Access-Control-Allow-Headers "x-requested-with, Content-Type, origin, authorization, accept, client-security-token"
</Location>

All logs being duplicated into apache error log

I have a flask project with logging set up by a config file.
This works as desired when running locally but when I run it under apache wsgi all of the log messages (not just errors) are written to the error.log file set up in the vhost as well.
After some googling I found this issue which I thought could be related and tried setting app.logger_name and calling app.logger but I'm still having the same issue.
config/logging.yaml: pastebin
Vhost:
<VirtualHost *:80>
ServerName myapp.com
WSGIDaemonProcess myapp home=/var/www/vhosts/myapp/httpdocs
WSGIScriptAlias / /var/www/vhosts/myapp/httpdocs/myapp.wsgi
<Directory /var/www/vhosts/myapp/httpdocs>
WSGIProcessGroup myapp
WSGIApplicationGroup %{GLOBAL}
Order deny,allow
Allow from all
</Directory>
ErrorLog /var/www/vhosts/myapp/logs/error.log
CustomLog /var/www/vhosts/myapp/logs/access.log combined
</VirtualHost>
myapp.wsgi:
activate_this = '/var/www/vhosts/myapp/httpdocs/env/bin/activate_this.py'
execfile(activate_this, dict(__file__=activate_this))
import sys
sys.path.insert(0, '/var/www/vhosts/myapp/httpdocs')
from run_web import app as application
run_web.py:
import init
import logging
from web import app, api
init.add_to_syspath()
init.logging_conf()
# Flask removes all log handlers so our logs are written to the error log as well.
app.logger_name = "nowhere"
app.logger
logger = logging.getLogger('run_web')
logger.info('Starting web')
api.init()
if __name__ == '__main__':
logger.info('Flask running in debug mode')
app.debug = True
app.run()
init.logging_conf():
def logging_conf():
with open('conf/logging.yaml', 'r') as yaml_file:
logging_config = yaml.load(yaml_file)
dictConfig(logging_config)

I have found that writing to stdout writes to the Apache error log. I have opened a more relevant question: How can I stop sys.stdout logging to apache error file?

How to get apache to serve static files on Flask webapp

I'm getting a 500 internal error while trying to get Apache to serve my static files.
The application will be locally hosted (not www facing). There will be no DNS to resolve a 'www.domain.com' name. I want to be able to access the application by entering the IP address of the server when I'm on that network.
This is my httpd.conf file (I'm on RHEL):
<Directory /var/www/testapp>
Order allow,deny
Allow from all
</Directory>
WSGIScriptAlias / /var/www/testapp/service.wsgi
If I change the WSGIScriptAlias to WGSIScriptAlias /test /var/www/testapp/service.wsgi then I can view my static files when I type in the IP, but I still can't access the service.py script from [IP]/test.
In any case, I want to be able to service all GET/POST requests with the service.py script so I want my alias to start at /, not some other place.
All my static files are in /var/www/html (Apache was automatically displaying these files before I messed with the httpd.conf, now I'm just getting a 500).
This is my service.wsgi:
import sys
sys.path.insert(0, '/var/www/testapp')
from service import app as application
This is my service.py:
from flask import Flask
app = Flask(__name__)
#app.route("/")
def hello(environ, start_response):
status = '200 OK'
output = "Hello"
response_headers = [('Content-type', 'text/plain'), ('Content-length', str(len(output)))]
start_response(status, response_headers)
return output
if __name__=='__main__'
app.run()
Do I need keep my .wsgi files in the /var/www/html directory as well? Or can they go in a different folder? I can see that there might be some conflict between the message I am sending to the server ('Hello') and the static files that are already in the /var/www/html/ directory. That's why I tried setting the alias to /test but that didn't work either.
I just want my Flask application to service GET/POST requests and want apache to serve all the static files.

Fixing the 500 errors
You are currently getting 500 errors because your handler is a basic WSGI handler, but Flask handlers are not WSGI handlers (Flask / Werkzeug abstracts all that for you). Change your handler to:
#app.route("/")
def hello():
return "Hello"
and the 500 errors should go away.
Serving static files with Apache
The following techniques can be used when your application is serving the root of the domain (/), depending on whether you are using WSGIScriptAlias or AddHandler.
When using WSGIScriptAlias
When using the WSGIScriptAlias to mount a WSGI application at / you can use an Apache Alias directive to ensure that certain sub-routes are not handled by WSGIScriptAlias (this is further documented in mod_wsgi's wiki as well):
Alias "/static/" "/path/to/app/static/"
<Directory "/path/to/app/static/">
Order allow,deny
Allow from all
</Directory>
If you also want to support blueprint static folders as well you'll also need to use the AliasMatch directive:
AliasMatch "(?i)^/([^/]+)/static/(.*)$" "/path/to/app/blueprints-root/$1/static/$2"
<Directory ~ "/path/to/app/blueprints-root/[^/]+/static/.*">
Order allow,deny
Allow from all
</Directory>
See also: The Directory directive.
When using AddHandler
As Graham Dumpleton has pointed out in the comments, you can use mod_rewrite to pass requests off to Python if and only if a file does not exist in DocumentRoot. Quoting from the linked docs:
When using the AddHandler directive, with WSGI applications identified by the extension of the script file, the only way to make the WSGI application appear as the root of the server is to perform on the fly rewriting of the URL internal to Apache using mod_rewrite. The required rules for mod_rewrite to ensure that a WSGI application, implemented by the script file 'site.wsgi' in the root directory of the virtual host, appears as being mounted on the root of the virtual host would be:
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)$ /site.wsgi/$1 [QSA,PT,L]
Do note however that when the WSGI application is executed for a request the 'SCRIPT_NAME' variable indicating what the mount point of the application was will be '/site.wsgi'. This will mean that when a WSGI application constructs an absolute URL based on 'SCRIPT_NAME', it will include 'site.wsgi' in the URL rather than it being hidden. As this would probably be undesirable, many web frameworks provide an option to override what the value for the mount point is. If such a configuration option isn't available, it is just as easy to adjust the value of 'SCRIPT_NAME' in the 'site.wsgi' script file itself.
from your.app import app # Your Flask app
import posixpath
def application(environ, start_response):
# Wrapper to set SCRIPT_NAME to actual mount point.
environ['SCRIPT_NAME'] = posixpath.dirname(environ['SCRIPT_NAME'])
if environ['SCRIPT_NAME'] == '/':
environ['SCRIPT_NAME'] = ''
return app(environ, start_response)
This wrapper will ensure that 'site.wsgi' never appears in the URL as long as it wasn't included in the first place and that access was always via the root of the web site instead.

Flask + apache Internal Server Error when making request or database

I'm using apache with flask and when opening /login (I use database here) i get Internal server Error
As database im using sqlite and python library sqlite3
DATABASE = '../../var/www/flask/database'
connecting database function :
def connect_db():
return sqlite3.connect(DATABASE)
login code
#app.route('/login', methods=['POST'])
def login():
if request.cookies.get("name"):
return render_template("home.html",name=request.cookies.get('name'))
g.db = connect_db()
cur = g.db.execute('SELECT email, password, name, confirmed FROM users')
for row in cur.fetchall():
if row[0] == request.form['email'] and row[1] == hashlib.sha224(request.form['password']).hexdigest() and row[3] == 1:
resp = make_response(redirect(host + "/home"))
resp.set_cookie("name",row[2])
resp.set_cookie("password",row[1])
return resp
return redirect(host)
here is my .wsgi code
import sys
sys.path.insert(0, '/var/www/flask/')
from routes import app as application
and here is my app tree
flask - static - (css js etc.)
- templates - (jinja2 template)
- database.db
- min.wsgi
- routes.py (app)
here is routes.com.conf
NameVirtualHost *:80
<VirtualHost *:80>
ServerName server.test
WSGIScriptAlias / /var/www/flask/min.wsgi
<Directory /var/www/flask/>
Order allow,deny
Allow from all
</Directory>
</VirtualHost>

You need to use an absolute path for your DATABASE value.
The mod_wsgi module will set a different current working directory for your app, one you most likely do not have access to. Even if you did give your Apache process write access to that directory, you don't want to end up changing a seemingly harmless setting elsewhere for it all to stop working again.

Maybe because of wrong indentation in login function? It would caused some very other error log probably, but it's my first guess when I'm looking at code formatted in wrong way (even if it's just wrong copy-paste).

Django: only blank page

I have a server with Apache and I would like to start website written in Django. I user mod_wsgi. Now I have it prepared. But the respond of a server is empty. And in error log, there is nothing. Do you know what is the reason why?
If some file could help (*.wsgi, settings.py) I will append it.
Prochazky.wsgi
import os
import sys
import site
os.environ['PYTHON_EGG_CACHE'] = '/home/prochazky/venv/.python-eggs'
site.addsitedir('/home/prochazky/venv/lib/python2.6/site-packages')
os.environ['DJANGO_SETTINGS_MODULE'] = 'Prochazky.settings'
sys.path.append('/home/prochazky/')
sys.path.append('/home/prochazky/Prochazky/')
import django.core.handlers.wsgi
application = django.core.handlers.wsgi.WSGIHandler()
Apache vhost:
<VirtualHost *:80>
WSGIScriptAlias / /home/prochazky/Prochazky/Prochazky.wsgi
ServerName testing.prochazky.net
DocumentRoot /home/prochazky
ErrorLog /home/prochazky/wsgi.log
</VirtualHost>

Trying getting a hello world program working first and not Django. Watch:
http://code.google.com/p/modwsgi/wiki/WhereToGetHelp?tm=6#Conference_Presentations
and read:
http://code.google.com/p/modwsgi/wiki/QuickConfigurationGuide
At a guess though, are you perhaps loading mod_python into the same Apache. An incompatible mod_python will cause exactly that symptom with merely a segmentation fault message in main Apache error log.
UPDATE 1
Are you loading mod_php into same Apache? It can sometimes have conflicting shared library requirements and will cause a crash. If you are also loading it, disable it from Apache configuration.
Also try setting:
WSGIApplicationGroup %{GLOBAL}
This will force use of main interpreter which will avoid problems with third party extensions that aren't written properly to work in sub interpreters.
You really though need to look more closely at the main Apache error log, not the virtual host one. Run a 'tail -f' on it when you make a request and check for sure you are seeing messages there, specifically a segmentation fault or similar message. Such a message about process crashing and causing empty page will not show in virtual host error log.

Is it possible the template file your root url/view is empty or evaluates to empty?
For instance, if you have a template like so:
{% extends "base.html" %}
{% block content %}blah blah{% endblock %}
and base.html doesn't use a block "content", then the content block from your template won't be used and your template will evaluate to empty despite having content.

This is from my setup (names altered to protect the innocent guilty).
<VirtualHost *:80>
ServerName site.domain.com
ServerAdmin webmaster#domain.com
WSGIScriptAlias / /home/user/site/django.wsgi
<Directory /home/user/site/>
Options FollowSymLinks
AllowOverride None
Order allow,deny
allow from all
</Directory>
... etc etc etc.
I think you need the <directory> to allow the server to access the .wsgi.
I'm really not an apache guru though so don't take this example as perfect. (I think all that is needed is the order Allow, deny and allow from all)
a good site to check out: http://code.google.com/p/modwsgi/wiki/IntegrationWithDjango