debugging a uwsgi python application using pycharm

Question

Is it possible to debug a uwsgi application using an ide like PyCharm? I can debug flask based apps fine by running them directly from pycharm but cannot even run a uwsgi app from within pycharm.

Do I have to use remote debugging? Is it possible to start a uwsgi app from within pycharm using run?

Answer 1

You can still run your WSGI app outside of uWSGI for development and debugging purposes.

However sometimes this is not possible, for example if your app relies on uWSGI API features.

As far as I know you can't use "Attach to Process" from PyCharm because your WSGI app is running embedded into uWSGI, and there are no visible Python processes. Remote debugging however works like a charm.

1. Locate pycharm-debug*.egg files in your PyCharm distribution. For example, on OSX both can be found in /Applications/PyCharm.app/Contents

2. Copy pycharm-debug-py3k.egg next to your Flask app, or copy pycharm-debug.egg instead if you are using Python 2.7

3. In PyCharm, create a "Python Remote Debug" configuration from "Run/Debug Configurations" dialog. In this example I use localhost and port 4444. This dialog will show you the corresponding pydevd.settrace(...) line.

4. Add the following code to your app :

   import sys sys.path.append('pycharm-debug-py3k.egg')  # replace by pycharm-debug.egg for Python 2.7 import pydevd # the following line can be copied from "Run/Debug Configurations" dialog pydevd.settrace('localhost', port=4444, stdoutToServer=True, stderrToServer=True) 

5. In PyCharm, start the remote debugging session. PyCharm's console should display the following line :

   Waiting for process connection... 

6. Run your app from uWSGI as usual. It should attach to the debugger, and PyCharm's console should display :

   Connected to pydev debugger (build 139.711) 

7. Your app should break on the pydevd.settrace(...) line. You can then continue and use PyCharm debugger as usual (breakpoints and so on)

Answer 2

Not sure how to interpret your question, as you are mixing apples and oranges. Flask is a framework, uWSGI is an application server. I'll try to answer, though.

As far as I know, uWSGI is not pure python, so debugging it in PyCharm will not be trivial, if even it is possible.

However, since you are using uWSGI to run your application, I'm assuming it complies with the WSGI protocol. In that case, for debugging purposes, you can alternatively run it from a simple pure-python application engine like wsgiref.simple_server.WSGIServer.