Flask in uWSGI causing 500 Internal Server Error just from importing SQLAlchemy

Question

TL;DR Edit: I didn't have the correct folder permissions set up.

---

Everything works fine when I run flask via source venv/bin/activate && python run.py.

from flask import Flask
from flask.ext.sqlalchemy import SQLAlchemy

app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello, world!"

if __name__ == "__main__":
    app.debug = True
    app.run(host='0.0.0.0', port=8080)

But when I run the same app with nginx/emperor.uwsgi then every hit to the server returns 500. If I comment out the SQLAlchemy import then the page loads, as expected.

---

Per this thread I've tried enabling lazy/lazy-app, but it has no effect. Flask is raising the exception, so nginx/uwsgi is not logging anything.

I've tried utilizing from werkzeug.debug import DebuggedApplication but still just getting absolute bare-bones "Internal Server Error" in my browser.

---

Config:

[uwsgi]
uid = http
gid = http

socket = /var/run/project.uwsgi.sock
chown-socket = http
chmod-socket = 664

pidfile = /var/run/project.master.pid

master = true
lazy = true
lazy-apps = true

chdir = /srv/http/project
python-path = /srv/http/project
virtualenv = /srv/http/project/venv
module = run
callable = app
plugin = python
home = venv

Nothing unusual.

---

source venv/bin/activate && pip list && deactivate output:

Flask (0.10.1)
Flask-SQLAlchemy (2.0)
itsdangerous (0.24)
Jinja2 (2.7.3)
MarkupSafe (0.23)
pip (6.0.8)
setuptools (12.0.5)
SQLAlchemy (0.9.9)
uWSGI (2.0.9)
Werkzeug (0.10.1)

All the usual suspects are present.

Completely in the dark on this one, anybody know how to debug/handle this?

Answer 1

Do you install uwsgi-emperor through the package manger as well?

Please make sure you are tracing with correct uwsgi.

Sometimes installing uwsgi from pip and apt make this problem. I myself replace the /usr/bin/uwsgi with /usr/local/bin/uwsgi in /etc/init.d/uwsgi.

Also you should check the path permissions and db access if any.