CODEWITHSUNDEEP
pythonnginxflaskgunicorn
Connie
Connie

Reputation: 1653

Nginx, Flask, Gunicorn 502 Error

I'm still pretty new with Flask/Nginx/Gunicorn as this is only my second site using the combination. I created a website based off of Miguel Grinberg's tutorial so my file structure is exactly the same as in this tutorial.

In my previous Flask app, my app was in a single file called app.py so when I used Gunicorn I just called
gunicorn app:app

Now that my new application is split into multiple files I used a file run.py to start the app, but I'm not sure how I should call Gunicorn now. I've read other questions and tutorials but they haven't worked. When I run gunicorn run:app and I try to access the site I get a 502 Bad Gateway error.

I think my problem is more Gunicorn than Nginx or Flask, since the site works if I just type ./run.py. In any case, I've included my Nginx config and a few other files below. Thanks so much for your help!

File: run.py

#!flask/bin/python
from app import app
from werkzeug.contrib.fixers import ProxyFix

app.wsgi_app = ProxyFix(app.wsgi_app)
app.run(debug = True, port=8001)

File: app/views.py

from app import app

@app.route('/')
@app.route('/index')
def index():
    posts = Post.query.order_by(Post.id.desc()).all()
    return render_template('index.html', posts=posts)

File: nginx.conf

server {
    listen 80;
    server_name example.com;

    root /var/www/example.com/public_html/app;

    access_log /var/www/example.com/logs/access.log;
    error_log /var/www/example.com/logs/error.log;

    client_max_body_size 2M;

    location / {
        try_files $uri @gunicorn_proxy;
    }

    location @gunicorn_proxy {
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;
        proxy_pass http://127.0.0.1:8001;
    }
}

Upvotes: 3

Views: 3630

Answers (1)

dirn
dirn

Reputation: 20709

What is happening is the development server is running when gunicorn imports app.py. You only want that to happen when the file is executed directly (e.g., python app.py). 

#!flask/bin/python
from app import app
from werkzeug.contrib.fixers import ProxyFix

app.wsgi_app = ProxyFix(app.wsgi_app)

if __name__ == '__main__':
    # You don't need to set the port here unless you don't want to use 5000 for development.
    app.run(debug=True)

Once you've made this change, you should be able to run the application with gunicorn run:app. Note that gunicorn uses port 8000 by default. If you wish to run on an alternate port (e.g., 8001), you'll need to specify that with gunicorn -b :8001 run:app.

Upvotes: 2

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