How to host a Flask app on a subfolder / URL prefix with Nginx?

Question

I have a flask app which I want to host it on a subfolder of a website, like example.com/cn.

I configured my nginx like

location /cn {
    proxy_pass http://localhost:8000/;
}

So if I access example.com/cn, It will redirect to the index page of flask.

However, I have wrote the routes of other pages on flask like app.route('/a'). So if I click the link of page a, the URI is example.com/a, then nginx cannot redirect it to the right page.

I think I can rewrite all the routes on flask like app.route('/cn/a'), but it's complex. And if someday I want to deploy it on example.com/en, I think I need to rewrite all the routes again.

Does anyone have other methods?

Matteo Pasini · Accepted Answer · 2021-05-28T13:59:57.547

You need to add APPLICATION_ROOT params to your flask app:

from flask import Flask, url_for
from werkzeug.serving import run_simple
from werkzeug.wsgi import DispatcherMiddleware

app = Flask(__name__)
app.config['APPLICATION_ROOT'] = '/cn'

if you need to host more than one application on your server, you can configure nginx to redirect all request to your specific flask app served by gunicorn like this. (it is not necessary if your server hosts only one application) Find out more about gunicorn and nginx here: https://docs.gunicorn.org/en/stable/deploy.html

server {
    listen 8000;
    server_name example.com;

    proxy_intercept_errors on;
    fastcgi_intercept_errors on;

    location / {
        include proxy_params;
        proxy_pass http://unix:/path_to_example_flask_app_1/app.sock;
    }

    location /cn/{
        include proxy_params;
        proxy_pass http://unix:/path_to_example_flask_app_cn/app.sock;
    }
}

serve flask app with gunicorn: A complete exmaple here: https://www.digitalocean.com/community/tutorials/how-to-serve-flask-applications-with-gunicorn-and-nginx-on-ubuntu-18-04

#move into project directory
/path_to_gunicorn/gunicorn --workers 3 --bind unix:app.sock -m 007 run:app

If you are using flask_restful instead, you can specify the root path also in the following way:

from flask import Flask
from flask_restful import Api

app = Flask(__name__)
app.debug = False
api = Api(app, prefix='/cn')

api.add_resource(ResourceClass, '/example_path') #will be served when the resource is requested at path /cn/example_path

if __name__ == '__main__':
    app.run(host="0.0.0.0", port=8000)

It looks like it's a solution. But when I try to set `app.config['APPLICATION_ROOT'] = '/cn'`, it has no use. I think the problem is from flask itself. — Hu Zhang, May 28 '21 at 14:49

score 1 · Answer 2 · answered May 28 '21 at 14:47

1

I have found a perfect solution here.

answered May 28 '21 at 14:47

Hu Zhang

95
1
7

Yep, this is the only one that worked for me. You do two things: add a session variable `SCRIPT_NAME=/cn` and use `url_for('my_function')` everywhere. He went through the same process we all went through. Really wish Flask would highlight this use case more in the docs. – Jonathan Mugan Sep 12 '22 at 04:07

score 0 · Answer 3 · answered May 28 '21 at 11:45

0

You can use url_prefix="/cn" option when defining blueprints:

https://flask.palletsprojects.com/en/2.0.x/blueprints/#nesting-blueprints

answered May 28 '21 at 11:45

JBLaf

776
5
10

score 0 · Answer 4 · answered Jan 15 '23 at 05:04

Suppose you want to host your application under /api with Nginx.

First, config your URL prefix to location and X-Forwarded-Prefix header:

server {
    listen 80;
    server_name _;

    location /api {
        proxy_pass http://127.0.0.1:5000/;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Forwarded-Host $host;
        proxy_set_header X-Forwarded-Prefix /api;
    }
}

Then use Werkzeug's ProxyFix middleware to tell Flask it's behind a proxy:

from werkzeug.middleware.proxy_fix import ProxyFix
from flask import Flask


app = Flask(__name__)
app.wsgi_app = ProxyFix(
    app.wsgi_app, x_for=1, x_proto=1, x_host=1, x_prefix=1
)

How to host a Flask app on a subfolder / URL prefix with Nginx?

4 Answers4

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