nginx / uwsgi-flask is changing port after form submission - nginx

Question

I set up a flask/uwsgi and a nginx container.
First of all, I could not access the site having nginx listen on port 80 and defining the docker port 80:80. No idea why this would not work.
So I made nginx listen on port 8090 and opening port 80:8090 in docker:
nginx:
container_name: fa_nginx
build:
context: ./nginx
dockerfile: Dockerfile
restart: unless-stopped
ports:
- 80:8090
networks:
- fa_nginx_net
I am not exposing any ports in the dockerfile, there I copy just the conf file.
## nginx conf
server {
listen 8090;
location / {
include /etc/nginx/uwsgi_params;
uwsgi_pass web:8087;
}
Like that, I can access the site at http://localhost and browser around e.g. to http://localhost/faq.
However, when I submit a form (login), the nginx changes to another port and the redirected url looks like http://localhost:8090/auth/login.
the redirect in flask's login view after successful form validation is simply return redirect(url_for('main.profile')).
Here is the flask/uwsgi setup (shortened version without all then env etc):
web:
container_name: fa_web
build:
context: ./web
dockerfile: Dockerfile
expose:
- "8087"
networks:
- fa_nginx_net
[uwsgi]
plugin = python3
## python file where flask object app is defined.
wsgi-file = run.py
## The flask instance defined in run.py
callable = fapp
enable-threads = false
master = true
processes = 2
threads = 2
## socket on which uwsgi server should listen
protocol=http
socket = :8087
buffer-size=32768
## Gives permission to access the server.
chmod-socker = 660
vacuum = true
## various
die-on-term = true
## run.py
from app import create_app, db
import os
## init flask app
fapp = create_app()
if __name__ == "__main__":
if os.environ.get('FLASK_ENV') == 'development':
fapp.run(use_reloader=True, debug=True, host='0.0.0.0', port=8086)
else:
fapp.run(host='0.0.0.0', port=8087)
I have no idea why this is happening and how to solve this.

Answer 1

Ok, it is working now...
Basically I removed plugin=python3 and protocol=http from uwsgi.ini.
My setup looks now like this
## nginx default.conf
server {
listen 8090;
#server_name fa_web;
## To map the server block to an ip:
#server_name 1.2.3.4;
## To map the server block to a domain:
#server_name example.com www.example.com;
location / {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header Host $http_host;
proxy_set_header X-NginX-Proxy true;
include /etc/nginx/uwsgi_params;
uwsgi_pass web:8087;
}
}
## uwsgi.ini
[uwsgi]
## python file where flask object app is defined.
wsgi-file = run.py
## The flask instance defined in myapp.py
callable = fapp
enable-threads = false
master = true
processes = 2
threads = 2
## socket on which uwsgi server should listen
socket = :8087
buffer-size=32768
#post-buffering=8192 ## workaround for consuming POST requests
## Gives permission to access the server.
chmod-socker = 660
vacuum = true
## various
die-on-term = true
The added headers in nginx conf didn't make a difference, just added them going forward configuring everything correctly.