[USE_X_FORWARDED_HOST] drf application with proxy pass(nginx)

[Devansh3790]

Checklist

• I have verified that that issue exists against the master branch of Django REST framework.
• I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• This is not a usage question. (Those should be directed to the discussion group instead.)
• This cannot be dealt with as a third party library. (We prefer new functionality to be in the form of third party libraries where possible.)
• I have reduced the issue to the simplest possible case.
• I have included a failing test as a pull request. (If you are unable to do so we can still accept the issue.)

Steps to reproduce

1. Create a Django rest application following the given steps on the doc.

# app/urls.py

from django.urls import path, include
from django.contrib.auth.models import User
from rest_framework import routers, serializers, viewsets


# Serializers define the API representation.
class UserSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = User
        fields = ['url', 'username', 'email', 'is_staff']


# ViewSets define the view behavior.
class UserViewSet(viewsets.ModelViewSet):
    queryset = User.objects.all()
    serializer_class = UserSerializer


# Routers provide an easy way of automatically determining the URL conf.
router = routers.DefaultRouter()
router.register(r'users', UserViewSet)

# Wire up our API using automatic URL routing.
# Additionally, we include login URLs for the browsable API.
urlpatterns = [
    path('', include(router.urls)),
]

2. Dockerize application and run application localhost:8000 gives me following output.

{
    "users": "http://localhost:8000/users/"
}

3. Create an Nginx container and add a proxy for my application with 81 port

upstream app_server {
  server backend:8000; # backend is the docker-compose service name for my application
}
server {

  listen 81;
  server_name app_server;

  location / {
    # everything is passed to Gunicorn
    proxy_pass http://app_server;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $host;
    proxy_redirect off;
  }
}

4. opened localhost:81 application is working file but the problam with the response;

{
    "users": "http://localhost/users/"
}

Actual behavior

Here you can notice that the value for key users : "http://localhost/users/".

Expected behavior

It should be "http://localhost:81/users/".

I did a search on the problem and found the USE_X_FORWARDED_HOST from Django document. What explained there tried to search in DRF code but didn't find such kind of logic which will resolve this issue.

[Devansh3790]

Added a demo app.

[jules-ch]

The issue is a bit old but if you haven't found the solution, here it is.

Django is using by default the HOST Header to build the URL.
In your nginx config, you're using $host which is localhost.

First Solution
You can use this nginx config :

upstream app_server {
  server backend:8000; # backend is the docker-compose service name for my application
}
server {

  listen 81;
  server_name app_server;

  location / {
    # everything is passed to Gunicorn
    proxy_pass http://app_server;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $http_host;
    proxy_redirect off;
  }
}

http_host variable is the host with the port in nginx.

Second solution if you want to use USE_X_FORWARDED_HOST setting in Django.

In your settings file:

USE_X_FORWARDED_HOST=True

You need to set the X-Forwarded-Host header in your nginx config like so :

upstream app_server {
  server backend:8000; # backend is the docker-compose service name for my application
}
server {

  listen 81;
  server_name app_server;

  location / {
    # everything is passed to Gunicorn
    proxy_pass http://app_server;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-Host  $host:$server_port;
    proxy_redirect off;
  }
}