How to get the real IP of a client in a pyramid server behind a nginx proxy

Question

I have a Pyramid application which uses request.environ['REMOTE_ADDR'] in some places.

The application is served by Python Paste on port 6543 and a nginx server listening on port 80 is forwarding requests to the Paste server.

The nginx configuration is inspired by the Pyramid cookbook:

server {

    listen   80; ## listen for ipv4
    listen   [::]:80 default ipv6only=on; ## listen for ipv6

    server_name  localhost;

    access_log  /var/log/nginx/localhost.access.log;

    location / {

        proxy_set_header        Host $host;
        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_pass http://127.0.0.1:6543;

    }

In the Pyramid application the variable request.environ['REMOTE_ADDR'] is now always equal to 127.0.0.1. I see a few strategies to solve this problem but I don't know if there is a recommended way to do that.

Here is what I'm considering:

• add a NewRequest subscriber which replaces request.environ['REMOTE_ADDR'] if necessary:

  if 'HTTP_X_REAL_IP' in event.request.environ: event.request.environ['REMOTE_ADDR'] = event.request.environ['HTTP_X_REAL_IP']

• use a wsgi middleware to modify request.environ before hitting the Pyramid layer.

• something else

Which strategy do you use for deploying Pyramid applications ? What will happen if I have two nginx proxies ? (the first serving the LAN and a second one one a machine directly connected to the internet).

Answer 1

If you use the paste.deploy.config.PrefixMiddleware in your WSGI pipeline via use = egg:PasteDeploy#prefix, it will automatically translate X-Forwarded-For into REMOTE_ADDR. It is also great for other properties of your reverse proxy, for example it will translate X-Forwarded-Proto into wsgi.url_scheme to ensure that if the user visits with https then generated URLs are also https.

http://pythonpaste.org/deploy/class-paste.deploy.config.PrefixMiddleware.html