Add following lines in your wsgi file.
import os
http_proxy  = "10.10.1.10:3128"
https_proxy = "10.10.1.11:1080"
ftp_proxy   = "10.10.1.10:3128"
proxyDict = { 
              "http"  : http_proxy, 
              "https" : https_proxy, 
              "ftp"   : ftp_proxy
            }
os.environ["PROXIES"] = proxyDict
And Now you can use this environment variable anywhere you want,
r = requests.get(url, headers=headers, proxies=os.environ.get("PROXIES"))
P.S. - You should have a look at following links
- Official Python Documentation for Environment Variables
- Where and how do I set an environmental variable using mod-wsgi and django?
- Python ENVIRONMENT variables
UPDATE 1
You can do something like following so that proxy settings are only being used on localhost.
import socket
if socket.gethostname() == "localhost":
    # do something only on local server, e.g. setting os.environ["PROXIES"]
    os.environ["PROXIES"] = proxyDict
else:
    # Set os.environ["PROXIES"] to an empty dictionary on other hosts
    os.environ["PROXIES"] = {}