I need to know if httplib library in Python will use the "http_proxy" variable set in my Linux OS environment variables.
As you can see in the source code of Lib/httplib.py, there is not call to os.environ which is the way to get/set environment variables, neither to any sort of environment reference. So the answer seems to be: no.
But you can call set_tunnel() using your env vars:
from os import environ
from urlparse import urlparse
url = urlparse(environ['http_proxy'])
conn.set_tunnel(url.hostname, url.port)
There are other attributes like url.username
and url.password
, see urlparse.