gevent simple dynamic reverse proxy

gsdproxy.py

#!/usr/bin/env python
from gevent import monkey 
monkey.patch_all()
import sys
import redis
import urllib2
import traceback
from cgi import escape

# -- gsdproxy 
# gevent simple dynamic reverse proxy
# ncode@karoly:~$ redis-cli 
# redis> set URL::MAP::<url>:<port> martinez.io
# OK
# based on: https://bitbucket.org/denis/gevent/src/14cdc044afd0/examples/webproxy.py
# -- ncode

PORT = 8000

def application(env, start_response):
    rds = redis.Redis()
    method = env['REQUEST_METHOD']
    http_host = env['HTTP_HOST']
    path = env['PATH_INFO']
    path = "http://%s/" % rds.get("URL::MAP::%s" % http_host)
    if env['PATH_INFO']: path += env['PATH_INFO']
    if env['QUERY_STRING']: path += '?' + env['QUERY_STRING']
    path = path.lstrip('/')
    if method == 'GET':
        return proxy(path, start_response)
    elif method == 'POST':
        start_response('404 Not Found', [])
    else:
        start_response('501 Not Implemented', [])

def proxy(path, start_response):
    try:
        try:
            response = urllib2.urlopen(path)
        except urllib2.HTTPError:
            response = sys.exc_info()[1]
        print ('%s: %s %s' % (path, response.code, response.msg))
        headers = [(k, v) for (k, v) in response.headers.items()]
    except Exception:
        ex = sys.exc_info()[1]
        sys.stderr.write('error while reading %s:\n' % path)
        traceback.print_exc()
        tb = traceback.format_exc()
        start_response('502 Bad Gateway', [('Content-Type', 'text/html')])
        error_str = escape(str(ex) or ex.__class__.__name__ or 'Error')
        return ['<h1>%s</h1><h2>%s</h2><pre>%s</pre>' % (error_str, escape(path), escape(tb))]
    else:
        start_response('%s %s' % (response.code, response.msg), headers)
        data = response.read()
        return [data]

if __name__ == '__main__':
    from gevent.pywsgi import WSGIServer
    print 'Serving on %s...' % PORT
    WSGIServer(('0.0.0.0', PORT), application).serve_forever()