Use python to check if dev_appserver is running on localhost

Question

I have a script that I use to connect to localhost:8080 to run some commands on a dev_appserver instance. I use a combination of remote_api_stub and httplib.HTTPConnection. Before I make any calls to either api I want to ensure that the server is actually running.

What would be a "best practice" way in python to determine:

1. if any web server is running on localhost:8080
2. if dev_appserver is running on localhost:8080?

Answer 1

This should do it:

import httplib

NO_WEB_SERVER = 0
WEB_SERVER = 1
GAE_DEV_SERVER_1_0 = 2
def checkServer(host, port, try_only_ssl = False):
    hh = None
    connectionType = httplib.HTTPSConnection if try_only_ssl \
                                             else httplib.HTTPConnection
    try:
        hh = connectionType(host, port)
        hh.request('GET', '/_ah/admin')
        resp = hh.getresponse()
        headers = resp.getheaders()
        if headers:
            if (('server', 'Development/1.0') in headers):
                return GAE_DEV_SERVER_1_0|WEB_SERVER
            return WEB_SERVER
    except httplib.socket.error:
        return NO_WEB_SERVER
    except httplib.BadStatusLine:
        if not try_only_ssl:
            # retry with SSL
            return checkServer(host, port, True)
    finally:
        if hh:
            hh.close()
    return NO_WEB_SERVER

print checkServer('scorpio', 22)   # will print 0 an  ssh server
print checkServer('skiathos', 80)  # will print 1 for an apache web server
print checkServer('skiathos', 8080) # will print 3, a GAE Dev Web server
print checkServer('no-server', 80) # will print 0, no server
print checkServer('www.google.com', 80) # will print 1
print checkServer('www.google.com', 443) # will print 1