Cron – Python script succeeds manually but fails on crontab

So I'm currently trying to get a script working but it's behaving differently when I run it manually than when I run it from crontab. Basically, I have a reverse ssh tunnel set up from one server to another, and in order to verify that my tunnel is up I:

• SSH from server A to server B
• Wget a test url from on server A from server B
• if Wget succeeds, I disconnect and do nothing
• if Wget fails, I disconnect and restart the tunnel

I know there are more elegant ways to verify ssh tunnels (like autossh and ServerKeepAlive), but for both policy and redundancy issues, I have to do things this way. Anyways, here's the script:

from __future__ import print_function
from __future__ import absolute_import

import os, sys, subprocess, logging, pexpect

COMMAND_PROMPT = '[#$] '
TERMINAL_PROMPT = '(?1)terminal type\?'
TERMINAL_TYPE = 'vt100'
SSH_NEWKEY = '(?i)are you sure you want to continue connecting'
SERVERS = [{address':'192.168.100.10', 'connString':'ssh user@192.168.100.10', 'testGet':'wget http://192.168.100.11/test.html -t 1 -T 10', 'tunnel':'start_tunnel'}, {address':'192.168.100.12', 'connString':'ssh user@192.168.100.12', 'testGet':'wget http://192.168.100.13/test.html -t 1 -T 10', 'tunnel':'start_tunnel2'}]

def main():

    global COMMAND_PROMPT, TERMINAL_PROMPT, TERMINAL_TYPE, SSH_NEWKEY, SERVERS

    #set up logging
    log = logging.getLogger(__name__)
    log.setLevel(logging.DEBUG)
    handler = logging.FileHandler('/home/user/tunnelTest.log')
    formatter = logging.Formatter('%(asctime)s - %(module)s.%(funcName)s: %(message)s')
    handler.setFormatter(formatter)
    log.addHandler(handler)


    for x in SERVERS:

        #connect to server
        child = pexpect.spawn(x['connString'])
        i = child.expect([pexpect.TIMEOUT, SSH_NEWKEY, COMMAND_PROMPT, '(?i)password'])
        if i == 0:   #Timeout
             log.debug('ERROR! Could not log in to ' + x['address'] + ' ...')
             sys.exit(1)
        if i = 1:    #No key cached
             child.sendline('yes')
             child.expect(COMMAND_PROMPT)
             log.debug('Connected to ' + x['address'] + '...')
        if i = 2:    #Good to go
             log.debug('Connected to ' + x['address'] + '...')
             pass

        #Housecleaning
        child.sendline('cd /tmp')
        child.expect(COMMAND_LINE)
        child.sendline('rm -r test.html')
        child.expect(COMMAND_LINE)

        log.debug('Testing service using ' + x['testGet'] + ' ...')
        child.sendline(x['testGet'])
        child.expect(COMMAND_PROMPT)
        if 'saved' in child.before.lower():
            log.debug('Tunnel working, nothing to do here!')
            log.debug('Disconnecting from remote host ' + x['address'] + '...')
            child.sendline('exit')
        else:
            log.error('Tunnel down!')
            log.debug('Disconnecting from remote host ' + x['address'] + ' and restarting tunnel')
            child.sendline('exit')
            subprocess.call(['start',x['tunnel']])
            log.debug('Autossh tunnel restarted')

if __name__ == "__main__":
    main()

My crontab entry is as follows:

0,30 * * * * python /home/user/tunnelTest.py

So yeah — this script runs fine when I do it manually (sudo python tunnelTest.py) and also runs fine on crontab unless a tunnel is down. When a tunnel is down, I get the "Tunnel down!" and "Disconnecting from remote host 192.168.100.10 and restarting tunnel" messages in my log, but the script seems to die there. The tunnel doesn't restart, and I get no messages in my log until the start of the next scheduled run.

The start_tunnel script is in /etc/init, the testTunnel.py script is in /home/user, the testTunnel.log file is in /home/user/logs, and I ran crontab -e as root.

Any insight into this matter would be greatly appreciated.

Thanks!