Python script as systemd service not running

Question

I know there have been a lot of similar questions, but for the life of me I can't figure out what's wrong! I have a script that forwards a port via ssh tunnel, and it works pretty fine, and I want to run it as a service on startup using systemd. I already have other services running on my Pi as systemd services, and they work well, so I can't figure out why this one is not. I'm using Raspbian Jessie (server, no gui, headless Pi).

So, the unit file is as follows:

[Unit]
Description=SSH tunnel for DomoPro
After=multi-user.target sshd.service network.target

[Service]
Type=idle
ExecStart=/usr/bin/python /usr/bin/pyScripts/mkTunnel.py
ExecStop=/usr/bin/python /usr/bin/pyScripts/rmTunnel.py
StandardOutput=journal

[Install]
WantedBy=multi-user.target

and the python script, in case it's necessary, is as follows:

#!/usr/bin/python
import MySQLdb
from time import time,sleep
from subprocess import Popen,call,PIPE
import pycurl
from StringIO import StringIO
import json
from math import floor

print("DomoPro Tunnel Service")

def getSerial():
    cursor.execute("SELECT value FROM config WHERE var='serialKey'")
    cfg = cursor.fetchone()
    return cfg['value']

def setPort(port):
    sqlupdt = "UPDATE config SET value = '{0}' WHERE var='remotePort'".format(port)
    cursor.execute(sqlupdt)

def savePID(tunnelPID):
    sqlupdt = "UPDATE config SET value = '{0}' WHERE var='tunnelPID'".format(tunnelPID)
    cursor.execute(sqlupdt)

def clearPID():
    sqlupdt = "UPDATE config SET value = '' WHERE var='tunnelPID'"
    cursor.execute(sqlupdt)

def getTunnelData(serialKey):
    from urllib import urlencode
    ans = StringIO()
    serverURL = "server_address/phpfile.php"

    data_post = urlencode({"serialKey": serialKey})

    curl = pycurl.Curl()
    curl.setopt(curl.URL, serverURL)
    curl.setopt(curl.WRITEFUNCTION, ans.write)
    curl.setopt(curl.USERAGENT, "Some custom useragent")
    curl.setopt(curl.FAILONERROR, 1)
    curl.setopt(curl.CONNECTTIMEOUT, 10)
    curl.setopt(curl.HTTPHEADER,['Accept: application/json'])
    curl.setopt(curl.POST, 1)
    curl.setopt(curl.POSTFIELDS, data_post)
    try:
        curl.perform()
    except pycurl.error:
        return (False,False,False)

    curl.close()

    try:
        data = json.loads(ans.getvalue())
    except ValueError:
        return False
    else:
        (auth,port,isActive) = data['auth'], data['port'], data['isActive']

        if auth == "OK":
            return (auth,port,isActive)
        else:
            return (auth,False,False)

def openTunnel(port):
    if port:
        tunnel = call(['ssh','-fNq','-o','ConnectTimeout=5','-o','BatchMode=yes','-o','StrictHostKeyChecking=no','-o','ExitOnForwardFailure=yes','-R','{0}:localhost:443'.format(port),'user@server'])
        return tunnel
    else:
        return 1

def getpsPID():
    objPID = Popen('ps -C "ssh -fNq" -o pid=', shell=True, stdout=PIPE, stderr=PIPE)
    PID = objPID.communicate()[0].replace('\n','').replace(' ','')
    return PID

def getdbPID():
    cursor.execute("SELECT value FROM config WHERE var='tunnelPID'")
    cfg = cursor.fetchone()
    return cfg['value']

def makeTunnel():
    '''
    Return Codes:
        0: Ok
        1: Failed
        2: Not Active
        3: Auth Err
        4: Conn Err
    '''
    print("Opening tunnel...")
    serialKey = getSerial()
    (auth,port,isActive) = getTunnelData(serialKey)
    if auth == "OK":
        if isActive:
            setPort(port)
            tunnel = openTunnel(port)
            if not tunnel:
                tunnelPID = getpsPID()
                savePID(tunnelPID)
                print("Tunnel open")
                return 0
            else:
                clearPID()
                print("Tunnel failed")
                return 1
        else:
            setPort(0)
            clearPID()
            print("DomoPro Remote not active")
            return 2
    elif auth == "ERROR":
        setPort(0)
        clearPID()
        print("Auth error")
        return 3
    else:
        setPort(0)
        clearPID()
        print("Connection failed")
        return 4

def checkTunnel():
    print("Checking tunnel...")
    dbPID = getdbPID()
    psPID = getpsPID()
    if psPID:
        if dbPID != psPID:
            savePID(psPID)
        print("Tunnel open, PID:{}".format(psPID))
        return 0
    else:
        clearPID()
        print("Tunnel closed")
        return 1

db = MySQLdb.connect(   host="localhost",
                        user="user", 
                        passwd="pass", 
                        db="db")
db.autocommit(True)
cursor = db.cursor(MySQLdb.cursors.DictCursor)

tunnelState = checkTunnel()
if tunnelState:
    tunnelState = makeTunnel()
ts = time()
while True:
    currts = time()
    if (tunnelState == 0 or tunnelState == 1):
        timeoff = 120
        if (currts - ts) > timeoff:
            tunnelState = checkTunnel()
            if tunnelState:
                tunnelState = makeTunnel()
            ts = time()
        else:
            diff = timeoff - floor(currts - ts)
            print("Sleeping for {}s...".format(diff))
            sleep(diff)
    elif tunnelState == 2:
        timeoff = 3600
        if (currts - ts) > timeoff:
            tunnelState = makeTunnel()
            ts = time()
        else:
            diff = timeoff - floor(currts - ts)
            print("Sleeping for {}s...".format(diff))
            sleep(diff)
    elif tunnelState == 3:
        timeoff = 86400
        if (currts - ts) > timeoff:
            tunnelState = makeTunnel()
            ts = time()
        else:
            diff = timeoff - floor(currts - ts)
            print("Sleeping for {}s...".format(diff))
            sleep(diff)
    elif tunnelState == 4:
        timeoff = 300
        if (currts - ts) > timeoff:
            tunnelState = makeTunnel()
            ts = time()
        else:
            diff = timeoff - floor(currts - ts)
            print("Sleeping for {}s...".format(diff))
            sleep(diff)

cursor.close()

I also tried adding it to crontab using @reboot to no avail.

The script works flawlessly when run from command line.

You may notice there's another script running on service stop. It actually runs ok.

EDIT:

I followed Goldilocks' guide and wrapped the script like this:

#!/bin/bash
# Wrapper for mkTunnel.py

exec &>> /home/pi/log/tunnel.log
echo $(date)

# Fork/exec
(
        exec /usr/bin/python /usr/bin/pyScripts/mkTunnel.py
) &>> /home/pi/log/tunnel.log

exit 0

And it runs ok, but since my python script keeps running in background, and I guess that systemd is expecting an exit code, it shows an error message Job for tunnel.service failed. The journal shows the following:

Starting SSH tunnel for DomoPro...
tunnel.service start operation timed out. Terminating.
Failed to start SSH tunnel for DomoPro.
Unit tunnel.service entered failed state.

My current unit file is this:

[Unit]
Description=SSH tunnel for DomoPro
After=multi-user.target sshd.service network.target

[Service]
Type=forking
GuessMainPID=no
ExecStart=/usr/bin/pyScripts/tunnel.sh
ExecStop=/usr/bin/python /usr/bin/pyScripts/rmTunnel.py
StandardOutput=journal
StandardError=journal

[Install]
WantedBy=multi-user.target

How can I tell systemd not to timeout (or not to expect an exit code)?

EDIT 2:

It's working!! I forgot to remove verbosity from ssh and that was causing it to remain open, not returning an exit status for systemd. Thanks @goldilocks ;)