crontab python subprocess and service restart

Question

I have a small python code that restarts nginx on it's not existing. When I run sudo python monitor_server.py all is fine. When I tried to cron it with root cron (sudo crontab -e) with the line:
* * * * * python /root/monitor_server.py > /var/log/my_monitor/cron_log.log 2>&1 I get:

Traceback (most recent call last):
  File "/root/monitor_server.py", line 19, in <module>
    restart_service('mongod')
  File "/root/monitor_server.py", line 10, in restart_service
    subprocess.call(command, shell=False)
  File "/usr/lib64/python2.6/subprocess.py", line 478, in call
    p = Popen(*popenargs, **kwargs)
  File "/usr/lib64/python2.6/subprocess.py", line 642, in __init__
    errread, errwrite)
  File "/usr/lib64/python2.6/subprocess.py", line 1234, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory

The code:

def restart_service(name):
    command = ['service', name, 'restart'];
    #shell=FALSE for sudo to work.
    subprocess.call(command, shell=False)

if __name__ == '__main__':
    try:
        f = urllib2.urlopen("<healthcheck URL>")
    except (urllib2.HTTPError, urllib2.URLError) as e:
        logging.log(logging.ERROR, 'restarting server')
        restart_service('nginx')

try calling `service` with absolute path, like `usr/sbin/service`. — Jan Vlcinsky, Jun 11 '14 at 09:33
@ChristianBerendt - tried making moni work for hours. It didn't restart my nginx no matter what I tried — Boaz, Jun 11 '14 at 09:52
@Boaz Sorry for a typo, there should be leading slash, so you shall try `/usr/sbin/service` (or what ever you get returned by `which service`). Anyway, I do not guarantee, it would work, just an idea. — Jan Vlcinsky, Jun 11 '14 at 09:53
@JanVlcinsky - It worked thanks! It's funny how you neglect double checking when getting an answer on stackoverflow... Write it as an answer to get accetped — Boaz, Jun 11 '14 at 09:56

score 4 · Accepted Answer · answered Jun 11 '14 at 10:01

Try calling the command using absolute path, as you call it without shell and under another user account, some commands are not available without specifying absolute path.

First find, where is the command located:

$ which service
/usr/sbin/service

Then change your code to:

def restart_service(name):
    command = ['/usr/sbin/service', name, 'restart'];
    #shell=FALSE for sudo to work.
    subprocess.call(command, shell=False)

crontab python subprocess and service restart

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