sysadmin

A simple way for Python cron tasks to exit if another process is currently running. Does not use a pidfile.

import os
import subprocess
import shlex


def bail_if_another_is_running():
    cmd = shlex.split("pgrep -u {} -f {}".format(os.getuid(), __file__))
    pids = subprocess.check_output(cmd).strip().split('\n')
    if len(pids) > 1:
        pids.remove("{}".format(os.getpid()))
        print "Exiting! Found {} is already running (pids): {}".format(
            __file__, " ".join(pids))
        raise SystemExit(1)

Although it’s been a few years since I switched from full-time Sysadmin to full-time Coder, being in a startup means getting saddled with an opsy task now and again regardless of your “title”.

The problem: We bought a bunch of servers which need minimal OS, IP and a hostname before they’re racked. In otherwords, we want to drop them in a datacenter, turn them on, and leave knowing there’s remote SSH access. Data centers are environmentally hostile (hot rows, cold rows, too loud). It’s ideal to get in and out as quickly as possible and do any remaining config while listening to music and having a cup of tea.