Using supervisor as CRON

Problem

As you are seeing in the memmon example, supervisord is not executing memmon -a 200MB -m [email protected] at each event. Rather, it is starting this event listener once (or potentially a few times if you configure a pool) and then sends each new event over standard input of an existing process.

Solution

Consequently, you really need to find or write a supervisor compatible event listener for each additional type of capability you want to trigger on events.

Example Method of Implementation

Setup the configuration and write a listener

write a supervisord.cfg event section

[eventlistener:passthru]
command=/tmp/simple.py /bin/date -u +"%%s %%S:%%H:%%d:%%m"
events=TICK_60

(note- the escaping of % for configParser )

write a simple.py Event Listener

Create this simple.py listener by making changes to the example listener from the docs so it executes its first argument with any remaining arguments:

#! /usr/bin/python
import sys
import subprocess

def write_stdout(s):
    sys.stdout.write(s)
    sys.stdout.flush()

def write_stderr(s):
    sys.stderr.write(s)
    sys.stderr.flush()

def main(args):
    while 1:
        write_stdout('READY\n') # transition from ACKNOWLEDGED to READY
        line = sys.stdin.readline()  # read header line from stdin
        write_stderr(line) # print it out to stderr
        headers = dict([ x.split(':') for x in line.split() ])
        data = sys.stdin.read(int(headers['len'])) # read the event payload
        res = subprocess.call(args, stdout=sys.stderr); # don't mess with real stdout
        write_stderr(data)
        write_stdout('RESULT 2\nOK') # transition from READY to ACKNOWLEDGED

if __name__ == '__main__':
    main(sys.argv[1:])
    import sys

Make sure the supervisor configuration works

$ supervisorctl [-c cfg]
supervisor> status
passthru                         RUNNING   pid 4471, uptime 0:00:32
supervisor> tail passthru
  OKREADY
  RESULT 2
  OKREADY
  ...
supervisor> tail passthru stderr
supervisor> tail passthru stderr
  ver:3.0 server:supervisor serial:0 pool:passthru poolserial:0 eventname:TICK_60 len:15
  1451411161 01:17:29:12 <--- output
  when:1451411160ver:3.0 server:supervisor serial:1 pool:passthru poolserial:1 eventname:TICK_60 len:15
  1451411220 00:17:29:12 <--- output
  when:1451411220

Now date -u +"%s %S:%H:%d:%m" is running every 60 seconds.

Swapping in the desired command

create an executable script

/tmp/hiworld.php:

#! /usr/bin/php
<?= "hiya\n"; 

(chmod +x ...)

change the listener's arguments in supervisord.cfg

[eventlistener:passthru]
command=/tmp/simple.py /tmp/hiworld.php
;stdout_logfile=/tmp/passthru 
events=TICK_60
;autorestart=true
;startsecs=0

reload supervisord and test (reread seems not to detect this change)

supervisor> reload
   Really restart the remote supervisord process y/N? y
   Restarted supervisord
supervisor> status
   passthru                         RUNNING   pid 6017, uptime 0:00:10
supervisor> tail passthru stderr
supervisor> status
   passthru                         RUNNING   pid 6017, uptime 0:00:21
supervisor> status
   passthru                         RUNNING   pid 6017, uptime 0:01:01
supervisor> tail passthru stderr
   ver:3.0 server:supervisor serial:316 pool:passthru poolserial:0 eventname:TICK_60 len:15
    hiya
   when:1418926740
supervisor> 

End

Now the desired command is running every 60 seconds. You are now read to adjust particulars of permissions, locations, logs, etc.

Why invent the wheel? You can use cron and supervisord together.

In supervisord, create a task with autostart=false

In cron, use * * * * * supervisorctl start <taskname> to start the task every minute