Overview
Universal callbacks are operations which are automatically attached to every job that is submitted. These are installed by a site administrator either on the Supervisor's local disk or on a file system which is accessible by the supervisor service.
Setting Up Universal Callbacks
To set up Universal Callbacks, the site administrator needs to make a directory (default $QBDIR/callback) and create a text-based configuration file, called "callbacks.conf" in that directory. Further, in the same directory, files containing the implementation (aka "code") of each Universal Callback must also be installed.
The callbacks.conf file serves as a map that tells the system which callback code should be triggered to run on what events.
The "callbacks.conf" file
The callbacks.conf file is a text file, much like qb.conf, containing one or more lines with a "key = value" pair, associating each implementation file to a trigger event. The syntax is:
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# lines starting with a hash mark are comments filename = trigger |
The filename points to a file in the same directory that implements the callback code. Note that Universal Callbacks support Python, Perl, and Qube callbacks, and the filename must have the extension .py, .pl, or .qcb, respectively.
The trigger specifies the triggering event that activates the callback, described in details at Triggers
Here's an example:
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# # callbacks.conf # # syntax of this file is : # filename = triggers # logFailuresToDB.py = failed-job-self mail-status.qcb = done-job-self checkWork.pl = done-work-self-* submitted.py = submit-job-self |
In this example, there are presumably 4 implementation files in the callback directory, logFailuresToDB.py, mail-status.qcb, submitted.py, and checkWork.pl, that have the implementation code in them.
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If you ever need to run an external script in a callback, we recommend the use of Do not use os.system() to run the external script, as this call will block until the external script exits. When a large number of callbacks tie up supervisor processes at the same time, your supervisor performance will suffer. |
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Do not call |
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#!/usr/bin/env python
import sys
import qb
import traceback
fh = open('/tmp/univeral_callback_test', 'a')
try:
# ==================================================
# === NOTE: ===
# the qb.jobinfo() in callbacks is not the
# same as the one in the external python API
# ==================================================
job = qb.jobinfo("-id", qb.jobid())[0]
fh.write('submitted %(id)s: %(name)s\n' % job)
except:
fh.write(traceback.format_exc())
fh.close()
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qb.conf Parameters
supervisor_universal_callback_path
- Path to the directory where Universal Callbacks (the callbacks.conf file and the implementation files) are found
- May be a comma-separated list to specify multiple locations
- default: $QBDIR/callback