gocept.runner 0.5

Create stand alone programs with full ZCA

Creating runners

The gocept.runner package allows it to easily create small, long running scripts which interact with the ZODB. The scripts have the full component architecture set up when they’re run.

Contents

• Creating runners

  • Signals

  • Setting the principal

  • Subsites

• Run once commands

• Runner details

  • Main loop

  • Controlling sleep time

• Changes

  • 0.5 (2009-09-21)

  • 0.4 (2009-09-03)

  • 0.3.2 (2009-05-21)

  • 0.3.1 (2009-05-21)

  • 0.3 (2009-04-15)

  • 0.2 (2009-04-09)

  • 0.1 (2009-04-07)

Runners are defined with the appmain decorator:

>>> import logging
>>> import gocept.runner
>>> work_count = 0
>>> @gocept.runner.appmain(ticks=0.1)
... def worker():
...     import zope.app.appsetup.product
...     log = logging.getLogger('test')
...     log.info("Working")
...     log.info(sorted(
...         zope.app.appsetup.product.getProductConfiguration('test').items()))
...     global work_count
...     work_count += 1
...     if work_count >= 3:
...         return gocept.runner.Exit

The decorated worker takes two arguments now:

1. The name of an object in the root which will be set as site or None for the root.

2. The path to a configuration file (zope.conf)

Create a simple zope.conf:

>>> import os.path
>>> import tempfile
>>> zodb_path = tempfile.mkdtemp()
>>> site_zcml = os.path.join(
...     os.path.dirname(__file__), 'ftesting.zcml')
>>> fd, zope_conf = tempfile.mkstemp()
>>> zope_conf_file = os.fdopen(fd, 'w')
>>> zope_conf_file.write('''\
... site-definition %s
... <zodb>
...   <filestorage>
...     path %s/Data.fs
...   </filestorage>
... </zodb>
... <product-config test>
...     foo bar
...     test-principal zope.mgr
... </product-config>
... <accesslog>
...   <logfile>
...     path STDOUT
...   </logfile>
... </accesslog>
... <eventlog>
...   <logfile>
...     formatter zope.exceptions.log.Formatter
...     path STDOUT
...   </logfile>
... </eventlog>
... ''' % (site_zcml, zodb_path))
>>> zope_conf_file.close()

So call the worker:

>>> worker(None, zope_conf)
------
... INFO test Working
------
... INFO test [('foo', 'bar'), ('test-principal', 'zope.mgr')]
------
... INFO test Working
------
... INFO test [('foo', 'bar'), ('test-principal', 'zope.mgr')]
------
... INFO test Working
------
... INFO test [('foo', 'bar'), ('test-principal', 'zope.mgr')]

Signals

The worker-procss can be terminated by SIGTERM and SIGHUP in a sane way. Write a script to a temporary file:

>>> import sys
>>> runner_path = os.path.abspath(
...     os.path.join(os.path.dirname(__file__), '..', '..'))
>>> fd, script_name = tempfile.mkstemp(suffix='.py')
>>> exchange_fd, exchange_file_name = tempfile.mkstemp()
>>> script = os.fdopen(fd, 'w')
>>> script.write("""\
... import sys
... sys.path[0:0] = %s
... sys.path.insert(0, '%s')
... import gocept.runner
...
... f = open('%s', 'w')
...
... @gocept.runner.appmain(ticks=0.1)
... def worker():
...     f.write("Working.\\n")
...     f.flush()
...
... worker(None, '%s')
... """ % (sys.path, runner_path, exchange_file_name, zope_conf))
>>> script.close()

Call the script and wait for it to produce some output:

>>> import signal
>>> import subprocess
>>> import time
>>> exchange = os.fdopen(exchange_fd, 'r+')
>>> proc = subprocess.Popen(
...     [sys.executable, script_name],
...     stdout=subprocess.PIPE)
>>> while not exchange.read():
...     time.sleep(0.1)
...     exchange.seek(0, 0)
>>> exchange.seek(0, 0)
>>> print exchange.read(),
Working.

Okay, now kill it:

>>> os.kill(proc.pid, signal.SIGTERM)

Wait for the process to really finish and get the output. The runner logs that it was terminated:

>>> stdout, stderr = proc.communicate()
>>> print stdout,
------
... INFO gocept.runner.runner Received signal 15, terminating.

This also works with SIGHUP:

>>> exchange.truncate(0)
>>> proc = subprocess.Popen(
...     [sys.executable, script_name],
...     stdout=subprocess.PIPE)
>>> while not exchange.read():
...     time.sleep(0.1)
...     exchange.seek(0, 0)
>>> exchange.seek(0, 0)
>>> print exchange.read(),
Working.

Okay, now kill it:

>>> os.kill(proc.pid, signal.SIGHUP)
>>> stdout, stderr = proc.communicate()
>>> print stdout,
------
... INFO gocept.runner.runner Received signal 1, terminating.

Clean up:

>>> os.remove(script_name)
>>> os.remove(exchange_file_name)

Setting the principal

It is also prossible to create a main loop which runs in an interaction:

>>> def get_principal():
...     return 'zope.mgr'

>>> import zope.security.management
>>> work_count = 0
>>> def interaction_worker():
...     global work_count
...     work_count += 1
...     if work_count >= 3:
...         raise SystemExit(1)
...     log = logging.getLogger('test')
...     interaction = zope.security.management.getInteraction()
...     principal = interaction.participations[0].principal
...     log.info("Working as %s" % principal.id)
>>> worker = gocept.runner.appmain(ticks=0.1, principal=get_principal)(
...     interaction_worker)

Call the worker now:

>>> worker(None, zope_conf)
------
... INFO test Working as zope.mgr
------
... INFO test Working as zope.mgr

After the worker is run there is no interaction:

>>> zope.security.management.queryInteraction() is None
True

It’s quite common to read the principal from zope.conf. Therefore there is a helper which makes this task easier:

>>> work_count = 0
>>> worker = gocept.runner.appmain(
...     ticks=0.1,
...     principal=gocept.runner.from_config('test', 'test-principal'))(
...     interaction_worker)
>>> worker(None, zope_conf)
------
... INFO test Working as zope.mgr
------
... INFO test Working as zope.mgr

[1]

The principal used to be set directly in the decorator. Since the principal is configuration this behaviour is deprecated.

>>> work_count = 0
>>> worker = gocept.runner.appmain(ticks=0.1, principal='zope.mgr')(
...     interaction_worker)

Subsites

It is possible to directly work on sites inside the root. The site must already exist of course, otherwise there will be an error:

>>> worker('a-site', zope_conf)
Traceback (most recent call last):
    ...
KeyError: 'a-site'

Clean up:

>>> import shutil
>>> shutil.rmtree(zodb_path)
>>> os.remove(zope_conf)

Run once commands

It is often needed to run a command once (or via cron) with the full component architecture. Usually zopectl run is used for this.

>>> import logging
>>> import gocept.runner
>>> import zope.app.component.hooks
>>> @gocept.runner.once()
... def worker():
...     log = logging.getLogger('test')
...     log.info("Working.")
...     site = zope.app.component.hooks.getSite()
...     if hasattr(site, 'store'):
...         log.info("Having attribute store.")
...     site.store = True

Define a Zope environment:

>>> import os.path
>>> import tempfile
>>> zodb_path = tempfile.mkdtemp()
>>> site_zcml = os.path.join(
...     os.path.dirname(__file__), 'ftesting.zcml')
>>> fd, zope_conf = tempfile.mkstemp()
>>> zope_conf_file = os.fdopen(fd, 'w')
>>> zope_conf_file.write('''\
... site-definition %s
... <zodb>
...   <filestorage>
...     path %s/Data.fs
...   </filestorage>
... </zodb>
... <product-config test>
...     foo bar
... </product-config>
... <accesslog>
...   <logfile>
...     path STDOUT
...   </logfile>
... </accesslog>
... <eventlog>
...   <logfile>
...     formatter zope.exceptions.log.Formatter
...     path STDOUT
...   </logfile>
... </eventlog>
... ''' % (site_zcml, zodb_path))
>>> zope_conf_file.close()

So call the worker for the first time. It will be terminated after one call:

>>> worker(None, zope_conf)
------
... INFO test Working.

Calling it a second time indicates that a property was changed in the first run:

>>> worker(None, zope_conf)
------
... INFO test Working.
------
... INFO test Having attribute store.
...

Runner details

Main loop

The main loop loops until it encounters a KeyboardInterrupt or a SystemExit exception and calls the worker once a second.

Define a worker function which exits when it is called the 3rd time:

>>> work_count = 0
>>> def worker():
...     print "Working"
...     global work_count
...     work_count += 1
...     if work_count >= 3:
...         raise SystemExit(1)

Call the main loop:

>>> import gocept.runner.runner
>>> gocept.runner.runner.MainLoop(getRootFolder(), 0.1, worker)()
Working
Working
Working
>>> work_count
3

During the loop the site is set:

>>> import zope.app.component.hooks
>>> zope.app.component.hooks.getSite() is None
True
>>> def worker():
...     print zope.app.component.hooks.getSite()
...     raise SystemExit(1)
>>> gocept.runner.runner.MainLoop(getRootFolder(), 0.1, worker)()
<zope.site.folder.Folder object at 0x...>

After the loop, no site is set again:

>>> zope.app.component.hooks.getSite() is None
True

When the worker passes without error a transaction is commited:

>>> work_count = 0
>>> def worker():
...     print "Working"
...     global work_count
...     work_count += 1
...     if work_count >= 2:
...         raise SystemExit(1)
...     site = zope.app.component.hooks.getSite()
...     site.worker_done = 1
>>> gocept.runner.runner.MainLoop(getRootFolder(), 0.1, worker)()
Working
Working

We have set the attribute worker_done now:

>>> getRootFolder().worker_done
1

When the worker produces an error, the transaction is aborted:

>>> work_count = 0
>>> def worker():
...     global work_count
...     work_count += 1
...     print "Working"
...     site = zope.app.component.hooks.getSite()
...     site.worker_done += 1
...     if work_count < 3:
...         raise ValueError('hurz')
...     raise SystemExit(1)
>>> gocept.runner.runner.MainLoop(getRootFolder(), 0.1, worker)()
Working
Working
Working

We still have the attribute worker_done set to 1:b

>>> getRootFolder().worker_done
1

Controlling sleep time

The worker function can control the sleep time[#log-handler]_

>>> work_count = 0
>>> def worker():
...     global work_count
...     work_count += 1
...     new_sleep = work_count * 0.1
...     if work_count == 3:
...         print "Will sleep default"
...         return None
...     if work_count > 3:
...         raise SystemExit(1)
...     print "Will sleep", new_sleep
...     return new_sleep
>>> gocept.runner.runner.MainLoop(getRootFolder(), 0.15, worker)()
Will sleep 0.1
Will sleep 0.2
Will sleep default

The real sleep values are in the log:

>>> print log.getvalue(),
new transaction
commit
Sleeping 0.1 seconds
new transaction
commit
Sleeping 0.2 seconds
new transaction
commit
Sleeping 0.15 seconds
new transaction
abort

[3]

Restore old log handler:

>>> logging.root.removeHandler(log_handler)
>>> logging.root.setLevel(old_log_level)

[2]

Register a log handler

>>> import logging
>>> import StringIO
>>> log = StringIO.StringIO()
>>> log_handler = logging.StreamHandler(log)
>>> logging.root.addHandler(log_handler)
>>> old_log_level = logging.root.level
>>> logging.root.setLevel(logging.DEBUG)

[3]

When an error occours within the worker, the default sleep time will be used:

>>> log.seek(0)
>>> log.truncate()
>>> work_count = 0
>>> def worker():
...     global work_count
...     work_count += 1
...     if work_count == 1:
...         new_sleep = 0.1
...     elif work_count == 2:
...         print "Failing"
...         raise Exception("Fail!")
...     elif work_count == 3:
...         print "Will sleep default"
...         return None
...     elif work_count > 3:
...         return gocept.runner.Exit
...     print "Will sleep", new_sleep
...     return new_sleep
>>> gocept.runner.runner.MainLoop(getRootFolder(), 0.15, worker)()
Will sleep 0.1
Failing
Will sleep default

The real sleep values are in the log:

>>> print log.getvalue(),
new transaction
commit
Sleeping 0.1 seconds
new transaction
Fail!
Traceback (most recent call last):
  ...
Exception: Fail!
abort
Sleeping 0.15 seconds
new transaction
commit
Sleeping 0.15 seconds
new transaction
commit

Changes

0.5 (2009-09-21)

• Does no longer use zope.app.twisted but zope.app.server instead.

0.4 (2009-09-03)

• The principal set by appmain/once can be computed by a function now.

0.3.2 (2009-05-21)

• Fixed handling of subsites in appmain.

0.3.1 (2009-05-21)

• Declared namespace package.

0.3 (2009-04-15)

• When a worker fails the default sleep time (instead of the last one) will be used.

0.2 (2009-04-09)

• Added a clean way to exit the runner (by returning gocept.runner.Exit).

0.1 (2009-04-07)

• first public release