Logging¶
Description
How to write log output from your Plone add-on program code
Introduction¶
Python logging package is used to log from Plone.
Log file location¶
By default, logs go to
var/log
folder under buildout.
If Zope instance is started in the foreground mode logs will be printed in the console (stdout).
Plone log filename varies depending on the installation mode (Zope, ZEO cluster). But for each instance there are two log files
- Event logs (errors), normally called instance.log
- HTTP request log (Apache compatible), normally called Z2.log
Viewing logs in real time¶
UNIX'y way for your terminal.
Open error log viewer using
tail
command (print content from file end) and wait for
further file writes
tail -f var/log/instance.log
Press CTRL+C to abort.
Logging from Python code¶
Example:
import logging
logger = logging.getLogger("Plone")
class MySomething(object):
...
def function(self):
logger.info("Reached function()")
...
Logging from page templates and RestrictedPython scripts¶
Python
logging
module doesn't provide Zope 2 security assertations and
does not work in
RestrictedPython Python scripts.
However, you can use
context.plone_log()
method logging in the sandboxed execution mode.
Example:
context.plone_log("This is so fun")
Forcing log level and output¶
The following snippet forces the log level of Python logging for the duration of the process by modifying the root logger object:
# Force application logging level to DEBUG and log output to stdout for all loggers
import sys, logging
root_logger = logging.getLogger()
root_logger.setLevel(logging.DEBUG)
handler = logging.StreamHandler(sys.stdout)
formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
handler.setFormatter(formatter)
root_logger.addHandler(handler)
Temporarily capturing log output¶
You can capture Python logging output temporarily to a string buffer. This is useful if you want to use logging module to record the status of long running operations and later show to the end user, who does not have access to file system logs, how the operation proceeded.
Below is an Grok view code example.
Example view code:
import logging
from StringIO import StringIO
from five import grok
from xxx.objects.interfaces import IXXXResearcher
from Products.CMFCore.interfaces import ISiteRoot
from Products.statusmessages.interfaces import IStatusMessage
from xxx.objects.sync import sync_with_xxx
grok.templatedir("templates")
logger = logging.getLogger("XXX sync")
class SyncAll(grok.View):
"""
Update all researcher data on the site from XXX (admin action)
"""
grok.context(ISiteRoot)
def sync(self):
"""
Search all objects of certain type on the site and
sync them with a remote site.
"""
brains = self.context.portal_catalog(object_provides=IXXXResearcher.__identifier__)
for brain in brains:
object = brain.getObject()
sync_with_xxx(object, force=True)
def startCapture(self, newLogLevel = None):
""" Start capturing log output to a string buffer.
http://docs.python.org/release/2.6/library/logging.html
@param newLogLevel: Optionally change the global logging level, e.g. logging.DEBUG
"""
self.buffer = StringIO()
print >> self.buffer, "Log output"
rootLogger = logging.getLogger()
if newLogLevel:
self.oldLogLevel = rootLogger.getEffectiveLevel()
rootLogger.setLevel(newLogLevel)
else:
self.oldLogLevel = None
self.logHandler = logging.StreamHandler(self.buffer)
formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
self.logHandler.setFormatter(formatter)
rootLogger.addHandler(self.logHandler)
def stopCapture(self):
""" Stop capturing log output.
@return: Collected log output as string
"""
# Remove our handler
rootLogger = logging.getLogger()
# Restore logging level (if any)
if self.oldLogLevel:
rootLogger.setLevel(self.oldLogLevel)
rootLogger.removeHandler(self.logHandler)
self.logHandler.flush()
self.buffer.flush()
return self.buffer.getvalue()
def update(self):
""" Process the form.
Process the form, log the output and show the output to the user.
"""
self.logs = None
if "sync-now" in self.request.form:
# Form button was pressed
# Open Plone status messages interface for this request
messages = IStatusMessage(self.request)
try:
self.startCapture(logging.DEBUG)
logger.info("Starting full site synchronization")
# Do the long running,
# lots of logging stuff
self.sync()
logger.info("Successfully done")
# It worked! Trolololo.
messages.addStatusMessage("Sync done")
except Exception, e:
# Show friendly error message
logger.exception(e)
messages.addStatusMessage(u"It did not work out:" + unicode(e))
finally:
# Put log output for the page template access
self.logs = self.stopCapture()
The related page template
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"
lang="en"
metal:use-macro="here/main_template/macros/master"
i18n:domain="xxx.objects">
<body>
<div metal:fill-slot="main">
<tal:main-macro metal:define-macro="main">
<h1 class="documentFirstHeading">
XXX site update
</h1>
<p class="documentDescription">
Update all researches from XXX
</p>
<div tal:condition="view/logs">
<p>Sync results:</p>
<pre tal:content="view/logs" />
</div>
<form action="@@syncall" method="POST">
<button type="submit" name="sync-now">
Sync now
</button>
</form>
</tal:main-macro>
</div>
</body>
</html>
transaction_note()¶
Leave a note on Zope's History tab.