CherryPy Logging: How do I configure and use the global and application level loggers?

Question

Hello all. I'm having trouble with logging. I'm running CherryPy 3.2 and I've been reading through the docs here, but haven't found any examples of how to configure a local log file for output and how to write to it.

Raspberry.py:

import socket
import sys
import cherrypy

app_roots = {
                # Sean's laptop dev environment.
                "mylaptop": "/home/src/local-mydomain.com/py",

                # Hosted dev environment.  
                "mydomain.com" : "/home/dev/src/py"
            }


hostname = socket.gethostname()
CherryPyLog = cherrypy.tree.mount().log

if hostname not in app_roots:
    CherryPyLog("The following hostname does not have an app_root entry in raspberry.py.  Exiting early.")
    sys.exit()

sys.stdout = sys.stderr
sys.path.append(app_roots[hostname])

import os
os.chdir(app_root)

# Setup for raspberry application logging.
import datetime
today = datetime.datetime.today()
log.access_file = "{0}/{1}.raspberry.access.log".format(app_roots[hostname],today.strftime("%Y%m%d-%H%M"))
log.error_file = "{0}/{1}.raspberry.error.log".format(app_roots[hostname],today.strftime("%Y%m%d-%H%M"))

#Testing logger
log("{0} -- Logger configured".format(today.strftime("%Y%m%d-%H%M%S")))

import atexit
cherrypy.config.update({'environment': 'embedded'})

if cherrypy.__version__.startswith('3.0') and cherrypy.engine.state == 0:
    cherrypy.engine.start(blocking = False)
    atexit.register(cherrypy.engine.stop)

from web.controllers.root import RaspberryRequestHandler

application = cherrypy.Application(RaspberryRequestHandler(), script_name = None, config = None)

UPDATE: Here's the code block that I ended up going with.

app_roots = {
                # Sean's laptop dev environment.
                "mylaptop": "/home/src/local-plottools.com/py",

                # Hosted dev environment.  
                "myDomain" : "/home/dev/src/py"
            }

import socket
hostname = socket.gethostname()

import cherrypy
import sys
if hostname not in app_roots:
    cherrypy.log("The hostname {0} does not have an app_root entry in {1}.  Exiting early.".format(hostname,__file__))
    sys.exit()

sys.stdout = sys.stderr
sys.path.append(app_roots[hostname])

import os
os.chdir(app_roots[hostname])

from web.controllers.root import RaspberryRequestHandler

cherrypy.config.update({
    'log.access_file': "{0}/cherrypy-access.log".format(app_roots[hostname]),
    'log.error_file': "{0}/cherrypy.log".format(app_roots[hostname]),
    "server.thread_pool" : 10
})

# special case, handling debug sessions when quickstart is needed.
if __name__ == "__main__":

    cherrypy.config.update({
                                'log.screen': True, 
                                "server.socket_port": 8000
                            })
    cherrypy.quickstart(RaspberryRequestHandler())
    sys.exit()

# This configuration is needed for running under mod_wsgi.  See here:  http://tools.cherrypy.org/wiki/ModWSGI    
cherrypy.config.update({'environment': 'embedded'})

applicationLogName = "{0}/raspberry.log".format(app_roots[hostname])

from logging import handlers
applicationLogFileHandler = handlers.RotatingFileHandler(applicationLogName, 'a', 10000000, 1000)

import logging
applicationLogFileHandler.setLevel(logging.DEBUG)

from cherrypy import _cplogging
applicationLogFileHandler.setFormatter(_cplogging.logfmt)

cherrypy.log.error_log.addHandler(applicationLogFileHandler)

application = cherrypy.Application(RaspberryRequestHandler(), None)

Answer 1

Simplifying a bit:

import os
import socket
import sys

import cherrypy

app_roots = {
                # Sean's laptop dev environment.
                "mylaptop": "/home/src/local-mydomain.com/py",

                # Hosted dev environment.  
                "mydomain.com" : "/home/dev/src/py"
            }


hostname = socket.gethostname()
if hostname not in app_roots:
    cherrypy.log("The hostname %r does not have an app_root entry in "
                 "raspberry.py.  Exiting early." % hostname)
    sys.exit()

sys.path.append(app_roots[hostname])
os.chdir(app_root)

cherrypy.config.update({
    'environment': 'embedded',
    'log.access_file': "{0}/raspberry.access.log".format(app_roots[hostname]),
    'log.error_file': "{0}/raspberry.error.log".format(app_roots[hostname]),
    })

from web.controllers.root import RaspberryRequestHandler
application = cherrypy.tree.mount(RaspberryRequestHandler(), '/')
# Insert log changes here
cherrypy.engine.start()

If you want different logs per day, use a RotatingFileHandler as described at http://www.cherrypy.org/wiki/Logging#CustomHandlers The important point I think you're missing is that you should muck about with app.log only after you've instantiated your app (e.g. via tree.mount(), as above), but before engine.start. That is, for the error log:

application = cherrypy.tree.mount(RaspberryRequestHandler(), '/')

log = application.log
log.error_file = ""

# Make a new RotatingFileHandler for the error log.
fname = "{0}/raspberry.error.log".format(app_roots[hostname])
h = handlers.RotatingFileHandler(fname, 'a', 10000000, 1000)
h.setLevel(DEBUG)
h.setFormatter(_cplogging.logfmt)
log.error_log.addHandler(h)

cherrypy.engine.start()

Hope that helps...