[Freeipa-devel] Logging changes in master

[John Dennis]

A few days ago changes were checked into the master branch to improve 
the way logging works. The modules ipapython.ipa_log_manager and 
ipapython.log_manager were added and contain extensive documentation 
(links to their HTML version appear below). But you don't need to read 
through it all, you just need to know a few basic facts for all code 
going forward, items 1-3 are mandatory to know, the rest are helpful.

1) Never import the Python logging module, instead:

from ipapython.log_manager import *

2) Use of the global root logger has been replaced, instead of 
logging.debug() use root_logger.debug(), etc.

3) Stand-alone programs should set up logging via this common utility, 
standard_logging_setup()

4) You can now control which classes (e.g. loggers) emit debug messages, 
it's no longer an all or nothing proposition, you can turn on debugging 
for just the code you're working on (or other level messages). Just edit 
one of the config files read by Env() and add a line like this:

log_logger_debug = comma separated list of regular expressions

where each regular expression matches a class (logger) name(s)

See IPALogManger.configure_from_env for details

5) The Env() config files now support the verbose flag to turn on info 
level messages.

6) Avoid use of the global root logger if possible, instead use a logger 
belonging to the logical code location.

If you have a class it's as simple as:

     log_mgr.get_logger(self, True)

Now you're class will have .debug(), .info() etc. methods bound to it 
and when you log your class name (or other name) will be visible (this 
happens automatically for all plugins).

If you don't have a class to hang your logger on use a meaningful name 
and create one, e.g.:

     logger = log_mgr.get_logger('client_installer')

     -or-

     logger = log_mgr.get_logger(os.path.basename(sys.argv[0]))

HTML versions of the documentation can be found here:

http://jdennis.fedorapeople.org/log_manager_doc/

-- 
John Dennis <jdennis at redhat.com>

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