Update PackageCache Class to respect external logging configuration

[ameliendeshams]

Modify the _init_logging method in the PackageCache class of the package_cache.py module to check for the presence of the REZ_LOGGING_CONF environment variable. If this variable is set, use its value as a logging configuration file and return the configured logger object. This ensures that the custom logging setup can override the default "rez-pkg-cache" logger created by the PackageCache class.

Current code:

rez/src/rez/package_cache.py

Lines 841 to 876 in 4e00cfd

	def _init_logging(self):
	"""
	Creates logger that logs to file and stdout. Used for:
	- adding variants in daemonized proc;
	- clean(), which would typically be run as a cron, but can also be run
	manually (hence the logging to stdout also)
	"""
	logger = logging.getLogger("rez-pkg-cache")
	logger.setLevel(logging.INFO)
	logger.propagate = False
	logfilepath = os.path.join(self._log_dir, time.strftime("%Y-%m-%d.log"))
	handler1 = logging.FileHandler(logfilepath)
	handler2 = ColorizedStreamHandler()
	formatter = logging.Formatter(
	"%(name)s %(asctime)s PID-%(process)d %(levelname)s %(message)s")
	for h in (handler1, handler2):
	h.setFormatter(formatter)
	logger.addHandler(h)
	# delete old logfiles
	now = int(time.time())
	try:
	for name in os.listdir(self._log_dir):
	filepath = os.path.join(self._log_dir, name)
	st = os.stat(filepath)
	age_secs = now - int(st.st_ctime)
	age_days = age_secs / (3600 * 24)
	if age_days > config.package_cache_log_days:
	safe_remove(filepath)
	except:
	logger.exception("Failed to delete old logfiles")
	return logger

Suggestion:

def _init_logging(self):
    """
    Creates logger that logs to file and stdout. Used for:
    - adding variants in daemonized proc;
    - clean(), which would typically be run as a cron, but can also be run
      manually (hence the logging to stdout also)
    """
    logger = logging.getLogger("rez-pkg-cache")
    
    logging_conf = os.getenv("REZ_LOGGING_CONF")
    if logging_conf:
        logging.config.fileConfig(logging_conf, disable_existing_loggers=False)
        return logger
        
    logger.setLevel(logging.INFO)
    logger.propagate = False
    
    [...]

Motivation
Since the rez module has its own _init_logging function that implements custom logging functionality
with the environment variable REZ_LOGGING_CONF:

rez/src/rez/__init__.py

Lines 21 to 43 in 4e00cfd

	def _init_logging():
	logging_conf = os.getenv("REZ_LOGGING_CONF")
	if logging_conf:
	import logging.config
	logging.config.fileConfig(logging_conf, disable_existing_loggers=False)
	return
	import logging
	from rez.utils.colorize import ColorizedStreamHandler
	formatter = logging.Formatter(
	fmt="%(asctime)s %(levelname)-8s %(message)s",
	datefmt="%X"
	)
	handler = ColorizedStreamHandler(sys.stderr)
	handler.setFormatter(formatter)
	logger = logging.getLogger("rez")
	logger.propagate = False
	logger.setLevel(logging.DEBUG)
	logger.addHandler(handler)
	_init_logging()

It would be wise to implement the same feature in the _init_logging method of the PackageCache class.

For now, we've set up our own custom handlers on the logger "rez-pkg-cache", but there are still duplicate logs and no way to remove the handlers from "rez-pkg-cache".

Maintainer note:

There is an opportunity to reduce code duplication.

[JeanChristopheMorinPerso]

Relates to #542

[BryceGattis]

I'll take a look at this one for Dev Days 👍