add support for custom log handlers

Add a hook to get_logger to run custom functions to add custom log
handlers or the like.

Change-Id: Ib04b12939dcac7e4ad6453dea9795682044c6ae0

etc/account-server.conf-sample

@@ -13,6 +13,10 @@
 # log_facility = LOG_LOCAL0
 # log_level = INFO
 # log_address = /dev/log
+# comma separated list of functions to call to setup custom log handlers.
+# functions get passed: conf, name, log_to_console, log_route, fmt, logger,
+# adapted_logger
+# log_custom_handlers =
 # If set, log_udp_host will override log_address
 # log_udp_host =
 # log_udp_port = 514

etc/container-server.conf-sample

@@ -16,6 +16,10 @@
 # log_facility = LOG_LOCAL0
 # log_level = INFO
 # log_address = /dev/log
+# comma separated list of functions to call to setup custom log handlers.
+# functions get passed: conf, name, log_to_console, log_route, fmt, logger,
+# adapted_logger
+# log_custom_handlers =
 # If set, log_udp_host will override log_address
 # log_udp_host =
 # log_udp_port = 514

etc/object-expirer.conf-sample

@@ -6,6 +6,10 @@
 # log_facility = LOG_LOCAL0
 # log_level = INFO
 # log_address = /dev/log
+# comma separated list of functions to call to setup custom log handlers.
+# functions get passed: conf, name, log_to_console, log_route, fmt, logger,
+# adapted_logger
+# log_custom_handlers =
 # If set, log_udp_host will override log_address
 # log_udp_host =
 # log_udp_port = 514

etc/object-server.conf-sample

@@ -14,6 +14,10 @@
 # log_facility = LOG_LOCAL0
 # log_level = INFO
 # log_address = /dev/log
+# comma separated list of functions to call to setup custom log handlers.
+# functions get passed: conf, name, log_to_console, log_route, fmt, logger,
+# adapted_logger
+# log_custom_handlers =
 # If set, log_udp_host will override log_address
 # log_udp_host =
 # log_udp_port = 514

etc/proxy-server.conf-sample

@@ -15,6 +15,10 @@
 # log_level = INFO
 # log_headers = False
 # log_address = /dev/log
+# comma separated list of functions to call to setup custom log handlers.
+# functions get passed: conf, name, log_to_console, log_route, fmt, logger,
+# adapted_logger
+# log_custom_handlers =
 # If set, log_udp_host will override log_address
 # log_udp_host =
 # log_udp_port = 514

swift/common/utils.py

@@ -687,6 +687,20 @@ def get_logger(conf, name=None, log_to_console=False, log_route=None,
         logger.statsd_client = None
 
     adapted_logger = LogAdapter(logger, name)
+    other_handlers = conf.get('log_custom_handlers', None)
+    if other_handlers:
+        log_custom_handlers = [s.strip() for s in other_handlers.split(',')
+                               if s.strip()]
+        for hook in log_custom_handlers:
+            try:
+                mod, fnc = hook.rsplit('.', 1)
+                logger_hook = getattr(__import__(mod, fromlist=[fnc]), fnc)
+                logger_hook(conf, name, log_to_console, log_route, fmt,
+                            logger, adapted_logger)
+            except (AttributeError, ImportError):
+                print >>sys.stderr, 'Error calling custom handler [%s]' % hook
+            except ValueError:
+                print >>sys.stderr, 'Invalid custom handler format [%s]' % hook
     return adapted_logger