add UDP protocol support for logger

When a syslog daemon fails and SysLogHandler cannot reconnect to
it, server processes (proxy, container, object, and more)
would start consuming 100 % CPU and stop responding to requests.
It is because the server process go into an infinite loop if they
fail to reconnect to /dev/log.
This problem happens only when using unix_sockets.

This change enables us to use syslog without unix_sockets and fixes bug 780025.

Change-Id: Ibcc99a1a148b1008036146bf3bd079a9be24982c

AUTHORS

@@ -78,3 +78,4 @@ Ye Jia Xu (xyj.asmy@gmail.com)
 Pete Zaitcev (zaitcev@kotori.zaitcev.us)
 Josh Kearney (josh@jk0.org)
 Vincent Untz (vuntz@suse.com)
+Tsuyuzaki Kota (tsuyuzaki.kota@lab.ntt.co.jp)

swift/common/middleware/proxy_logging.py

@@ -94,7 +94,8 @@ class ProxyLoggingMiddleware(object):
         self.app = app
         self.log_hdrs = conf.get('log_headers', 'no').lower() in TRUE_VALUES
         access_log_conf = {}
-        for key in ('log_facility', 'log_name', 'log_level'):
+        for key in ('log_facility', 'log_name', 'log_level', 'log_udp_host',
+                    'log_udp_port'):
             value = conf.get('access_' + key, conf.get(key, None))
             if value:
                 access_log_conf[key] = value

swift/common/utils.py

@@ -511,6 +511,8 @@ def get_logger(conf, name=None, log_to_console=False, log_route=None,
         log_facility = LOG_LOCAL0
         log_level = INFO
         log_name = swift
+        log_udp_host = (disabled)
+        log_udp_port = logging.handlers.SYSLOG_UDP_PORT
         log_statsd_host = (disabled)
         log_statsd_port = 8125
         log_statsd_default_sample_rate = 1
@@ -542,13 +544,19 @@ def get_logger(conf, name=None, log_to_console=False, log_route=None,
     # facility for this logger will be set by last call wins
     facility = getattr(SysLogHandler, conf.get('log_facility', 'LOG_LOCAL0'),
                        SysLogHandler.LOG_LOCAL0)
-    log_address = conf.get('log_address', '/dev/log')
-    try:
-        handler = SysLogHandler(address=log_address, facility=facility)
-    except socket.error, e:
-        if e.errno != errno.ENOTSOCK:  # Socket operation on non-socket
-            raise e
-        handler = SysLogHandler(facility=facility)
+    udp_host = conf.get('log_udp_host')
+    if udp_host:
+        udp_port = conf.get('log_udp_port', logging.handlers.SYSLOG_UDP_PORT)
+        handler = SysLogHandler(address=(udp_host, udp_port),
+                                facility=facility)
+    else:
+        log_address = conf.get('log_address', '/dev/log')
+        try:
+            handler = SysLogHandler(address=log_address, facility=facility)
+        except socket.error, e:
+            if e.errno != errno.ENOTSOCK:  # Socket operation on non-socket
+                raise e
+            handler = SysLogHandler(facility=facility)
     handler.setFormatter(formatter)
     logger.addHandler(handler)
     get_logger.handler4logger[logger] = handler

swift/proxy/server.py

@@ -1865,7 +1865,8 @@ class BaseApplication(object):
         if logger is None:
             self.logger = get_logger(conf, log_route='proxy-server')
             access_log_conf = {}
-            for key in ('log_facility', 'log_name', 'log_level'):
+            for key in ('log_facility', 'log_name', 'log_level',
+                        'log_udp_host', 'log_udp_port'):
                 value = conf.get('access_' + key, conf.get(key, None))
                 if value:
                     access_log_conf[key] = value