Add SysLogger for new implementation.

src/sonic-py-common/sonic_py_common/daemon_base.py

@@ -1,9 +1,21 @@
+import logging
 import signal
 import sys
+import syslog
 
 from . import device_info
 from .general import load_module_from_source
 from .logger import Logger
+from .syslogger import SysLogger
+
+# Mapping syslog priorities to SysLogger's priority.
+LOG_PRIORITY_MAP = {
+    syslog.LOG_ERR: logging.ERROR,
+    syslog.LOG_WARNING: logging.WARNING,
+    syslog.LOG_NOTICE: logging.INFO,
+    syslog.LOG_INFO: logging.INFO,
+    syslog.LOG_DEBUG: logging.DEBUG
+}
 
 #
 # Constants ====================================================================
@@ -21,6 +33,7 @@
 # Helper functions =============================================================
 #
 
+
 def db_connect(db_name, namespace=EMPTY_NAMESPACE):
     from swsscommon import swsscommon
     return swsscommon.DBConnector(db_name, REDIS_TIMEOUT_MSECS, True, namespace)
@@ -32,12 +45,17 @@ def db_connect(db_name, namespace=EMPTY_NAMESPACE):
 
 
 class DaemonBase(Logger):
-    def __init__(self, log_identifier):
-        super(DaemonBase, self).__init__(
-            log_identifier=log_identifier,
-            log_facility=Logger.LOG_FACILITY_DAEMON,
-            log_option=(Logger.LOG_OPTION_NDELAY | Logger.LOG_OPTION_PID)
-        )
+    def __init__(self, log_identifier, use_syslogger=False):
+        super().__init__()
+        self.use_syslogger = use_syslogger
+        if self.use_syslogger:
+            self.logger_instance = SysLogger(log_identifier)
+        else:
+            self.logger_instance = Logger(
+                log_identifier=log_identifier,
+                log_facility=Logger.LOG_FACILITY_DAEMON,
+                log_option=(Logger.LOG_OPTION_NDELAY | Logger.LOG_OPTION_PID)
+            )
 
         # Register our default signal handlers, unless the signal already has a
         # handler registered, most likely from a subclass implementation
@@ -48,6 +66,20 @@ def __init__(self, log_identifier):
         if not signal.getsignal(signal.SIGTERM):
             signal.signal(signal.SIGTERM, self.signal_handler)
 
+    def log(self, priority, msg, also_print_to_console=False):
+        if self._min_log_priority >= priority:
+            if self.use_syslogger:
+                # Using SysLogger.
+                logging_priority = LOG_PRIORITY_MAP.get(priority, logging.INFO)
+                self.logger_instance.log(logging_priority, msg)
+            else:
+                # Send message to syslog
+                self.logger_instance.log(priority, msg)
+
+            # Send message to console
+            if also_print_to_console:
+                print(msg)
+
     # Default signal handler; can be overridden by subclass
     def signal_handler(self, sig, frame):
         if sig == signal.SIGHUP:

src/sonic-py-common/sonic_py_common/syslogger.py

@@ -0,0 +1,60 @@
+import os
+import socket
+import sys
+import logging
+from logging.handlers import SysLogHandler
+
+
+class SysLogger:
+    """
+    SysLogger class for Python applications using SysLogHandler
+    """
+
+    DEFAULT_LOG_FACILITY = SysLogHandler.LOG_USER
+    DEFAULT_LOG_LEVEL = SysLogHandler.LOG_INFO
+
+    def __init__(self, log_identifier=None, log_facility=DEFAULT_LOG_FACILITY, log_level=DEFAULT_LOG_LEVEL):
+        if log_identifier is None:
+            log_identifier = os.path.basename(sys.argv[0])
+
+        # Initialize SysLogger
+        self.logger = logging.getLogger(log_identifier)
+        self.logger.setLevel(log_level)
+        handler = SysLogHandler(address="/dev/log", facility=log_facility, socktype=socket.SOCK_DGRAM)
+        formatter = logging.Formatter("%(name)s: %(message)s")
+        handler.setFormatter(formatter)
+        self.logger.addHandler(handler)
+
+        # Set the default minimum log priority to 'LOG_DEBUG'
+        self.set_min_log_priority('LOG_DEBUG')
+
+    def set_min_log_priority(self, priority):
+        """
+        Sets the minimum log priority level. All log messages
+        with a priority lower than this will not be logged
+        """
+        self._min_log_level = self.LOG_LEVEL_MAP[priority]
+
+    # Methods for logging messages
+    def log(self, priority, msg, also_print_to_console=False):
+        if log_level >= self._min_log_level:
+            self.logger.log(log_level, msg)
+
+        if also_print_to_console:
+            print(msg)
+
+    # Convenience methods
+    def log_error(self, msg, also_print_to_console=False):
+        self.log(logging.ERROR, msg, also_print_to_console)
+
+    def log_warning(self, msg, also_print_to_console=False):
+        self.log(logging.WARNING, msg, also_print_to_console)
+
+    def log_notice(self, msg, also_print_to_console=False):
+        self.log(logging.INFO, msg, also_print_to_console)
+
+    def log_info(self, msg, also_print_to_console=False):
+        self.log(logging.INFO, msg, also_print_to_console)
+
+    def log_debug(self, msg, also_print_to_console=False):
+        self.log(logging.DEBUG, msg, also_print_to_console)