[sonic-daemon-base] Create DaemonBase class for all daemons (#2570)

DaemonBase is to wrap the common function of daemons, such as logging,
signal handling, db connector, load specific platform plugins.

Signed-off-by: Kevin Wang <kevinw@mellanox.com>

rules/docker-platform-monitor.mk

@@ -7,6 +7,7 @@ $(DOCKER_PLATFORM_MONITOR)_PYTHON_DEBS += $(SONIC_LEDD) $(SONIC_XCVRD) $(SONIC_P
 $(DOCKER_PLATFORM_MONITOR)_PYTHON_WHEELS += $(SONIC_PLATFORM_COMMON_PY2)
 $(DOCKER_PLATFORM_MONITOR)_PYTHON_WHEELS += $(SWSSSDK_PY2)
 $(DOCKER_PLATFORM_MONITOR)_PYTHON_WHEELS += $(SONIC_PLATFORM_API_PY2)
+$(DOCKER_PLATFORM_MONITOR)_PYTHON_WHEELS += $(SONIC_DAEMON_BASE_PY2)
 $(DOCKER_PLATFORM_MONITOR)_LOAD_DOCKERS = $(DOCKER_CONFIG_ENGINE)
 
 SONIC_DOCKER_IMAGES += $(DOCKER_PLATFORM_MONITOR)

rules/sonic-daemon-base.mk

@@ -0,0 +1,7 @@
+# SONIC_DAEMON_BASE_PY2 package
+
+SONIC_DAEMON_BASE_PY2 = sonic_daemon_base-1.0-py2-none-any.whl
+$(SONIC_DAEMON_BASE_PY2)_SRC_PATH = $(SRC_PATH)/sonic-daemon-base
+$(SONIC_DAEMON_BASE_PY2)_PYTHON_VERSION = 2
+SONIC_PYTHON_WHEELS += $(SONIC_DAEMON_BASE_PY2)
+

src/sonic-daemon-base/setup.py

@@ -0,0 +1,30 @@
+from setuptools import setup
+
+setup(
+    name='sonic-daemon-base',
+    version='1.0',
+    description='Sonic daemon base package',
+    license='Apache 2.0',
+    author='SONiC Team',
+    author_email='linuxnetdev@microsoft.com',
+    url='https://github.com/Azure/sonic-platform-daemons',
+    maintainer='Kevin Wang',
+    maintainer_email='kevinw@mellanox.com',
+    packages=[
+        'sonic_daemon_base',
+    ],
+    classifiers=[
+        'Development Status :: 4 - Beta',
+        'Environment :: No Input/Output (Daemon)',
+        'Intended Audience :: Developers',
+        'Intended Audience :: Information Technology',
+        'Intended Audience :: System Administrators',
+        'License :: OSI Approved :: Apache Software License',
+        'Natural Language :: English',
+        'Operating System :: POSIX :: Linux',
+        'Programming Language :: Python :: 2.7',
+        'Topic :: System :: Hardware',
+    ],
+    keywords='SONiC sonic PLATFORM platform DAEMON daemon',
+)
+

src/sonic-daemon-base/sonic_daemon_base/daemon_base.py

@@ -0,0 +1,136 @@
+#!/usr/bin/env python2
+
+try:
+    import imp
+    import signal
+    import subprocess
+    import sys
+    import syslog
+    from swsscommon import swsscommon
+except ImportError, e:
+    raise ImportError (str(e) + " - required module not found")
+
+#============================= Constants =============================
+
+# Platform root directory inside docker
+PLATFORM_ROOT_DOCKER = "/usr/share/sonic/platform"
+SONIC_CFGGEN_PATH = '/usr/local/bin/sonic-cfggen'
+HWSKU_KEY = 'DEVICE_METADATA.localhost.hwsku'
+PLATFORM_KEY = 'DEVICE_METADATA.localhost.platform'
+
+class DaemonBase(object):
+    # Redis DB information
+    redis_hostname = "localhost"
+    redis_port = 6379
+    redis_timeout_msecs = 0
+
+    def __init__(self):
+        self.log_info("Starting up...")
+        # Register our signal handlers
+        signal.signal(signal.SIGHUP, self.signal_handler)
+        signal.signal(signal.SIGINT, self.signal_handler)
+        signal.signal(signal.SIGTERM, self.signal_handler)
+
+    def __del__(self):
+        self.log_error("Return from daemon, exiting...")
+
+    def run(self):
+        raise NotImplementedError()
+
+    # ========================== Connect to DB ============================
+    def db_connect(self, db):
+        return swsscommon.DBConnector(db,
+                                      self.redis_hostname,
+                                      self.redis_port,
+                                      self.redis_timeout_msecs)
+
+    # ========================== Syslog wrappers ==========================
+    def log_info(self, msg):
+        syslog.openlog()
+        syslog.syslog(syslog.LOG_INFO, msg)
+        syslog.closelog()
+
+    def log_warning(self, msg):
+        syslog.openlog()
+        syslog.syslog(syslog.LOG_WARNING, msg)
+        syslog.closelog()
+
+    def log_error(self, msg):
+        syslog.openlog()
+        syslog.syslog(syslog.LOG_ERR, msg)
+        syslog.closelog()
+
+    #========================== Signal Handling ==========================
+    def signal_handler(self, sig, frame):
+        if sig == signal.SIGHUP:
+            self.log_info("Caught SIGHUP - ignoring...")
+            return
+        elif sig == signal.SIGINT:
+            self.log_info("Caught SIGINT - exiting...")
+            sys.exit(128 + sig)
+        elif sig == signal.SIGTERM:
+            self.log_info("Caught SIGTERM - exiting...")
+            sys.exit(128 + sig)
+        else:
+            self.log_warning("Caught unhandled signal '" + sig + "'")
+            return
+
+    #============ Functions to load platform-specific classes ============
+    # Returns platform and HW SKU
+    def get_platform_and_hwsku(self):
+        try:
+            proc = subprocess.Popen([SONIC_CFGGEN_PATH, '-H', '-v', PLATFORM_KEY],
+                                    stdout=subprocess.PIPE,
+                                    shell=False,
+                                    stderr=subprocess.STDOUT)
+            stdout = proc.communicate()[0]
+            proc.wait()
+            platform = stdout.rstrip('\n')
+
+            proc = subprocess.Popen([SONIC_CFGGEN_PATH, '-d', '-v', HWSKU_KEY],
+                                    stdout=subprocess.PIPE,
+                                    shell=False,
+                                    stderr=subprocess.STDOUT)
+            stdout = proc.communicate()[0]
+            proc.wait()
+            hwsku = stdout.rstrip('\n')
+        except OSError, e:
+            self.log_error("Cannot to detect platform")
+            raise OSError("Cannot detect platform")
+
+        return (platform, hwsku)
+
+    # Returns path to hwsku
+    def get_path_to_platform_and_hwsku(self):
+        # Get platform and hwsku
+        (platform, hwsku) = self.get_platform_and_hwsku()
+
+        # Load platform module from source
+        platform_path = PLATFORM_ROOT_DOCKER
+        hwsku_path = "/".join([platform_path, hwsku])
+
+        return (platform_path, hwsku_path)
+
+    # Loads platform specific psuutil module from source
+    def load_platform_util(self, module_name, class_name):
+        platform_util = None
+
+        # Get path to platform and hwsku
+        (platform_path, hwsku_path) = self.get_path_to_platform_and_hwsku()
+
+        try:
+            module_file = "/".join([platform_path, "plugins", module_name + ".py"])
+            module = imp.load_source(module_name, module_file)
+        except IOError, e:
+            self.log_error("Failed to load platform module '%s': %s" % (module_name, str(e)))
+            return None
+
+        try:
+            platform_util_class = getattr(module, class_name)
+            platform_util = platform_util_class()
+        except AttributeError, e:
+            self.log_error("Failed to instantiate '%s' class: %s" % (class_name, str(e)))
+            return None
+
+        return platform_util
+