Thread interface

azurelinuxagent/common/interfaces.py

@@ -0,0 +1,40 @@
+# Microsoft Azure Linux Agent
+#
+# Copyright 2020 Microsoft Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# Requires Python 2.6+ and Openssl 1.0+
+#
+
+
+class ThreadHandlerInterface(object):
+    """
+    Interface for all thread handlers created and maintained by the GuestAgent.
+    """
+
+    @staticmethod
+    def get_thread_name():
+        raise NotImplementedError("get_thread_name() not implemented")
+
+    def run(self):
+        raise NotImplementedError("run() not implemented")
+
+    def is_alive(self):
+        raise NotImplementedError("is_alive() not implemented")
+
+    def start(self):
+        raise NotImplementedError("start() not implemented")
+
+    def stop(self):
+        raise NotImplementedError("stop() not implemented")

azurelinuxagent/ga/env.py

@@ -28,6 +28,7 @@
 from azurelinuxagent.common.dhcp import get_dhcp_handler
 from azurelinuxagent.common.event import add_periodic, WALAEventOperation
 from azurelinuxagent.common.future import ustr
+from azurelinuxagent.common.interfaces import ThreadHandlerInterface
 from azurelinuxagent.common.osutil import get_osutil
 from azurelinuxagent.common.protocol.util import get_protocol_util
 from azurelinuxagent.common.utils.archive import StateArchiver
@@ -46,7 +47,7 @@ def get_env_handler():
     return EnvHandler()
 
 
-class EnvHandler(object): # pylint: disable=R0902
+class EnvHandler(ThreadHandlerInterface): # pylint: disable=R0902
     """
     Monitor changes to dhcp and hostname.
     If dhcp client process re-start has occurred, reset routes, dhcp with fabric.

azurelinuxagent/ga/extension_telemetry.py

@@ -29,6 +29,7 @@
     TELEMETRY_LOG_PROVIDER_ID, add_event, WALAEventOperation, add_log_event, get_event_logger
 from azurelinuxagent.common.exception import InvalidExtensionEventError
 from azurelinuxagent.common.future import ustr
+from azurelinuxagent.common.interfaces import ThreadHandlerInterface
 from azurelinuxagent.common.telemetryevent import TelemetryEventList, TelemetryEvent, TelemetryEventParam, \
     GuestAgentGenericLogsSchema
 from azurelinuxagent.ga.exthandlers import HANDLER_NAME_PATTERN
@@ -347,7 +348,7 @@ def add_common_params_to_extension_event(event, event_time):
         reporter.add_common_event_parameters(event, event_time)
 
 
-class ExtensionTelemetryHandler(object):
+class ExtensionTelemetryHandler(ThreadHandlerInterface):
     """
     This Handler takes care of fetching the Extension Telemetry events from the {extension_events_dir} and sends it to
     Kusto for advanced debuggability.

azurelinuxagent/ga/monitor.py

@@ -19,19 +19,18 @@
 import threading
 import uuid
 
-from azurelinuxagent.common.utils import textutil # pylint: disable=W0611
-
 import azurelinuxagent.common.logger as logger
 import azurelinuxagent.common.utils.networkutil as networkutil
 from azurelinuxagent.common.cgroupconfigurator import CGroupConfigurator
 from azurelinuxagent.common.cgroupstelemetry import CGroupsTelemetry
 from azurelinuxagent.common.errorstate import ErrorState
 from azurelinuxagent.common.event import add_event, WALAEventOperation, report_metric, collect_events
 from azurelinuxagent.common.future import ustr
+from azurelinuxagent.common.interfaces import ThreadHandlerInterface
 from azurelinuxagent.common.osutil import get_osutil
-from azurelinuxagent.common.protocol.util import get_protocol_util
 from azurelinuxagent.common.protocol.healthservice import HealthService
 from azurelinuxagent.common.protocol.imds import get_imds_client
+from azurelinuxagent.common.protocol.util import get_protocol_util
 from azurelinuxagent.common.utils.restutil import IOErrorCounter
 from azurelinuxagent.common.utils.textutil import hash_strings
 from azurelinuxagent.common.version import AGENT_NAME, CURRENT_VERSION
@@ -157,7 +156,7 @@ def _operation_impl(self):
             self.last_nic_state = nic_state
 
 
-class MonitorHandler(object): # pylint: disable=R0902
+class MonitorHandler(ThreadHandlerInterface): # pylint: disable=R0902
     # telemetry
     EVENT_COLLECTION_PERIOD = datetime.timedelta(minutes=1)
     # host plugin
@@ -225,7 +224,8 @@ def init_imds_client(self):
     def is_alive(self):
         return self.event_thread is not None and self.event_thread.is_alive()
 
-    def start(self, init_data=False):
+    # W0221: arguments-differ - This is a special case, we need to init_data only when run first time.
+    def start(self, init_data=False):   # pylint: disable=arguments-differ
         self.event_thread = threading.Thread(target=self.daemon, args=(init_data,))
         self.event_thread.setDaemon(True)
         self.event_thread.setName(self.get_thread_name())