Add implement of loading hostmonitor driver

This pathc adds implementation of loading hostmonitor driver
using stevedore.

Change-Id: I29666484b35cb5f295b0ab183e9bb3cbbcc28d21
Implements: bp pythonize-host-and-process-monitor

masakarimonitors/conf/__init__.py

@@ -15,6 +15,7 @@ from oslo_config import cfg
 
 from masakarimonitors.conf import api
 from masakarimonitors.conf import base
+from masakarimonitors.conf import host
 from masakarimonitors.conf import instance
 from masakarimonitors.conf import process
 from masakarimonitors.conf import service
@@ -23,6 +24,7 @@ CONF = cfg.CONF
 
 api.register_opts(CONF)
 base.register_opts(CONF)
+host.register_opts(CONF)
 instance.register_opts(CONF)
 process.register_opts(CONF)
 service.register_opts(CONF)

masakarimonitors/conf/host.py

@@ -0,0 +1,30 @@
+# Copyright(c) 2016 Nippon Telegraph and Telephone 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.
+from oslo_config import cfg
+
+monitor_host_opts = [
+    cfg.StrOpt('monitoring_driver',
+               default='default',
+               help='Driver that hostmonitor uses for monitoring hosts.'),
+]
+
+
+def register_opts(conf):
+    conf.register_opts(monitor_host_opts, group='host')
+
+
+def list_opts():
+    return {
+        'host': monitor_host_opts
+    }

masakarimonitors/hostmonitor/host.py

@@ -12,11 +12,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
+from stevedore import driver
+
 from oslo_log import log as oslo_logging
 
+import masakarimonitors.conf
+from masakarimonitors.i18n import _LE
 from masakarimonitors import manager
 
 LOG = oslo_logging.getLogger(__name__)
+CONF = masakarimonitors.conf.CONF
 
 
 class HostmonitorManager(manager.Manager):
@@ -25,8 +31,38 @@ class HostmonitorManager(manager.Manager):
     def __init__(self, *args, **kwargs):
         super(HostmonitorManager, self).__init__(
             service_name="hostmonitor", *args, **kwargs)
+        self.driver = None
+
+    def init_host(self):
+        """Initialization for hostmonitor."""
+        try:
+            # Determine dynamic load driver from configuration.
+            driver_name = CONF.host.monitoring_driver
+
+            # Load the driver to global.
+            self.driver = driver.DriverManager(
+                namespace='hostmonitor.driver',
+                name=driver_name,
+                invoke_on_load=True,
+                invoke_args=(),
+            )
+        except Exception as e:
+            LOG.exception(
+                _LE("Exception caught during initializing hostmonitor: %s"),
+                e)
+            os._exit(1)
+
+    def stop(self):
+        self.driver.driver.stop()
 
     def main(self):
         """Main method."""
 
-        pass
+        try:
+            # Call the host monitoring driver.
+            self.driver.driver.monitor_hosts()
+
+        except Exception as e:
+            LOG.exception(_LE("Exception caught: %s"), e)
+
+        return

masakarimonitors/hostmonitor/host_handler/driver.py

@@ -0,0 +1,32 @@
+# Copyright(c) 2016 Nippon Telegraph and Telephone 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.
+
+import abc
+import six
+
+
+@six.add_metaclass(abc.ABCMeta)
+class DriverBase(object):
+    """Driver Base class.
+
+    This class is base of monitoring hosts.
+    """
+
+    def __init__(self):
+        pass
+
+    @abc.abstractmethod
+    def monitor_hosts(self):
+        """Must override monitor_hosts method."""
+        pass

masakarimonitors/hostmonitor/host_handler/handle_host.py

@@ -0,0 +1,28 @@
+# Copyright(c) 2016 Nippon Telegraph and Telephone 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.
+
+import masakarimonitors.hostmonitor.host_handler.driver as driver
+
+
+class HandleHost(driver.DriverBase):
+    """Handle hosts.
+
+    This class handles the host status.
+    """
+
+    def __init__(self):
+        super(HandleHost, self).__init__()
+
+    def monitor_hosts(self):
+        pass

setup.cfg

@@ -46,6 +46,10 @@ console_scripts =
     masakari-processmonitor = masakarimonitors.cmd.processmonitor:main
     masakari-hostmonitor = masakarimonitors.cmd.hostmonitor:main
 
+hostmonitor.driver =
+    simple = masakarimonitors.hostmonitor.host_handler.handle_host:HandleHost
+    default = masakarimonitors.hostmonitor.host_handler.handle_host:HandleHost
+
 [build_sphinx]
 source-dir = doc/source
 build-dir = doc/build