Merge pull request #33 from rackerlabs/hardware_specific_os_install_device

RFR: Hardware-Specific OS Install Device

teeth_agent/agent.py

@@ -118,7 +118,7 @@ class TeethAgent(object):
         self.api = api.TeethAgentAPIServer(self)
         self.command_results = collections.OrderedDict()
         self.heartbeater = TeethAgentHeartbeater(self)
-        self.hardware = hardware.load_hardware_manager()
+        self.hardware = hardware.get_manager()
         self.command_lock = threading.Lock()
         self.log = structlog.get_logger()
         self.started_at = None
@@ -235,7 +235,7 @@ def build_agent(api_url,
     if not listen_host:
         listen_host = advertise_host
 
-    mac_addr = hardware.load_hardware_manager().get_primary_mac_address()
+    mac_addr = hardware.get_manager().get_primary_mac_address()
     api_client = overlord_agent_api.APIClient(api_url)
 
     log.info('fetching agent configuration from API',

teeth_agent/hardware.py

@@ -44,6 +44,10 @@ class HardwareManager(object):
     def get_primary_mac_address(self):
         pass
 
+    @abc.abstractmethod
+    def get_os_install_device(self):
+        pass
+
 
 class GenericHardwareManager(HardwareManager):
     def evaluate_hardware_support(cls):
@@ -52,6 +56,9 @@ class GenericHardwareManager(HardwareManager):
     def get_primary_mac_address(self):
         return open('/sys/class/net/eth0/address', 'r').read().strip('\n')
 
+    def get_os_install_device(self):
+        return '/dev/sda'
+
 
 def _compare_extensions(ext1, ext2):
     mgr1 = ext1.obj
@@ -59,20 +66,26 @@ def _compare_extensions(ext1, ext2):
     return mgr1.evaluate_hardware_support() - mgr2.evaluate_hardware_support()
 
 
-def load_hardware_manager():
-    log = structlog.get_logger()
-    extension_manager = stevedore.ExtensionManager(
-        namespace='teeth_agent.hardware_managers',
-        invoke_on_load=True)
+def get_manager():
+    global _global_manager
 
-    # There will always be at least one extension available (the
-    # GenericHardwareManager).
-    preferred_extension = sorted(extension_manager, _compare_extensions)[0]
-    preferred_manager = preferred_extension.obj
+    if not _global_manager:
+        log = structlog.get_logger()
+        extension_manager = stevedore.ExtensionManager(
+            namespace='teeth_agent.hardware_managers',
+            invoke_on_load=True)
 
-    if preferred_manager.evaluate_hardware_support() <= 0:
-        raise RuntimeError('No suitable HardwareManager could be found')
+        # There will always be at least one extension available (the
+        # GenericHardwareManager).
+        preferred_extension = sorted(extension_manager, _compare_extensions)[0]
+        preferred_manager = preferred_extension.obj
 
-    log.info('selected hardware manager',
-             manager_name=preferred_extension.entry_point_target)
-    return preferred_manager
+        if preferred_manager.evaluate_hardware_support() <= 0:
+            raise RuntimeError('No suitable HardwareManager could be found')
+
+        log.info('selected hardware manager',
+                 manager_name=preferred_extension.entry_point_target)
+
+        _global_manager = preferred_manager
+
+    return _global_manager

teeth_agent/standby.py

@@ -23,6 +23,7 @@ import requests
 from teeth_agent import base
 from teeth_agent import configdrive
 from teeth_agent import errors
+from teeth_agent import hardware
 
 
 def _configdrive_location():
@@ -114,7 +115,7 @@ class PrepareImageCommand(base.AsyncCommandResult):
         location = _configdrive_location()
         metadata = self.command_params['metadata']
         files = self.command_params['files']
-        device = '/dev/sda'
+        device = hardware.get_manager().get_os_install_device()
 
         _download_image(image_info)
         configdrive.write_configdrive(location, metadata, files)

teeth_agent/tests/hardware.py

@@ -25,7 +25,7 @@ class TestGenericHardwareManager(unittest.TestCase):
         self.hardware = hardware.GenericHardwareManager()
 
     @mock.patch('__builtin__.open')
-    def test_decom_mode(self, mocked_open):
+    def test_get_primary_mac_address(self, mocked_open):
         f = mocked_open.return_value
         f.read.return_value = '00:0c:29:8c:11:b1\n'
 
@@ -34,3 +34,6 @@ class TestGenericHardwareManager(unittest.TestCase):
 
         mocked_open.assert_called_once_with('/sys/class/net/eth0/address', 'r')
         f.read.assert_called_once_with()
+
+    def test_get_os_install_device(self):
+        self.assertEqual(self.hardware.get_os_install_device(), '/dev/sda')