Add a plugin interface for drivers

This change adds a plugin interface so that driver can be loaded dynamically.
Instead of importing each driver in the launcher, provider_manager and config,
the Drivers class discovers and loads driver from the driver directory.

This change also adds a reset() method to the driver Config interface to
reset the os_client_config reference when reloading the OpenStack driver.

Change-Id: Ia347aa2501de0e05b2a7dd014c4daf1b0a4e0fb5

nodepool/config.py

@@ -21,8 +21,7 @@ import yaml
 
 from nodepool import zk
 from nodepool.driver import ConfigValue
-from nodepool.driver.fake.config import FakeProviderConfig
+from nodepool.driver import Drivers
-from nodepool.driver.openstack.config import OpenStackProviderConfig
 
 
 class Config(ConfigValue):
@@ -59,10 +58,8 @@ def get_provider_config(provider):
     # Ensure legacy configuration still works when using fake cloud
     if provider.get('name', '').startswith('fake'):
         provider['driver'] = 'fake'
-    if provider['driver'] == 'fake':
+    driver = Drivers.get(provider['driver'])
-        return FakeProviderConfig(provider)
+    return driver['config'](provider)
-    elif provider['driver'] == 'openstack':
-        return OpenStackProviderConfig(provider)
 
 
 def openConfig(path):
@@ -90,8 +87,9 @@ def openConfig(path):
 def loadConfig(config_path):
     config = openConfig(config_path)
 
-    # Reset the shared os_client_config instance
+    # Call driver config reset now to clean global hooks like os_client_config
-    OpenStackProviderConfig.os_client_config = None
+    for driver in Drivers.drivers.values():
+        driver["config"].reset()
 
     newconfig = Config()
     newconfig.db = None

nodepool/driver/__init__.py

@@ -16,6 +16,10 @@
 # limitations under the License.
 
 import abc
+import inspect
+import importlib
+import logging
+import os
 
 import six
 
@@ -23,6 +27,79 @@ from nodepool import zk
 from nodepool import exceptions
 
 
+class Drivers:
+    """The Drivers plugin interface"""
+
+    log = logging.getLogger("nodepool.driver.Drivers")
+    drivers = {}
+    drivers_paths = None
+
+    @staticmethod
+    def _load_class(driver_name, path, parent_class):
+        """Return a driver class that implements the parent_class"""
+        spec = importlib.util.spec_from_file_location(driver_name, path)
+        module = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(module)
+        obj = inspect.getmembers(
+            module,
+            lambda x: inspect.isclass(x) and issubclass(x, parent_class) and
+            x.__module__ == driver_name)
+        error = None
+        if len(obj) > 1:
+            error = "multiple %s implementation" % parent_class
+        if not obj:
+            error = "no %s implementation found" % parent_class
+        if error:
+            Drivers.log.error("%s: %s" % (path, error))
+            return False
+        return obj[0][1]
+
+    @staticmethod
+    def load(drivers_paths=[]):
+        """Load drivers"""
+        if drivers_paths == Drivers.drivers_paths:
+            # Already loaded
+            return
+        Drivers.drivers.clear()
+        for drivers_path in drivers_paths + [os.path.dirname(__file__)]:
+            drivers = os.listdir(drivers_path)
+            for driver in drivers:
+                driver_path = os.path.join(drivers_path, driver)
+                if driver in Drivers.drivers:
+                    Drivers.log.warning("%s: duplicate driver" % driver_path)
+                    continue
+                if not os.path.isdir(driver_path) or \
+                   "__init__.py" not in os.listdir(driver_path):
+                    continue
+                Drivers.log.debug("%s: loading driver" % driver_path)
+                driver_obj = {}
+                for name, parent_class in (
+                        ("config", ProviderConfig),
+                        ("handler", NodeRequestHandler),
+                        ("provider", Provider),
+                ):
+                    driver_obj[name] = Drivers._load_class(
+                        driver, os.path.join(driver_path, "%s.py" % name),
+                        parent_class)
+                    if not driver_obj[name]:
+                        break
+                if not driver_obj[name]:
+                    Drivers.log.error("%s: skipping incorrect driver" %
+                                      driver_path)
+                    continue
+                Drivers.drivers[driver] = driver_obj
+        Drivers.drivers_paths = drivers_paths
+
+    @staticmethod
+    def get(name):
+        if not Drivers.drivers:
+            Drivers.load()
+        try:
+            return Drivers.drivers[name]
+        except KeyError:
+            raise RuntimeError("%s: unknown driver" % name)
+
+
 @six.add_metaclass(abc.ABCMeta)
 class Provider(object):
     """The Provider interface
@@ -353,6 +430,10 @@ class ProviderConfig(ConfigValue):
     def __eq__(self, other):
         pass
 
+    @abc.abstractmethod
+    def reset():
+        pass
+
     @abc.abstractmethod
     def load(self, newconfig):
         pass

nodepool/driver/fake/provider.py

@@ -66,13 +66,13 @@ class Dummy(object):
         setattr(self, key, value)
 
 
-def get_fake_quota():
-    return 100, 20, 1000000
-
-
 class FakeOpenStackCloud(object):
     log = logging.getLogger("nodepool.FakeOpenStackCloud")
 
+    @staticmethod
+    def _get_quota():
+        return 100, 20, 1000000
+
     def __init__(self, images=None, networks=None):
         self.pause_creates = False
         self._image_list = images
@@ -100,7 +100,8 @@ class FakeOpenStackCloud(object):
                   vcpus=4),
         ]
         self._server_list = []
-        self.max_cores, self.max_instances, self.max_ram = get_fake_quota()
+        self.max_cores, self.max_instances, self.max_ram = FakeOpenStackCloud.\
+            _get_quota()
 
     def _get(self, name_or_id, instance_list):
         self.log.debug("Get %s in %s" % (name_or_id, repr(instance_list)))
@@ -287,9 +288,11 @@ class FakeUploadFailCloud(FakeOpenStackCloud):
 
 
 class FakeProvider(OpenStackProvider):
+    fake_cloud = FakeOpenStackCloud
+
     def __init__(self, provider, use_taskmanager):
         self.createServer_fails = 0
-        self.__client = FakeOpenStackCloud()
+        self.__client = FakeProvider.fake_cloud()
         super(FakeProvider, self).__init__(provider, use_taskmanager)
 
     def _getClient(self):

nodepool/driver/openstack/config.py

@@ -96,6 +96,10 @@ class OpenStackProviderConfig(ProviderConfig):
                 cloud_kwargs[arg] = self.provider[arg]
         return cloud_kwargs
 
+    @staticmethod
+    def reset():
+        OpenStackProviderConfig.os_client_config = None
+
     def load(self, config):
         if OpenStackProviderConfig.os_client_config is None:
             OpenStackProviderConfig.os_client_config = \

nodepool/launcher.py

@@ -28,8 +28,7 @@ from nodepool import provider_manager
 from nodepool import stats
 from nodepool import config as nodepool_config
 from nodepool import zk
-from nodepool.driver.fake.handler import FakeNodeRequestHandler
+from nodepool.driver import Drivers
-from nodepool.driver.openstack.handler import OpenStackNodeRequestHandler
 
 
 MINS = 60
@@ -146,12 +145,8 @@ class PoolWorker(threading.Thread):
     # ---------------------------------------------------------------
 
     def _get_node_request_handler(self, provider, request):
-        if provider.driver.name == 'fake':
+        driver = Drivers.get(provider.driver.name)
-            return FakeNodeRequestHandler(self, request)
+        return driver['handler'](self, request)
-        elif provider.driver.name == 'openstack':
-            return OpenStackNodeRequestHandler(self, request)
-        else:
-            raise RuntimeError("Unknown provider driver %s" % provider.driver)
 
     def _assignHandlers(self):
         '''

nodepool/provider_manager.py

@@ -18,17 +18,12 @@
 
 import logging
 
-from nodepool.driver.fake.provider import FakeProvider
+from nodepool.driver import Drivers
-from nodepool.driver.openstack.provider import OpenStackProvider
 
 
 def get_provider(provider, use_taskmanager):
-    if provider.driver.name == 'fake':
+    driver = Drivers.get(provider.driver.name)
-        return FakeProvider(provider, use_taskmanager)
+    return driver['provider'](provider, use_taskmanager)
-    elif provider.driver.name == 'openstack':
-        return OpenStackProvider(provider, use_taskmanager)
-    else:
-        raise RuntimeError("Unknown provider driver %s" % provider.driver)
 
 
 class ProviderManager(object):

nodepool/tests/fixtures/drivers/test/config.py

@@ -0,0 +1,46 @@
+# Copyright 2017 Red Hat
+#
+# 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 voluptuous as v
+
+from nodepool.driver import ConfigValue
+from nodepool.driver import ProviderConfig
+
+
+class TestPool(ConfigValue):
+    pass
+
+
+class TestConfig(ProviderConfig):
+    def __eq__(self, other):
+        return self.name == other.name
+
+    @staticmethod
+    def reset():
+        pass
+
+    def load(self, newconfig):
+        self.pools = {}
+        for pool in self.provider.get('pools', []):
+            testpool = TestPool()
+            testpool.name = pool['name']
+            testpool.provider = self
+            for label in pool['labels']:
+                newconfig.labels[label].pools.append(testpool)
+            self.pools[pool['name']] = testpool
+
+    def get_schema(self):
+        pool = {'name': str,
+                'labels': [str]}
+        return v.Schema({'pools': [pool]})

nodepool/tests/fixtures/drivers/test/handler.py

@@ -0,0 +1,34 @@
+# Copyright 2017 Red Hat
+#
+# 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 logging
+
+from nodepool import zk
+from nodepool.driver import NodeRequestHandler
+
+
+class TestHandler(NodeRequestHandler):
+    log = logging.getLogger("nodepool.driver.test.TestHandler")
+
+    def run_handler(self):
+        self._setFromPoolWorker()
+        node = zk.Node()
+        node.state = zk.READY
+        node.external_id = "test-%s" % self.request.id
+        node.provider = self.provider.name
+        node.launcher = self.launcher_id
+        node.allocated_to = self.request.id
+        node.type = self.request.node_types[0]
+        self.nodeset.append(node)
+        self.zk.storeNode(node)

nodepool/tests/fixtures/drivers/test/provider.py

@@ -0,0 +1,46 @@
+# Copyright (C) 2011-2013 OpenStack Foundation
+#
+# 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 nodepool.driver import Provider
+
+
+class TestProvider(Provider):
+    def __init__(self, provider, *args):
+        self.provider = provider
+
+    def start(self):
+        pass
+
+    def stop(self):
+        pass
+
+    def join(self):
+        pass
+
+    def labelReady(self, name):
+        return True
+
+    def cleanupNode(self, node_id):
+        pass
+
+    def waitForNodeCleanup(self, node_id):
+        pass
+
+    def cleanupLeakedResources(self):
+        pass
+
+    def listNodes(self):
+        return []

nodepool/tests/fixtures/external_driver.yaml

@@ -0,0 +1,16 @@
+zookeeper-servers:
+  - host: {zookeeper_host}
+    port: {zookeeper_port}
+    chroot: {zookeeper_chroot}
+
+labels:
+  - name: test-label
+    min-ready: 1
+
+providers:
+  - name: test-provider
+    driver: test
+    pools:
+      - name: test-pool
+        labels:
+          - test-label

nodepool/tests/test_builder.py

@@ -18,6 +18,7 @@ import uuid
 import fixtures
 
 from nodepool import builder, exceptions, tests
+from nodepool.driver import Drivers
 from nodepool.driver.fake import provider as fakeprovider
 from nodepool import zk
 
@@ -119,8 +120,8 @@ class TestNodePoolBuilder(tests.DBTestCase):
         def get_fake_client(*args, **kwargs):
             return fake_client
 
-        self.useFixture(fixtures.MonkeyPatch(
+        self.useFixture(fixtures.MockPatchObject(
-            'nodepool.driver.fake.provider.FakeProvider._getClient',
+            Drivers.get('fake')['provider'], '_getClient',
             get_fake_client))
 
         configfile = self.setup_config('node.yaml')

nodepool/tests/test_drivers.py

@@ -0,0 +1,39 @@
+#
+# 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 os
+
+from nodepool import config as nodepool_config
+from nodepool import tests
+from nodepool.driver import Drivers
+
+
+class TestDrivers(tests.DBTestCase):
+    def setup_config(self, filename):
+        drivers_dir = os.path.join(
+            os.path.dirname(__file__), 'fixtures', 'drivers')
+        Drivers.load([drivers_dir])
+        return super().setup_config(filename)
+
+    def test_external_driver_config(self):
+        configfile = self.setup_config('external_driver.yaml')
+        nodepool_config.loadConfig(configfile)
+        self.assertIn("config", Drivers.get("test"))
+
+    def test_external_driver_handler(self):
+        configfile = self.setup_config('external_driver.yaml')
+        pool = self.useNodepool(configfile, watermark_sleep=1)
+        pool.start()
+        nodes = self.waitForNodes('test-label')
+        self.assertEqual(len(nodes), 1)

nodepool/tests/test_launcher.py

@@ -17,10 +17,10 @@ import logging
 import math
 import time
 import fixtures
-import unittest.mock as mock
 
 from nodepool import tests
 from nodepool import zk
+from nodepool.driver import Drivers
 import nodepool.launcher
 
 
@@ -111,8 +111,7 @@ class TestLauncher(tests.DBTestCase):
         self.assertEqual(nodes[2].type, 'fake-label4')
         self.assertEqual(nodes[3].type, 'fake-label2')
 
-    @mock.patch('nodepool.driver.fake.provider.get_fake_quota')
+    def _test_node_assignment_at_quota(self,
-    def _test_node_assignment_at_quota(self, mock_quota,
                                        config='node_quota.yaml',
                                        max_cores=100,
                                        max_instances=20,
@@ -124,7 +123,12 @@ class TestLauncher(tests.DBTestCase):
         '''
 
         # patch the cloud with requested quota
-        mock_quota.return_value = (max_cores, max_instances, max_ram)
+        def fake_get_quota():
+            return (max_cores, max_instances, max_ram)
+        self.useFixture(fixtures.MockPatchObject(
+            Drivers.get('fake')['provider'].fake_cloud, '_get_quota',
+            fake_get_quota
+        ))
 
         configfile = self.setup_config(config)
         self.useBuilder(configfile)
@@ -258,9 +262,7 @@ class TestLauncher(tests.DBTestCase):
                                             max_instances=math.inf,
                                             max_ram=2 * 8192)
 
-    @mock.patch('nodepool.driver.fake.provider.get_fake_quota')
+    def test_over_quota(self, config='node_quota_cloud.yaml'):
-    def test_over_quota(self, mock_quota,
-                        config='node_quota_cloud.yaml'):
         '''
         This tests what happens when a cloud unexpectedly returns an
         over-quota error.
@@ -272,7 +274,12 @@ class TestLauncher(tests.DBTestCase):
         max_ram = math.inf
 
         # patch the cloud with requested quota
-        mock_quota.return_value = (max_cores, max_instances, max_ram)
+        def fake_get_quota():
+            return (max_cores, max_instances, max_ram)
+        self.useFixture(fixtures.MockPatchObject(
+            Drivers.get('fake')['provider'].fake_cloud, '_get_quota',
+            fake_get_quota
+        ))
 
         configfile = self.setup_config(config)
         self.useBuilder(configfile)
@@ -589,8 +596,8 @@ class TestLauncher(tests.DBTestCase):
         def fail_delete(self, name):
             raise RuntimeError('Fake Error')
 
-        fake_delete = 'nodepool.driver.fake.provider.FakeProvider.deleteServer'
+        self.useFixture(fixtures.MockPatchObject(
-        self.useFixture(fixtures.MonkeyPatch(fake_delete, fail_delete))
+            Drivers.get('fake')['provider'], 'deleteServer', fail_delete))
 
         configfile = self.setup_config('node.yaml')
         pool = self.useNodepool(configfile, watermark_sleep=1)