Implement generation of shared secret for metadata

The ``nova-compute`` charm gates enablement of the local Nova
metadata service on presence of the ``metadata-shared-secret``
key in the relation data in the subordinate relation with
``neutron-plugin`` interface.  This is implemented in the classic
``neutron-openvswitch`` charm today.

Add the bits necessary for a reactive charm to participate in this
part of the relation.

Also adds units tests to the interface.

Change-Id: I358e60c40a7f7c0cd33b31f2b7a8c58d6cb83326

.gitignore

@@ -7,3 +7,4 @@ tags
 *.pyc
 .unit-state.db
 .local
+.stestr

.stestr.conf

@@ -0,0 +1,3 @@
+[DEFAULT]
+test_path=./unit_tests
+top_dir=./

interface.yaml

@@ -1,3 +1,11 @@
 name: neutron-plugin
 summary: Interface for intergrating Neutron SDN's with the nova-compute charm
-maintainer: James Page <james.page@ubuntu.com>
+maintainer: OpenStack Charmers <openstack-discuss@lists.openstack.org>
+repo: https://opendev.org/openstack/charm-interface-neutron-plugin.git
+ignore:
+  - 'unit_tests'
+  - '.stestr.conf'
+  - 'test-requirements.txt'
+  - 'tox.ini'
+  - '.gitignore'
+  - '.zuul.yaml'

provides.py

@@ -1,10 +1,14 @@
 import json
+import uuid
 
 from charms.reactive import hook
 from charms.reactive import RelationBase
 from charms.reactive import scopes
 
 
+METADATA_KEY = 'metadata-shared-secret'
+
+
 class NeutronPluginProvides(RelationBase):
     scope = scopes.GLOBAL
 
@@ -23,3 +27,25 @@ class NeutronPluginProvides(RelationBase):
             'subordinate_configuration': json.dumps(config),
         }
         conversation.set_remote(**relation_info)
+
+    def get_or_create_shared_secret(self):
+        """Retrieves a shared secret from local unit storage.
+
+        The secret is created if it does not already exist.
+
+        :returns: Shared secret
+        :rtype: str
+        """
+        secret = self.get_local(METADATA_KEY)
+        if secret is None:
+            secret = str(uuid.uuid4())
+            self.set_local(METADATA_KEY, secret)
+        return secret
+
+    def publish_shared_secret(self):
+        """Publish the shared secret on the relation."""
+        conversation = self.conversation()
+        relation_info = {
+            METADATA_KEY: self.get_or_create_shared_secret(),
+        }
+        conversation.set_remote(**relation_info)

test-requirements.txt

@@ -1,2 +1,5 @@
+charms.reactive
 flake8>=2.2.4,<=2.4.1
+mock
 os-testr>=0.4.1
+git+https://github.com/openstack/charms.openstack.git#egg=charms.openstack

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = pep8,py34,py35
+envlist = pep8,py3
 skipsdist = True
 # NOTE(beisner): Avoid build/test env pollution by not enabling sitepackages.
 sitepackages = False
@@ -13,17 +13,21 @@ install_command =
   pip install {opts} {packages}
 commands = ostestr {posargs}
 
-[testenv:py34]
-basepython = python3.4
+[testenv:py3]
+basepython = python3
 deps = -r{toxinidir}/test-requirements.txt
-# TODO: Need to write unit tests then remove the following command.
-commands = /bin/true
 
 [testenv:py35]
 basepython = python3.5
 deps = -r{toxinidir}/test-requirements.txt
-# TODO: Need to write unit tests then remove the following command.
-commands = /bin/true
+
+[testenv:py36]
+basepython = python3.6
+deps = -r{toxinidir}/test-requirements.txt
+
+[testenv:py37]
+basepython = python3.7
+deps = -r{toxinidir}/test-requirements.txt
 
 [testenv:pep8]
 basepython = python3

unit_tests/__init__.py

@@ -0,0 +1,17 @@
+# Copyright 2019 Canonical Ltd
+#
+# 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 charms_openstack.test_mocks
+
+
+charms_openstack.test_mocks.mock_charmhelpers()

unit_tests/test_provides.py

@@ -0,0 +1,157 @@
+# Copyright 2019 Canonical Ltd
+#
+# 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 json
+import mock
+
+import charms_openstack.test_utils as test_utils
+
+import provides
+
+
+_hook_args = {}
+
+
+def mock_hook(*args, **kwargs):
+
+    def inner(f):
+        # remember what we were passed.  Note that we can't actually determine
+        # the class we're attached to, as the decorator only gets the function.
+        _hook_args[f.__name__] = dict(args=args, kwargs=kwargs)
+        return f
+    return inner
+
+
+class TestNeutronPluginProvides(test_utils.PatchHelper):
+
+    @classmethod
+    def setUpClass(cls):
+        cls._patched_hook = mock.patch('charms.reactive.hook', mock_hook)
+        cls._patched_hook_started = cls._patched_hook.start()
+        # force providesto rerun the mock_hook decorator:
+        # try except is Python2/Python3 compatibility as Python3 has moved
+        # reload to importlib.
+        try:
+            reload(provides)
+        except NameError:
+            import importlib
+            importlib.reload(provides)
+
+    @classmethod
+    def tearDownClass(cls):
+        cls._patched_hook.stop()
+        cls._patched_hook_started = None
+        cls._patched_hook = None
+        # and fix any breakage we did to the module
+        try:
+            reload(provides)
+        except NameError:
+            import importlib
+            importlib.reload(provides)
+
+    def setUp(self):
+        self._patches = {}
+        self._patches_start = {}
+        conversation = mock.MagicMock()
+        self.target = provides.NeutronPluginProvides(
+            'some-relation', [conversation])
+
+    def tearDown(self):
+        self.target = None
+        for k, v in self._patches.items():
+            v.stop()
+            setattr(self, k, None)
+        self._patches = None
+        self._patches_start = None
+
+    def patch_target(self, attr, return_value=None):
+        mocked = mock.patch.object(self.target, attr)
+        self._patches[attr] = mocked
+        started = mocked.start()
+        started.return_value = return_value
+        self._patches_start[attr] = started
+        setattr(self, attr, started)
+
+    def patch_topublish(self):
+        self.patch_target('_relations')
+        relation = mock.MagicMock()
+        to_publish = mock.PropertyMock()
+        type(relation).to_publish = to_publish
+        self._relations.__iter__.return_value = [relation]
+        return relation.to_publish
+
+    def test_registered_hooks(self):
+        # test that the hooks actually registered the relation expressions that
+        # are meaningful for this interface: this is to handle regressions.
+        # The keys are the function names that the hook attaches to.
+        hook_patterns = {
+            'changed': (
+                '{provides:neutron-plugin}-'
+                'relation-{joined,changed}', ),
+            'broken': (
+                '{provides:neutron-plugin}-'
+                'relation-{broken,departed}', ),
+        }
+        for k, v in _hook_args.items():
+            self.assertEqual(hook_patterns[k], v['args'])
+
+    def test_changed(self):
+        conversation = mock.MagicMock()
+        self.patch_target('conversation', conversation)
+        self.patch_target('set_state')
+        self.target.changed()
+        self.set_state.assert_has_calls([
+            mock.call('{relation_name}.connected'),
+        ])
+
+    def test_broken(self):
+        conversation = mock.MagicMock()
+        self.patch_target('conversation', conversation)
+        self.patch_target('remove_state')
+        self.target.broken()
+        self.remove_state.assert_has_calls([
+            mock.call('{relation_name}.connected'),
+        ])
+
+    def test_configure_plugin(self):
+        conversation = mock.MagicMock()
+        self.patch_target('conversation', conversation)
+        self.patch_target('set_remote')
+        self.target.configure_plugin('aPlugin',
+                                     {'aKey': 'aValue'},
+                                     )
+        conversation.set_remote.assert_called_once_with(
+            **{
+                'neutron-plugin': 'aPlugin',
+                'subordinate_configuration': json.dumps({'aKey': 'aValue'})},
+        )
+
+    def test_get_or_create_shared_secret(self):
+        self.patch_target('get_local')
+        self.get_local.return_value = None
+        self.patch_target('set_local')
+        self.patch_object(provides.uuid, 'uuid4')
+        self.uuid4.return_value = 'fake-uuid'
+        self.assertEquals(
+            self.target.get_or_create_shared_secret(), 'fake-uuid')
+        self.set_local.assert_called_once_with(
+            provides.METADATA_KEY, 'fake-uuid')
+
+    def test_publish_shared_secret(self):
+        conversation = mock.MagicMock()
+        self.patch_target('conversation', conversation)
+        self.patch_target('get_or_create_shared_secret')
+        self.get_or_create_shared_secret.return_value = 'fake-uuid'
+        self.target.publish_shared_secret()
+        conversation.set_remote.assert_called_once_with(
+            **{provides.METADATA_KEY: 'fake-uuid'})

unit_tests/test_requires.py

@@ -0,0 +1,129 @@
+# Copyright 2019 Canonical Ltd
+#
+# 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 mock
+
+import charms_openstack.test_utils as test_utils
+
+import requires
+
+
+_hook_args = {}
+
+
+def mock_hook(*args, **kwargs):
+
+    def inner(f):
+        # remember what we were passed.  Note that we can't actually determine
+        # the class we're attached to, as the decorator only gets the function.
+        _hook_args[f.__name__] = dict(args=args, kwargs=kwargs)
+        return f
+    return inner
+
+
+class TestNeutronPluginRequires(test_utils.PatchHelper):
+
+    @classmethod
+    def setUpClass(cls):
+        cls._patched_hook = mock.patch('charms.reactive.hook', mock_hook)
+        cls._patched_hook_started = cls._patched_hook.start()
+        # force requires to rerun the mock_hook decorator:
+        # try except is Python2/Python3 compatibility as Python3 has moved
+        # reload to importlib.
+        try:
+            reload(requires)
+        except NameError:
+            import importlib
+            importlib.reload(requires)
+
+    @classmethod
+    def tearDownClass(cls):
+        cls._patched_hook.stop()
+        cls._patched_hook_started = None
+        cls._patched_hook = None
+        # and fix any breakage we did to the module
+        try:
+            reload(requires)
+        except NameError:
+            import importlib
+            importlib.reload(requires)
+
+    def setUp(self):
+        self._patches = {}
+        self._patches_start = {}
+        conversation = mock.MagicMock()
+        self.target = requires.NeutronPluginRequires(
+            'some-relation', [conversation])
+
+    def tearDown(self):
+        self.target = None
+        for k, v in self._patches.items():
+            v.stop()
+            setattr(self, k, None)
+        self._patches = None
+        self._patches_start = None
+
+    def patch_target(self, attr, return_value=None):
+        mocked = mock.patch.object(self.target, attr)
+        self._patches[attr] = mocked
+        started = mocked.start()
+        started.return_value = return_value
+        self._patches_start[attr] = started
+        setattr(self, attr, started)
+
+    def patch_topublish(self):
+        self.patch_target('_relations')
+        relation = mock.MagicMock()
+        to_publish = mock.PropertyMock()
+        type(relation).to_publish = to_publish
+        self._relations.__iter__.return_value = [relation]
+        return relation.to_publish
+
+    def test_registered_hooks(self):
+        # test that the hooks actually registered the relation expressions that
+        # are meaningful for this interface: this is to handle regressions.
+        # The keys are the function names that the hook attaches to.
+        hook_patterns = {
+            'changed': (
+                '{requires:neutron-plugin}-'
+                'relation-{joined,changed}', ),
+            'broken': (
+                '{requires:neutron-plugin}-'
+                'relation-{broken,departed}', ),
+        }
+        for k, v in _hook_args.items():
+            self.assertEqual(hook_patterns[k], v['args'])
+
+    def test_changed(self):
+        conversation = mock.MagicMock()
+        self.patch_target('conversation', conversation)
+        self.patch_target('set_state')
+        self.target.changed()
+        self.set_state.assert_has_calls([
+            mock.call('{relation_name}.connected'),
+        ])
+
+    def test_broken(self):
+        conversation = mock.MagicMock()
+        self.patch_target('conversation', conversation)
+        self.patch_target('remove_state')
+        self.target.broken()
+        self.remove_state.assert_has_calls([
+            mock.call('{relation_name}.connected'),
+        ])
+
+    def test_host(self):
+        conversation = mock.MagicMock()
+        conversation.get_remote.return_value = 'someHost.fqdn'
+        self.patch_target('conversation', conversation)
+        self.assertEquals(self.target.host(), 'someHost.fqdn')