Install multipath dependencies when use-multipath is True

This change ensures that the multipath dependencies are installed
on the compute node when the use-multipath config flag is enabled.

Change-Id: I39b017398b95f5901d9bc57ffa0c59ff59f3a359
Closes-Bug: #1806830

config.yaml

@@ -470,8 +470,8 @@ options:
     type: boolean
     default: False
     description: |
-      Use a multipath connection for iSCSI volumes. Enabling this feature
+      Use a multipath connection for iSCSI or FC volumes. Enabling this feature
-      causes libvirt to discover and login to available iscsi targets before
+      causes libvirt to login, discover and scan available targets before
       presenting the disk via device mapper (/dev/mapper/XX) to the VM instead
       of a single path (/dev/disk/by-path/XX). If changed after deployment,
       each VM will require a full stop/start for changes to take affect.

hooks/nova_compute_hooks.py

@@ -110,6 +110,7 @@ from nova_compute_utils import (
     resume_unit_helper,
     get_availability_zone,
     remove_old_packages,
+    MULTIPATH_PACKAGES,
 )
 
 from charmhelpers.contrib.network.ip import (
@@ -248,6 +249,7 @@ def config_changed():
         NovaNetworkAppArmorContext().setup_aa_profile()
 
     install_vaultlocker()
+    install_multipath()
 
     configure_local_ephemeral_storage()
 
@@ -260,6 +262,13 @@ def install_vaultlocker():
             apt_install('vaultlocker', fatal=True)
 
 
+def install_multipath():
+    if config('use-multipath'):
+        installed = len(filter_installed_packages(MULTIPATH_PACKAGES)) == 0
+        if not installed:
+            apt_install(MULTIPATH_PACKAGES, fatal=True)
+
+
 @hooks.hook('amqp-relation-joined')
 def amqp_joined(relation_id=None):
     relation_set(relation_id=relation_id,

hooks/nova_compute_utils.py

@@ -141,6 +141,11 @@ PURGE_PACKAGES = [
     'python-nova',
 ]
 
+MULTIPATH_PACKAGES = [
+    'multipath-tools',
+    'sysfsutils',
+]
+
 HELD_PACKAGES = [
     'python-memcache',
     'python-six',
@@ -424,6 +429,11 @@ def determine_packages():
 
     packages.extend(determine_packages_arch())
 
+    # LP#1806830 - ensure that multipath packages are installed when
+    # use-multipath option is enabled.
+    if config('use-multipath'):
+        packages.extend(MULTIPATH_PACKAGES)
+
     if cmp_release >= 'rocky':
         packages = [p for p in packages if not p.startswith('python-')]
         packages.extend(PY3_PACKAGES)

unit_tests/test_nova_compute_hooks.py

@@ -258,6 +258,23 @@ class NovaComputeRelationsTests(CharmTestCase):
                 context.exception.message,
                 'Invalid migration-auth-type')
 
+    @patch.object(hooks, 'compute_joined')
+    def test_config_changed_use_multipath_false(self,
+                                                compute_joined):
+        self.test_config.set('use-multipath', False)
+        hooks.config_changed()
+        self.assertEqual(self.filter_installed_packages.call_count, 0)
+
+    @patch.object(hooks, 'compute_joined')
+    def test_config_changed_use_multipath_true(self,
+                                               compute_joined):
+        self.test_config.set('use-multipath', True)
+        self.filter_installed_packages.return_value = []
+        hooks.config_changed()
+        self.assertEqual(self.filter_installed_packages.call_count, 1)
+        self.apt_install.assert_called_with(hooks.MULTIPATH_PACKAGES,
+                                            fatal=True)
+
     @patch('nova_compute_hooks.nrpe')
     @patch('nova_compute_hooks.services')
     @patch('charmhelpers.core.hookenv')

unit_tests/test_nova_compute_utils.py

@@ -223,6 +223,34 @@ class NovaComputeUtilsTests(CharmTestCase):
         result = utils.determine_packages()
         self.assertTrue('nova-api-metadata' in result)
 
+    @patch.object(utils, 'nova_metadata_requirement')
+    @patch.object(utils, 'neutron_plugin')
+    @patch.object(utils, 'network_manager')
+    def test_determine_packages_use_multipath(self, net_man,
+                                              n_plugin, en_meta):
+        self.os_release.return_value = 'ocata'
+        en_meta.return_value = (False, None)
+        net_man.return_value = 'bob'
+        self.test_config.set('use-multipath', True)
+        self.relation_ids.return_value = []
+        result = utils.determine_packages()
+        for pkg in utils.MULTIPATH_PACKAGES:
+            self.assertTrue(pkg in result)
+
+    @patch.object(utils, 'nova_metadata_requirement')
+    @patch.object(utils, 'neutron_plugin')
+    @patch.object(utils, 'network_manager')
+    def test_determine_packages_no_multipath(self, net_man,
+                                             n_plugin, en_meta):
+        self.os_release.return_value = 'ocata'
+        en_meta.return_value = (False, None)
+        net_man.return_value = 'bob'
+        self.test_config.set('use-multipath', False)
+        self.relation_ids.return_value = []
+        result = utils.determine_packages()
+        for pkg in utils.MULTIPATH_PACKAGES:
+            self.assertFalse(pkg in result)
+
     @patch.object(utils, 'os')
     @patch.object(utils, 'nova_metadata_requirement')
     @patch.object(utils, 'network_manager')