Add basic, running services only, NRPE support to the charm

Change-Id: Ib4b0dc8c47b77ec80845bd8987ebba11388604ab
Closes-Bug: #1871655

src/config.yaml

@@ -142,3 +142,17 @@ options:
       named by amp-ssh-key-name. Note that once the key is created it cannot be
       modified and the only way to do so is to delete it and have the charm
       create a new one.
+  nagios_context:
+    default: "juju"
+    type: string
+    description: |
+      A string that will be prepended to instance name to set the host name
+      in nagios. So for instance the hostname would be something like:
+          juju-myservice-0
+      If you're running multiple environments with the same services in them
+      this allows you to differentiate between them.
+  nagios_servicegroups:
+    default: "juju"
+    type: string
+    description: |
+      Comma separated list of nagios servicegroups for the graphite check

src/layer.yaml

@@ -8,6 +8,7 @@ includes:
   - interface:neutron-plugin
   - interface:ovsdb-subordinate
   - interface:ovsdb-cms
+  - interface:nrpe-external-master
 options:
   basic:
     use_venv: True

src/metadata.yaml

@@ -22,6 +22,10 @@ series:
   - eoan
   - focal
 subordinate: false
+provides:
+  nrpe-external-master:
+    interface: nrpe-external-master
+    scope: container
 requires:
   neutron-api:
     interface: neutron-load-balancer

src/reactive/octavia_handlers.py

@@ -24,6 +24,8 @@ import charms_openstack.ip as os_ip
 
 import charmhelpers.core as ch_core
 
+from charmhelpers.contrib.charmsupport import nrpe
+
 import charm.openstack.api_crud as api_crud
 import charm.openstack.octavia as octavia
 
@@ -214,3 +216,29 @@ def cluster_connected(hacluster):
     with charm.provide_charm_instance() as octavia_charm:
         octavia_charm.configure_ha_resources(hacluster)
         octavia_charm.assess_status()
+
+
+@reactive.when('charm.installed')
+@reactive.when('nrpe-external-master.available')
+@reactive.when_not('octavia.nrpe.configured')
+def update_nagios():
+    ch_core.hookenv.status_set('maintenance', 'configuring Nagios checks')
+    current_unit = nrpe.get_nagios_unit_name()
+    with charm.provide_charm_instance() as charm_instance:
+        services = charm_instance.full_service_list
+    nrpe_instance = nrpe.NRPE()
+    nrpe.add_init_service_checks(nrpe_instance, services, current_unit)
+    nrpe_instance.write()
+    reactive.set_state('octavia.nrpe.configured')
+    ch_core.hookenv.status_set('active', 'Nagios checks configured')
+
+
+@reactive.when_any('config.changed.nagios_context',
+                   'config.changed.nagios_servicegroups')
+def nagios_config_changed():
+    reactive.remove_state('octavia.nrpe.configured')
+
+
+@reactive.hook('upgrade-charm')
+def upgrade_charm():
+    reactive.remove_state('octavia.nrpe.configured')

unit_tests/test_octavia_handlers.py

@@ -62,10 +62,16 @@ class TestRegisteredHooks(test_utils.TestRegisteredHooks):
                     'identity-service.connected',),
                 'maybe_enable_ovn_driver': (
                     'ovsdb-subordinate.available',),
+                'update_nagios': (
+                    'charm.installed',
+                    'nrpe-external-master.available',),
             },
             'when_any': {
                 'sdn_joined': ('neutron-openvswitch.connected',
                                'ovsdb-subordinate.available'),
+                'nagios_config_changed': (
+                    'config.changed.nagios_context',
+                    'config.changed.nagios_servicegroups'),
             },
             'when_none': {
                 'sdn_broken': ('neutron-openvswitch.connected',
@@ -76,6 +82,10 @@ class TestRegisteredHooks(test_utils.TestRegisteredHooks):
                 'cluster_connected': ('ha.available',),
                 'generate_heartbeat_key': ('leadership.set.heartbeat-key',),
                 'disable_ovn_driver': ('ovsdb-subordinate.available',),
+                'update_nagios': ('octavia.nrpe.configured',),
+            },
+            'hook': {
+                'upgrade_charm': ('upgrade-charm',),
             },
         }
         # test that the hooks were registered via the
@@ -216,3 +226,22 @@ class TestOctaviaHandlers(test_utils.PatchHelper):
             'charm.octavia.enable-ovn-driver')
         self.octavia_charm.install.assert_called_once_with()
         self.octavia_charm.assess_status.assert_called_once_with()
+
+    def test_update_nagios(self):
+        self.patch_object(handlers.nrpe, 'get_nagios_unit_name',
+                          return_value=mock.sentinel.unit_name)
+        nrpe_instance = mock.MagicMock()
+        self.patch_object(handlers.nrpe, 'NRPE', return_value=nrpe_instance)
+        self.patch_object(handlers.nrpe, 'add_init_service_checks')
+        self.patch('charms.reactive.set_state')
+        handlers.update_nagios()
+        self.add_init_service_checks.assert_called_once_with(
+            nrpe_instance, self.octavia_charm.full_service_list,
+            mock.sentinel.unit_name)
+        nrpe_instance.write.assert_called_once()
+        self.set_state.assert_called_once_with('octavia.nrpe.configured')
+
+    def test_nagios_config_changed(self):
+        self.patch('charms.reactive.remove_state')
+        handlers.nagios_config_changed()
+        self.remove_state.assert_called_once_with('octavia.nrpe.configured')