From 925b2caca73500310df02ded25051570a0d2e42e Mon Sep 17 00:00:00 2001
From: Frode Nordahl <frode.nordahl@canonical.com>
Date: Wed, 25 Sep 2019 17:12:26 +0200
Subject: [PATCH] Support plugin-subordinate request for db_migration

Change-Id: Iaefcb81fff5ed8a9441c93ac4c8bac3fa12eef15
---
 hooks/neutron_api_hooks.py           | 39 +++++++++++++++++++++-------
 unit_tests/test_neutron_api_hooks.py | 34 +++++++++++++++++++++---
 2 files changed, 60 insertions(+), 13 deletions(-)

diff --git a/hooks/neutron_api_hooks.py b/hooks/neutron_api_hooks.py
index ee54c7dd..0de4bc08 100755
--- a/hooks/neutron_api_hooks.py
+++ b/hooks/neutron_api_hooks.py
@@ -23,21 +23,24 @@ from subprocess import (
 )
 
 from charmhelpers.core.hookenv import (
+    DEBUG,
+    ERROR,
     Hooks,
     UnregisteredHookError,
     config,
+    is_leader,
+    leader_get,
+    leader_set,
     local_unit,
     log,
-    DEBUG,
-    ERROR,
+    open_port,
+    related_units,
     relation_get,
+    relation_id,
     relation_ids,
     relation_set,
     status_set,
-    open_port,
     unit_get,
-    related_units,
-    is_leader,
 )
 
 from charmhelpers.core.host import (
@@ -607,12 +610,28 @@ def ha_changed():
             'neutron-plugin-api-subordinate-relation-changed')
 @restart_on_change(restart_map(), stopstart=True)
 def neutron_plugin_api_subordinate_relation_joined(relid=None):
-    '''
-    -changed handles relation data set by a subordinate.
-    '''
-    relation_data = {'neutron-api-ready': 'no'}
+    relation_data = {}
+    if is_db_initialised():
+        db_migration_key = 'migrate-database-nonce'
+        if not relid:
+            relid = relation_id()
+        leader_key = '{}-{}'.format(db_migration_key, relid)
+        for unit in related_units(relid):
+            nonce = relation_get(db_migration_key, rid=relid, unit=unit)
+            if nonce:
+                if is_leader() and leader_get(leader_key) != nonce:
+                    migrate_neutron_database(upgrade=True)
+                    # track nonce in leader storage to avoid superfluous
+                    # migrations
+                    leader_set({leader_key: nonce})
+                # set nonce back on relation to signal completion to other end
+                # we do this regardless of leadership status so that
+                # subordinates connected to non-leader units can proceed.
+                relation_data[db_migration_key] = nonce
+
+    relation_data['neutron-api-ready'] = 'no'
     if is_api_ready(CONFIGS):
-        relation_data['neutron-api-ready'] = "yes"
+        relation_data['neutron-api-ready'] = 'yes'
     if not manage_plugin():
         neutron_cc_ctxt = NeutronCCContext()()
         plugin_instance = NeutronApiSDNContext()
diff --git a/unit_tests/test_neutron_api_hooks.py b/unit_tests/test_neutron_api_hooks.py
index f1edca58..d941dacb 100644
--- a/unit_tests/test_neutron_api_hooks.py
+++ b/unit_tests/test_neutron_api_hooks.py
@@ -950,15 +950,43 @@ class NeutronAPIHooksTests(CharmTestCase):
             **{'neutron-api-ready': 'no'}, relation_id=None)
         self.CONFIGS.write_all.assert_called_once_with()
         self.relation_set.reset_mock()
+        self.CONFIGS.reset_mock()
         _manage_plugin.return_value = False
         ncc_instance = _NeutronCCContext.return_value
         ncc_instance.return_value = {'core_plugin': 'aPlugin'}
         napisdn_instance = _NeutronApiSDNContext.return_value
         napisdn_instance.is_allowed.return_value = True
         self._call_hook('neutron-plugin-api-subordinate-relation-changed')
-        hooks.neutron_plugin_api_subordinate_relation_joined()
-        self.relation_set.assert_called_with(
+        self.relation_set.assert_called_once_with(
             **{'neutron-api-ready': 'no',
                'neutron_config_data': json.dumps({'core_plugin': 'aPlugin'})},
             relation_id=None)
-        self.CONFIGS.write_all.assert_called_with()
+        self.CONFIGS.write_all.assert_called_once_with()
+
+    @patch.object(hooks, 'manage_plugin')
+    @patch.object(hooks, 'is_api_ready')
+    @patch.object(hooks, 'leader_set')
+    @patch.object(hooks, 'migrate_neutron_database')
+    @patch.object(hooks, 'leader_get')
+    @patch.object(hooks, 'relation_id')
+    @patch.object(hooks, 'is_db_initialised')
+    def test_neutron_plugin_api_subordinate_relation_db_migration(
+            self, _is_db_initialised, _relation_id, _leader_get,
+            _migrate_neutron_database, _leader_set, _is_api_ready,
+            _manage_plugin):
+        _is_db_initialised.return_value = True
+        _relation_id.return_value = 'neutron-plugin-api-subordinate:42'
+        self.related_units.return_value = ['aUnit']
+        self.is_leader.return_value = True
+        self.relation_get.side_effect = None
+        self.relation_get.return_value = 'fake-uuid'
+        _leader_get.return_value = (
+            'migrate-database-nonce-neutron-plugin-api-subordinate:42')
+        _is_api_ready.return_value = True
+        _manage_plugin.return_value = True
+        self._call_hook('neutron-plugin-api-subordinate-relation-changed')
+        _migrate_neutron_database.assert_called_once_with(upgrade=True)
+        self.relation_set.assert_called_once_with(
+            relation_id='neutron-plugin-api-subordinate:42',
+            **{'migrate-database-nonce': 'fake-uuid',
+               'neutron-api-ready': 'yes'})