Add new interface 'dashboard'

openstack-dashboard exposes the hostnames (and IP addresses) that can be
used by users to load Horizon. There are 3 possible sources, they are
juju units ingress-address, os-public-hostname and vip config options

Closes-Bug: #2030094
Change-Id: I5eb524c6258f72980ef43175f2bed21d7ca078be
(cherry picked from commit 484b7d8260)
(cherry picked from commit 83ffa9eb3a)

hooks/dashboard-relation-changed

@@ -0,0 +1 @@
+horizon_hooks.py

hooks/dashboard-relation-joined

@@ -0,0 +1 @@
+horizon_hooks.py

hooks/horizon_hooks.py

@@ -224,6 +224,7 @@ def config_changed():
         ha_relation_joined(relation_id=relid)
 
     websso_trusted_dashboard_changed()
+    dashboard_relation_changed()
 
 
 @hooks.hook('identity-service-relation-joined')
@@ -463,6 +464,25 @@ def websso_trusted_dashboard_changed():
         })
 
 
+@hooks.hook('dashboard-relation-joined',
+            'dashboard-relation-changed')
+def dashboard_relation_changed():
+    """
+    Provide dashboard information.
+    """
+    relations = relation_ids('dashboard')
+    if not relations:
+        return
+
+    relation_settings = {
+        'os-public-hostname': config('os-public-hostname'),
+        'vip': config('vip'),
+    }
+
+    for rel_id in relations:
+        relation_set(rel_id, relation_settings=relation_settings, app=True)
+
+
 def main():
     try:
         hooks.execute(sys.argv)

metadata.yaml

@@ -22,6 +22,8 @@ provides:
     scope: container
   websso-trusted-dashboard:
     interface: websso-trusted-dashboard
+  dashboard:
+    interface: dashboard
 requires:
   identity-service:
     interface: keystone

unit_tests/test_horizon_hooks.py

@@ -230,6 +230,7 @@ class TestHorizonHooks(CharmTestCase):
                 ],
                 'certificates': [],
                 'ha': [],
+                'dashboard': [],
             }[rname]
         self.relation_ids.side_effect = relation_ids_side_effect
 
@@ -457,3 +458,19 @@ class TestHorizonHooks(CharmTestCase):
         self.register_configs().write_all.assert_called_with()
         _service_reload.assert_called_with('apache2')
         self.enable_ssl.assert_called_with()
+
+    def test_dashboard_relation_changed(self):
+        self.relation_ids.return_value = None
+        hooks.dashboard_relation_changed()
+
+        self.test_config.set('os-public-hostname', 'mydashboard.local')
+        self.test_config.set('vip', '1.2.3.4')
+        self.relation_ids.return_value = ['dashboard:0']
+        hooks.dashboard_relation_changed()
+
+        self.relation_set.assert_called_with(
+            'dashboard:0',
+            relation_settings={'os-public-hostname': 'mydashboard.local',
+                               'vip': '1.2.3.4'},
+            app=True,
+        )