Updates for OpenStack Newton

Aodh switched to using wsgi_script to generate the aodh-api binary;
this resulted in a few packaging changes, including one which
means the listen port for Aodh API is set via the systemd unit,
rather than the aodh.conf configuration file.

Add systemd override file handling for aodh-api, including a small
workaround which ensures that the systemd daemon loads the override
configuration file when it changes.

This charm should switch to using Apache + mod_wsgi next cycle, at
which point all of that can just be dropped.

Change-Id: I196bc52f8399183cf1aea9271f946a08af145044
Closes-Bug: 1629796

src/lib/charm/openstack/aodh.py

@@ -13,8 +13,10 @@
 # limitations under the License.
 
 import os
+import subprocess
 
 import charmhelpers.contrib.openstack.utils as ch_utils
+import charmhelpers.core.host as ch_host
 
 import charms_openstack.charm
 import charms_openstack.adapters
@@ -22,6 +24,9 @@ import charms_openstack.ip as os_ip
 
 AODH_DIR = '/etc/aodh'
 AODH_CONF = os.path.join(AODH_DIR, 'aodh.conf')
+AODH_API_SYSTEMD_CONF = (
+    '/etc/systemd/system/aodh-api.service.d/override.conf'
+)
 
 
 class AodhAdapters(charms_openstack.adapters.OpenStackAPIRelationAdapters):
@@ -56,9 +61,6 @@ class AodhCharm(charms_openstack.charm.HAOpenStackCharm):
     services = ['aodh-api', 'aodh-evaluator',
                 'aodh-notifier', 'aodh-listener']
 
-    # Standard interface adapters class to use.
-    adapters_class = charms_openstack.adapters.OpenStackRelationAdapters
-
     # Ports that need exposing.
     default_service = 'aodh-api'
     api_ports = {
@@ -76,6 +78,7 @@ class AodhCharm(charms_openstack.charm.HAOpenStackCharm):
     # file changes
     restart_map = {
         AODH_CONF: services,
+        AODH_API_SYSTEMD_CONF: 'aodh-api',
     }
 
     # Resource when in HA mode
@@ -166,3 +169,12 @@ def configure_ssl():
     """Use the singleton from the AodhCharm to run configure_ssl
     """
     AodhCharm.singleton.configure_ssl()
+
+
+# TODO: drop once charm switches to apache+mod_wsgi
+def reload_and_restart():
+    """Reload systemd and restart aodh-api when override file changes
+    """
+    if ch_host.init_is_systemd():
+        subprocess.check_call(['systemctl', 'daemon-reload'])
+        ch_host.service_restart('aodh-api')

src/reactive/aodh_handlers.py

@@ -100,3 +100,9 @@ def cluster_connected(hacluster):
 @reactive.hook('upgrade-charm')
 def upgrade_charm():
     aodh.install()
+
+
+# TODO: drop once charm switches to apache+mod_wsgi
+@reactive.when_file_changed(aodh.AODH_API_SYSTEMD_CONF)
+def systemd_override_changed():
+    aodh.reload_and_restart()

src/templates/override.conf

@@ -0,0 +1,2 @@
+[Service]
+Environment=PORT={{ options.service_listen_info.aodh_api.port }}