cloudkitty: fix URL used for Prometheus collector

The Prometheus HTTP API is reachable under /api/v1. Without this fix,
CloudKitty receives 404 errors from Prometheus.

Change-Id: Ie872da5ccddbcb8028b8b57022e2427372ed474e
(cherry picked from commit b36c91b)

Author: priteau

ansible/roles/cloudkitty/defaults/main.yml

@@ -174,7 +174,7 @@ cloudkitty_collector_backend: "gnocchi"
 cloudkitty_monasca_interface: "internal"
 
 # Set prometheus collector URL.
-cloudkitty_prometheus_url: "{{ internal_protocol }}://{{ kolla_internal_fqdn | put_address_in_context('url') }}:{{ prometheus_port }}"
+cloudkitty_prometheus_url: "{{ internal_protocol }}://{{ kolla_internal_fqdn | put_address_in_context('url') }}:{{ prometheus_port }}/api/v1"
 
 # Path of the CA certificate to trust for HTTPS connections.
 # cloudkitty_prometheus_cafile: "{{ openstack_cacert }}"

releasenotes/notes/cloudkitty-prometheus-url-ee14bc486e810631.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes configuration of the Prometheus HTTP API URL when using the
+    Prometheus collector in CloudKitty.
+    `LP#1961615 <https://bugs.launchpad.net/kolla-ansible/+bug/1961615>`__