Add support for deploying Horizon with Skyline

We change a default value of `horizon_webroot` to reflect the usecase
where both Horizon and Skyline are deployed. When it is the case,
horizon webroot URL will be changed to `/horizon`.

Depends-On: https://review.opendev.org/c/openstack/openstack-ansible/+/859446
Change-Id: Ia38311a6fde88292c090cf6289bf5b6c6279c479

defaults/main.yml

@@ -426,7 +426,9 @@ horizon_custom_themes: {}
 # value is the theme_name from the vars above
 horizon_default_theme: "default"
 
-horizon_webroot: /
+# URI through which Horizon will be available.
+# If Skyline is not deployed defaults to `/`, `/horizon` otherwise.
+horizon_webroot: "{{ (groups['skyline_all'] | default([])) | ternary('/horizon', '/') }}"
 
 horizon_bind_address: "{{ openstack_service_bind_address | default('0.0.0.0') }}"
 

releasenotes/notes/horizon_webroot-ae22a11343c1fb1e.yaml

@@ -0,0 +1,11 @@
+---
+fixes:
+  - |
+    Change of ``horizon_webroot`` variable is now respected and will be
+    reflected in Apache configuration to serve static files and define
+    wsgi path accordingly.
+features:
+  - |
+    Horizon is now co-installabe with Skyline dashboard. In case both
+    Horizon and Skyline are deployed, Horizon will be served by
+    `/horizon` URI.