Implement WEBSSO redirect

This patch adds ability to configure horizon auto redirections when
WEBSSO is used.

Depends-On: https://review.opendev.org/c/openstack/openstack-ansible/+/785800
Change-Id: I2a1beddaed3a31d1c01d1310dc8b739c9c93d9dd
Closes-Bug: #1922687

defaults/main.yml

@@ -483,4 +483,8 @@ horizon_keystone_admin_roles:
 # Set the "credentials" authentication choice to show as default.
 # The list of authentication mechanisms which include keystone
 # federation protocols and identity provider/federation protocol
+#horizon_websso_keystone_url: "{{ horizon_keystone_endpoint }}"
 horizon_websso_initial_choice: "credentials"
+horizon_websso_default_redirect: False
+horizon_websso_default_redirect_region: "{{ horizon_websso_keystone_url | default(horizon_keystone_endpoint) }}"
+horizon_websso_default_redirect_logout: ""

releasenotes/notes/horizon_websso_redirect-662cbf01b431efb1.yaml

@@ -0,0 +1,9 @@
+---
+features:
+  - |
+    Implemented horizon WEBSSO auto redirects. Following new variables
+    were added to manage redirects configuration:
+
+      - horizon_websso_default_redirect
+      - horizon_websso_default_redirect_region
+      - horizon_websso_default_redirect_logout

templates/horizon_local_settings.py.j2

@@ -190,6 +190,15 @@ WEBSSO_INITIAL_CHOICE = "{{ horizon_websso_initial_choice }}"
 WEBSSO_KEYSTONE_URL = "{{ horizon_websso_keystone_url }}"
 {% endif %}
 
+{% if horizon_websso_default_redirect | bool %}
+WEBSSO_DEFAULT_REDIRECT = "{{ horizon_websso_default_redirect }}"
+WEBSSO_DEFAULT_REDIRECT_PROTOCOL = "{{ horizon_websso_initial_choice }}"
+WEBSSO_DEFAULT_REDIRECT_REGION = "{{ horizon_websso_default_redirect_region }}"
+{% if horizon_websso_default_redirect_logout | length > 0 %}
+WEBSSO_DEFAULT_REDIRECT_LOGOUT = "{{ horizon_websso_default_redirect_logout }}"
+{% endif %}
+{% endif %}
+
 # The list of authentication mechanisms which include keystone
 # federation protocols and identity provider/federation protocol
 # mapping keys (WEBSSO_IDP_MAPPING). Current supported protocol