diff --git a/ansible/roles/horizon/templates/local_settings.j2 b/ansible/roles/horizon/templates/local_settings.j2
index 3b7f86aa27..136741b8cf 100644
--- a/ansible/roles/horizon/templates/local_settings.j2
+++ b/ansible/roles/horizon/templates/local_settings.j2
@@ -785,9 +785,16 @@ SECURITY_GROUP_RULES = {
 # the enabled panel configuration.
 # You should not add settings to this list for out of tree extensions.
 # See: https://wiki.openstack.org/wiki/Horizon/RESTAPI
-REST_API_REQUIRED_SETTINGS = ['OPENSTACK_HYPERVISOR_FEATURES',
-                              'LAUNCH_INSTANCE_DEFAULTS',
-                              'OPENSTACK_IMAGE_FORMATS']
+REST_API_REQUIRED_SETTINGS = [
+    'CREATE_IMAGE_DEFAULTS',
+    'DEFAULT_BOOT_SOURCE',
+    'ENFORCE_PASSWORD_CHECK',
+    'LAUNCH_INSTANCE_DEFAULTS',
+    'OPENSTACK_HYPERVISOR_FEATURES',
+    'OPENSTACK_IMAGE_FORMATS',
+    'OPENSTACK_KEYSTONE_BACKEND',
+    'OPENSTACK_KEYSTONE_DEFAULT_DOMAIN',
+]
 
 # Additional settings can be made available to the client side for
 # extensibility by specifying them in REST_API_ADDITIONAL_SETTINGS
diff --git a/releasenotes/notes/sync-horizon-rest-api-required-settings-099875e53248b62c.yaml b/releasenotes/notes/sync-horizon-rest-api-required-settings-099875e53248b62c.yaml
new file mode 100644
index 0000000000..519d61c8a3
--- /dev/null
+++ b/releasenotes/notes/sync-horizon-rest-api-required-settings-099875e53248b62c.yaml
@@ -0,0 +1,14 @@
+---
+upgrade:
+  - |
+    The  default value of ``REST_API_REQUIRED_SETTINGS`` was synchronized with
+    Horizon. You may want to review settings exposed by the `updated
+    configuration
+    <https://docs.openstack.org/horizon/latest/configuration/settings.html#rest-api-required-settings>`__.
+fixes:
+  - |
+    Updates the default value of ``REST_API_REQUIRED_SETTINGS`` in Horizon
+    ``local_settings``, which enables some features such as `selecting the
+    default boot source for instances
+    <https://docs.openstack.org/horizon/latest/configuration/settings.html#default-boot-source>`__.
+    `LP#1891024 <https://launchpad.net/bugs/1891024>`__