Openstack Microstack : How to enable multidomain support for Horizon

I recently installed Microstack, Horizon dashboard is up. I wanted to test multi domain feature. I am not sure what config change is required for the same and in which file . I have looked at some places and they say, HORIZON_KEYSTONE_MULTIDOMAIN=‘TRUE’ will have to be added to /etc/horizon/local_settings.py file .In my installation , I see a few of local_settings file , some in /snap/microstack and some in /var/snap/microstack directories.

Can you please suggest or point me to something which can be of help with this.
Thank you.

As per this, they mention adding HORIZON_KEYSTONE_MULTIDOMAIN=‘TRUE’ to a local settings file.

Thus, I went ahead and created a new Python file under /var/snap/microstack/common/etc/horizon/local_settings.d, namely _10_enable_multidomain_support.py which only contains the aforementioned Horizon variable definition.

After restarting Horizon service via sudo snap restart microstack.horizon-uwsgi, I can see the domain field in the login screen and also in the dropdown menu (at the navbar).

Given the above, you can now create a new domain, project and user and grant that user a role on that project.

e.g.

microstack.openstack domain create test-domain
microstack.openstack project create --domain test-domain demo
microstack.openstack user create --domain test-domain --password-prompt demo
microstack.openstack role add --project demo --user demo admin

To be able to see the “Identity > Domains” submenu, you need to assign your user the admin role under a given domain, for example default, as per this.

So something like this
openstack role add --domain default --user ADMIN_USER_ID admin