Is it not possible to install Horizon using UCA/Yoga on Focal:
Step 4/12 : RUN apt-get update && apt-get -y install --no-install-recommends gettext locales openstack-dashboard python3-cloudkitty-dashboard python3-designate-dashboard python3-freezer-web-ui python3-heat-dashboard python3-ironic-ui python3-magnum-ui python3-manila-ui python3-mistral-dashboard python3-murano-dashboard python3-neutron-vpnaas-dashboard python3-octavia-dashboard python3-sahara-dashboard python3-senlin-dashboard python3-trove-dashboard python3-vitrage-dashboard python3-watcher-dashboard tzdata && apt-get clean && rm -rf /var/lib/apt/lists/*
Ign:1 http://mirror-int.iad.rax.opendev.org/ubuntu focal InRelease
Ign:2 http://mirror-int.iad.rax.opendev.org/ubuntu focal-updates InRelease
Ign:3 http://mirror-int.iad.rax.opendev.org/ubuntu focal-security InRelease
Ign:4 http://mirror-int.iad.rax.opendev.org/ubuntu-cloud-archive focal-updates/yoga InRelease
Get:5 http://mirror-int.iad.rax.opendev.org/ubuntu focal Release [4,651 B]
Get:6 http://mirror-int.iad.rax.opendev.org/ubuntu focal-updates Release [4,664 B]
Get:7 http://mirror-int.iad.rax.opendev.org/ubuntu focal-security Release [4,654 B]
Get:8 http://mirror-int.iad.rax.opendev.org/ubuntu-cloud-archive focal-updates/yoga Release [2,588 B]
Ign:9 http://mirror-int.iad.rax.opendev.org/ubuntu focal Release.gpg
Ign:10 http://mirror-int.iad.rax.opendev.org/ubuntu focal-updates Release.gpg
Ign:11 http://mirror-int.iad.rax.opendev.org/ubuntu focal-security Release.gpg
Ign:12 http://mirror-int.iad.rax.opendev.org/ubuntu-cloud-archive focal-updates/yoga Release.gpg
Get:13 http://mirror-int.iad.rax.opendev.org/ubuntu focal/universe amd64 Packages [15.7 MB]
Get:14 http://archive.ubuntu.com/ubuntu focal-backports InRelease [108 kB]
Get:15 http://archive.ubuntu.com/ubuntu focal-backports/universe amd64 Packages [26.0 kB]
Get:16 http://mirror-int.iad.rax.opendev.org/ubuntu focal/main amd64 Packages [1,645 kB]
Get:17 http://archive.ubuntu.com/ubuntu focal-backports/main amd64 Packages [51.2 kB]
Get:18 http://mirror-int.iad.rax.opendev.org/ubuntu focal-updates/main amd64 Packages [2,102 kB]
Get:19 http://mirror-int.iad.rax.opendev.org/ubuntu focal-updates/universe amd64 Packages [1,225 kB]
Get:20 http://mirror-int.iad.rax.opendev.org/ubuntu focal-security/universe amd64 Packages [891 kB]
Get:21 http://mirror-int.iad.rax.opendev.org/ubuntu focal-security/main amd64 Packages [1,670 kB]
Get:22 http://mirror-int.iad.rax.opendev.org/ubuntu-cloud-archive focal-updates/yoga/main amd64 Packages [238 kB]
Fetched 23.6 MB in 3s (8,367 kB/s)
Reading package lists...
Reading package lists...
Building dependency tree...
Reading state information...
locales is already the newest version (2.31-0ubuntu9.7).
tzdata is already the newest version (2022a-0ubuntu0.20.04).
tzdata set to manually installed.
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
openstack-dashboard : Depends: python3-django-horizon (= 4:22.1.0-0ubuntu2~cloud0) but it is not going to be installed
python3-designate-dashboard : Depends: python3-django-horizon (>= 4:18.6.0~) but it is not going to be installed
python3-freezer-web-ui : Depends: python3-django-horizon but it is not going to be installed
python3-heat-dashboard : Depends: python3-django-horizon (>= 4:18.6.0~) but it is not going to be installed
python3-ironic-ui : Depends: python3-django-horizon but it is not going to be installed
python3-magnum-ui : Depends: python3-django-horizon but it is not going to be installed
python3-manila-ui : Depends: python3-django-horizon (>= 4:18.6.0~) but it is not going to be installed
python3-murano-dashboard : Depends: python3-django-horizon (>= 4:18.6.0~) but it is not going to be installed
python3-neutron-vpnaas-dashboard : Depends: python3-django-horizon but it is not going to be installed
python3-octavia-dashboard : Depends: python3-django-horizon (>= 4:18.6.0~) but it is not going to be installed
python3-sahara-dashboard : Depends: python3-django-horizon (>= 4:18.6.0~) but it is not going to be installed
python3-senlin-dashboard : Depends: python3-django-horizon but it is not going to be installed
python3-trove-dashboard : Depends: python3-django-horizon (>= 4:18.6.0~) but it is not going to be installed
Depends: python3-django-openstack-auth (>= 2.0.0) but it is not going to be installed
python3-vitrage-dashboard : Depends: python3-django-horizon but it is not going to be installed
python3-watcher-dashboard : Depends: python3-django-horizon (>= 4:18.6.0~) but it is not going to be installed
[91mE: Unable to correct problems, you have held broken packages.