Comment 6 for bug 1998417

I doubt you had not completed the preparations before you started the service.
FYI: https://docs.openstack.org/skyline-apiserver/latest/install/docker-install-ubuntu.html

Please verify you have been created skyline database, skyline user and grant permissions corectly, And verify you have been create keystone user, service and endpoint of skyline before you start the skyline.

Insides, you should add port in the configuration 'database_url' in skyline.yaml.