Okta - apokalipto/devise_saml_authenticatable GitHub Wiki
Thanks to @taylor01 for this setup.
Okta configuration
Here is a screenshot of a working Okta configuration for a local dev/test configuration:
attribute-map.yml
# "urn:mace:dir:attribute-def:uid": "user_name"
# "urn:mace:dir:attribute-def:email": "email"
"last_name": "last_name"
"first_name": "first_name"