First, thanks to the OpenProject Team!  You a doing a great work! 
I use OpenProject's OpenID Connect plugin to autorize on a keycloak server. I would like to remove the step to press the SSO-Button on OpenProject's login screen.  So, if user has a valid ticket, he should be directed in OpenProject without login screen. 

Configuration is:

default:
 openid_connect keycloak:
_     sso: true_
_     host: "auth.beispiel.org"_
_     identifier: "OpenProjectBeispiel"_
_     secret: "secret"_
_     icon: "openid_connect/auth_provider-google.png"_
display_ame: "Beispiel  Authorisation"
     authorization_endpoint: "https://auth.beispiel.org/auth/realms/master/protocol/openid-connect/auth"
     token_endpoint: 'https://auth.beispiel.org/auth/realms/master/protocol/openid-connect/token'
     userinfo_endpoint: 'https://auth.beispiel.org/auth/realms/master/protocol/openid-connect/userinfo'
     end_session_endpoint: 'https://auth.beispieln.org/auth/realms/master/protocol/openid-connect/logout'
     check_session_iframe: 'https://auth.beispiel.org/auth/realms/master/protocol/openid-connect/login-status-iframe.html'
     issuer: 'https://openproject.beispiel.de/login'
     discovery: false

I forgot: "prompt: login" doesn't work. This para directs a user to keyloak login even with a valid ticket.

Found it!

Added these lines:

disable_password_login: true
 omniauth_direct_login_provider: keycloak