How to use OAuth to login in keycloak?

I have successfully to set up a client in keycloak and login via openid connect.

can a client use oauth to login ? I don’t see guide in the document.

currently I am working on gitlab https://gitlab.com/satorix/omniauth-oauth2-generic#gitlab-config-example
it require below parameters:

    site: 'https://keycloak.test.com', # The URL for your OAuth 2 server
    user_info_url: '/auth/realms/<my realms>/protocol/openid-connect/userinfo', # The endpoint on your OAuth 2 server that provides user info for the current user
    authorize_url: '/auth/realms/<my realms>', # The authorization endpoint for your OAuth server,
    token_url: '/auth/realms/<my realms>/protocol/openid-connect/token' # The token request endpoint for your OAuth server

how to find them in keycloak ?

See: How to configure claims request parameter to external OpenID Connect Identity Provider

thanks. I find the in the document.
but encounter lots of problem…
I can redirect to keycloak login page.
after login, the gitlab show :
You need to sign in or sign up before continuing.

I feel that the gitlab fail to retrieve user info the keycloak

sometimes the keycloak report : Missing parameters: client_id
but the client id is in the url
https://keycloak.test.com:8443/auth/realms/test/protocol/openid-connect/auth?client_id=gitlab_oauth&redirect_uri=https%3A%2F%2Fgitlab.test.com%2Fusers%2Fauth%2Foauth2_generic%2Fcallback&response_type=code&state=067da547077b8e0eff3af91ca3a33e5cc95da76815fad164