Actually I was able to make OAuth2 work with Keycloak. But when I do this even if the user is authenticated on my site, when they go to my Discourse instance he needs to click on “Log in” button to get access to the information on the forum.
That is why I was tring to make SSO work with Keycloak, doing so I espect that if the user is already authenticated on my site he was able to access my Discourse instance without need to log in or click on “log in” button on Discourse home.