Hi,
As far as I know keycloak supports both SAML and OpenID Connect. Depending on which you want to use, you can check our documentation at:
https://www.elastic.co/guide/en/elasticsearch/reference/7.5/saml-guide-authentication.html
and / or
https://www.elastic.co/guide/en/elasticsearch/reference/7.5/oidc-guide-authentication.html
There are some more discuss posts around this which can provide more details:
Thanks
Rashmi