https://concourse-ci.org/generic-oauth.html
CONCOURSE_OAUTH_DISPLAY_NAME=oauth
CONCOURSE_OAUTH_CLIENT_ID=concourse
CONCOURSE_OAUTH_CLIENT_SECRET: <keycloak client secret>
CONCOURSE_OAUTH_AUTH_URL=https://keycloak.example.com/auth/realms/<realm name>/protocol/openid-connect/auth
CONCOURSE_OAUTH_TOKEN_URL=https://keycloak.example.com/auth/realms/<realm name>/protocol/openid-connect/token
CONCOURSE_OAUTH_USERINFO_URL=https://keycloak.example.com/auth/realms/<realm name>/protocol/openid-connect/userinfo