Hi,
if you want to connect with auth_oidc to a keycloak server, the TTRSS_AUTH_OIDC_URL needs to be set to the base of the realm: “TTRSS_AUTH_OIDC_URL=https://your.keycloak.server.tld/realms/YourRealm”. The plugin itself (resp. the middleware used by it) will then query the /.well-known/openid-configuration endpoint (= https://your.keycloak.server.tld/realms/YourRealm/.well-known/openid-configuration).
IMHO at least the info about the .well-known part should be added to the readme of the auth_oidc plugin.
Bye,
Alexander.