How to map users into groups
Currently we add users into groups manually in keycloak (e.g. to fairmeeting group, when a package has been ordered). This process is not scalable.
We need a UI for that.
Candidates
Circles in nextcloud
very intuitive management of groups
SCIM adapter for nextcloud is a client, not a server https://lab.libreho.st/libre.sh/scim/scimserviceprovider
API can list the circles I am a member of https://github.com/nextcloud/circles/blob/master/lib/Api/v1/Circles.php#L87
Keycloak UI - self service resource sharing
An OIDC client can be turned into a resource server. Depending on permissions, I could be offered a certain group, which I could select at the self service resource and share with others.
See https://www.keycloak.org/docs/latest/authorization_services/#_resource_server_enable_authorization
This is complex to set up and may not be very intuitive to use.