[keycloak-user] Unique Integer identifier in the Userinfo endpoint // automatically set up attributes?

[Rémy Grünblatt]

Hello,

for a specific application I need to provide a unique integer id in the
information returned by the userinfo endpoint (openid connect). Using
keycloak and mappers, I can return user attributes containing integers,
but I failed to find how to automatically create those attributes in a
way that would ensure each user would have an unique id (for example,
first user would get 1, second would get 2, and so on).

Is there a way to get such an unique integer id? (with either a mapper,
or by automatically setting up some attributes at the account creation?

Thanks,

Rémy