permissions - services - keycloak scopes

Resources, scopes, permissions and policies in keycloak (0)

I want to create a fairly simple role-based access control system using Keycloak's authorizaion system. The system Keycloak is replacing allows us to create a "user", who is a member of one or more "groups". In this legacy system, a user is given "permission" to access each of about 250 "capabilities" either through group membership (where groups are assigned permissions) or a direct grant of a permission to the user.

I would like to map the legacy system to keycloak authorizations.

It should be simple for me to map each "capability" in the existing system to a keycloak resource and a set of keycloak scopes. For example, a "viewAccount" capability would obviously map to an "account" resource and a "view" scope; and "viewTransaction" maps to a "transaction" resource... but is it best practice to create just one "view" scope, and use it across multiple resources (account, transaction, etc)? Or should I create a "viewAccount" scope, a "viewTransaction" scope, etc?

Similarly, I'm a little confused about permissions. For each practical combination of resource and scope, is it usual practice to create a permission? If there are multiple permissions matching a given resource/scope, what does Keycloak do? I'm guessing that the intention of Keycloak is to allow me to configure a matrix of permissions against resources and scopes, so for example I could have permission to access "accounts" and permission for "view" scope, so therefore I would have permission to view accounts?

I ask because the result of all this seems to be that my old "viewAccount" capability ends up creating an "Account" resource, with "View" scope, and a "viewAccount" permission, which seems to get me back where I was. Which is fine, if it's correct.

Finally, obviously I need a set of policies that determine if viewAccount should be applied. But am I right that this means I need a policy for each of the legacy groups that a user could belong to? For example, if I have a "helpdesk" role, then I need a "helpdesk membership" policy, which I could then add to the "viewAccount" permission. Is this correct?