default_policy = one_factor means 'any authenticated user', which is
authentication and not authorisation. The swarm UI is operator-only and
agents are getting authelia accounts of their own, so a session alone
would be enough to open it the day that lands - the vhost's auth_request
would be a check nobody fails.
Adds an access_control rule for the UI's domain requiring
subject = group:operators, present only when the UI is enabled. The
group name is a constant beside the rule: it is also what an operator
types into 'swarmctl user add --group', and a configurable name is one
more way for the rule and the account to disagree silently.
d337fec565