state/machine: new agent API

state/apiserver/common/interfaces.go

 // Copyright 2013 Canonical Ltd.
 // Licensed under the AGPLv3, see LICENCE file for details.
 
 package common
 
 // Tagger is implemented by any entity with a Tag method, which should
 // return the tag of the entity (for instance a machine might return
 // the tag "machine-1")
 type Tagger interface {
         Tag() string
 }
 
 // Authorizer represents a value that can be asked for authorization
 // information on its associated authenticated entity. It is
 // implemented by an API server to allow an API implementation to ask
 // questions about the client that is currently connected.
 type Authorizer interface {
         // IsLoggedIn returns whether the user is currently logged in and
         // authenticated.
         IsLoggedIn() bool
 
         // AuthMachineAgent returns whether the authenticated entity is a
         // machine agent.
         AuthMachineAgent() bool
 
         // AuthOwner returns whether the authenticated entity is the same
         // as the given entity.
-        AuthOwner(entity Tagger) bool
+        AuthOwner(tag string) bool
 
         // AuthEnvironManager returns whether the authenticated entity is
         // a machine running the environment manager job.
         AuthEnvironManager() bool
 }