Chore: Fix error handling in postDashboard, remove UserDisplayDTO, fix live redis client initialization (#87206)

* clean up error handling in postDashboard and remove UserDisplayDTO

* replace GetUserUID with GetUID and GetNamespacedUID, enforce namespace constant type

* lint fix

* lint fix

* more lint fixes

pkg/services/authn/authnimpl/service.go

@@ -373,7 +373,7 @@ func (s *Service) resolveIdenity(ctx context.Context, orgID int64, namespaceID a
 			}}, nil
 	}
 
-	resolver, ok := s.idenityResolverClients[namespaceID.Namespace()]
+	resolver, ok := s.idenityResolverClients[namespaceID.Namespace().String()]
 	if !ok {
 		return nil, authn.ErrUnsupportedIdentity.Errorf("no resolver for : %s", namespaceID.Namespace())
 	}

pkg/services/authn/authnimpl/service_test.go

@@ -514,7 +514,7 @@ func TestService_ResolveIdentity(t *testing.T) {
 	t.Run("should resolve for valid namespace if client is registered", func(t *testing.T) {
 		svc := setupTests(t, func(svc *Service) {
 			svc.RegisterClient(&authntest.MockClient{
-				NamespaceFunc: func() string { return authn.NamespaceAPIKey },
+				NamespaceFunc: func() string { return authn.NamespaceAPIKey.String() },
 				ResolveIdentityFunc: func(ctx context.Context, orgID int64, namespaceID authn.NamespaceID) (*authn.Identity, error) {
 					return &authn.Identity{}, nil
 				},

pkg/services/authn/clients/api_key.go

@@ -135,7 +135,7 @@ func (s *APIKey) Priority() uint {
 }
 
 func (s *APIKey) Namespace() string {
-	return authn.NamespaceAPIKey
+	return authn.NamespaceAPIKey.String()
 }
 
 func (s *APIKey) ResolveIdentity(ctx context.Context, orgID int64, namespaceID authn.NamespaceID) (*authn.Identity, error) {

pkg/services/authn/identity.go

@@ -71,16 +71,27 @@ type Identity struct {
 	// IDToken is a signed token representing the identity that can be forwarded to plugins and external services.
 	// Will only be set when featuremgmt.FlagIdForwarding is enabled.
 	IDToken string
+	// UserUID is the unique identifier for the entity in the Grafana database.
+	UserUID string
 }
 
 func (i *Identity) GetID() NamespaceID {
 	return i.ID
 }
 
-func (i *Identity) GetNamespacedID() (namespace string, identifier string) {
+func (i *Identity) GetNamespacedID() (namespace identity.Namespace, identifier string) {
 	return i.ID.Namespace(), i.ID.ID()
 }
 
+func (i *Identity) GetUID() NamespaceID {
+	ns, uid := i.GetNamespacedUID()
+	return identity.NewNamespaceIDString(ns, uid)
+}
+
+func (i *Identity) GetNamespacedUID() (namespace identity.Namespace, identifier string) {
+	return i.ID.Namespace(), i.UserUID
+}
+
 func (i *Identity) GetAuthID() string {
 	return i.AuthID
 }