Authn: external identity sync (#73461)

* Authn: Add interface for external identity sync

This interface is implemented by authnimpl.Service and just triggers PostAuthHooks and skipping last seen update by default

* Authn: Add SyncIdentity to fake and add a new mock

pkg/services/authn/authnimpl/service.go

@@ -50,6 +50,9 @@ var (
 // make sure service implements authn.Service interface
 var _ authn.Service = new(Service)
 
+// make sure service implements authn.IdentitySynchronizer interface
+var _ authn.IdentitySynchronizer = new(Service)
+
 func ProvideService(
 	cfg *setting.Cfg, tracer tracing.Tracer,
 	orgService org.Service, sessionService auth.UserTokenService,
@@ -65,7 +68,7 @@ func ProvideService(
 	socialService social.Service, cache *remotecache.RemoteCache,
 	ldapService service.LDAP, registerer prometheus.Registerer,
 	signingKeysService signingkeys.Service, oauthServer oauthserver.OAuth2Server,
-) authn.Service {
+) *Service {
 	s := &Service{
 		log:            log.New("authn.service"),
 		cfg:            cfg,
@@ -228,11 +231,9 @@ func (s *Service) authenticate(ctx context.Context, c authn.Client, r *authn.Req
 		return nil, err
 	}
 
-	for _, hook := range s.postAuthHooks.items {
-		if err := hook.v(ctx, identity, r); err != nil {
-			s.log.FromContext(ctx).Warn("Failed to run post auth hook", "client", c.Name(), "id", identity.ID, "error", err)
-			return nil, err
-		}
+	if err := s.runPostAuthHooks(ctx, identity, r); err != nil {
+		s.log.FromContext(ctx).Warn("Failed to run post auth hook", "client", c.Name(), "id", identity.ID, "error", err)
+		return nil, err
 	}
 
 	if identity.IsDisabled {
@@ -249,6 +250,15 @@ func (s *Service) authenticate(ctx context.Context, c authn.Client, r *authn.Req
 	return identity, nil
 }
 
+func (s *Service) runPostAuthHooks(ctx context.Context, identity *authn.Identity, r *authn.Request) error {
+	for _, hook := range s.postAuthHooks.items {
+		if err := hook.v(ctx, identity, r); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func (s *Service) RegisterPostAuthHook(hook authn.PostAuthHookFn, priority uint) {
 	s.postAuthHooks.insert(hook, priority)
 }
@@ -332,6 +342,13 @@ func (s *Service) RegisterClient(c authn.Client) {
 	}
 }
 
+func (s *Service) SyncIdentity(ctx context.Context, identity *authn.Identity) error {
+	r := &authn.Request{OrgID: identity.OrgID}
+	// hack to not update last seen on external syncs
+	r.SetMeta(authn.MetaKeyIsLogin, "true")
+	return s.runPostAuthHooks(ctx, identity, r)
+}
+
 func orgIDFromRequest(r *authn.Request) int64 {
 	if r.HTTPRequest == nil {
 		return 0