Skip validation when creating internal (ghost, service desk) users

app/models/user.rb

@@ -1068,11 +1068,13 @@ class User < ActiveRecord::Base
       User.find_by_email(s)
     end
 
-    scope.create(
+    user = scope.build(
       username: username,
       email: email,
       &creation_block
     )
+    user.save(validate: false)
+    user
   ensure
     Gitlab::ExclusiveLease.cancel(lease_key, uuid)
   end

changelogs/unreleased/dm-fix-ghost-user-validation.yml

+---
+title: Skip validation when creating internal (ghost, service desk) users
+merge_request:
+author:

spec/models/user_spec.rb

@@ -1556,6 +1556,16 @@ describe User, models: true do
         expect(ghost.email).to eq('ghost1@example.com')
       end
     end
+
+    context 'when a domain whitelist is in place' do
+      before do
+        stub_application_setting(domain_whitelist: ['gitlab.com'])
+      end
+
+      it 'creates a ghost user' do
+        expect(User.ghost).to be_persisted
+      end
+    end
   end
 
   describe '#update_two_factor_requirement' do