Handle user create race condition

app/models/authenticator/base.rb

@@ -137,7 +137,18 @@ def authorize(taskid, username, *args)
           end
 
           user.lastlogon = Time.now.utc
-          user.save!
+          if user.new_record?
+            User.with_lock do
+              user.save!
+            rescue ActiveRecord::RecordInvalid # Try update when catching create race condition.
+              userid, user = find_or_initialize_user(identity, username)
+              update_user_attributes(user, userid, identity)
+              user.miq_groups = matching_groups
+              user.save!
+            end
+          else
+            user.save!
+          end
 
           _log.info("Authorized User: [#{user.userid}]")
           task.userid = user.userid

spec/models/authenticator/httpd_spec.rb

@@ -272,6 +272,18 @@ def authenticate
                       'X-Remote-User-Email'     => 'Sally@example.com')
       end
 
+      context "with a race condition on create user" do
+        before do
+          authenticate
+        end
+
+        it "update the exiting user" do
+          allow(User).to receive(:lookup_by_userid).and_return(nil)
+          allow(User).to receive(:in_my_region).and_return(User.none, User.all)
+          expect { authenticate }.not_to(change { User.where(:userid => 'sally@example.com').count }.from(1))
+        end
+      end
+
       context "when user record with userid in upn format already exists" do
         let!(:sally_username) { FactoryBot.create(:user, :userid => 'sAlly') }
         let!(:sally_dn) { FactoryBot.create(:user, :userid => dn) }