How to make GitLab backup

Hello. I have installed gitlab from source, however, when I run

sudo -u git -H bundle exec rake gitlab:backup:create RAILS_ENV=production

The following error occurs:

sudo: bundle: command not found

I know that GitLab was developed in Ruby, however, I don’t have Ruby installed in my CentOS machine. I have seen that Ruby was installed by GitLab at /opt/gitlab/embedded/bin

I have installed bundler gem, but the same error occured. I have seen that bundle command is in the same folder as Ruby, so I have replaced the command by:

sudo -u git -H ./bundle exec rake gitlab:backup:create RAILS_ENV=production

But this other error occurs:

Could not locate Gemfile or .bundle/ directory

Any help, please? Is there a more friendly way to do a backup of all data?

Jaime