Bulk creating users with rails etc

I think you shouldn’t develop rails or ember on a standard install, but I regularly to imports in a production container. Since it’s just a rake task you don’t even need to restart the server for changes to take effect.

Since it’s not public it should be safe to revert too a backup of something goes wrong. That’s probably where I would do it.

You could backup the live site and restore it to the dev site, do the work and then backup/restore back to the live site.