Ghost Blog, Part Two

I'm trying to work out backups today for my Ghost Blog. Ghost has a nice backup system built in to the GUI, but I'd like to work out a script to automatically do it for me. I found Ghost's documentation for backups. It lists the command ghost backup will create a .zip file with all the site's data. Cool, so I just need to run that through a docker exec command and I should be peachy.
Steps performed on DOCKER-01

• cd /apps/Ghost
• docker exec -it ghost_ghost_1 sh
• ghost backup
  • You can't run commands as the 'root' user.
  • Switch to your regular user, or create a new user with regular account privileges and use this user to run 'ghost backup'.
• exit
• docker exec -it --user 1000 ghost_ghost_1 sh
• ghost backup
  • ? Ghost instance is not currently running. Would you like to start it?

Huh. That makes no sense. Ghost is running in the container just fine, so I'm not sure what's going on. Reading Ghost's documentation tells me they don't make a docker image so they don't support it and recommend talking to Docker. But looking through Docker's documentation for the image points to people running into similar struggles with the container image, and Docker just saying the image is fine and to talk to Ghost. Ugh. I'll have to come up with a script myself.