Backup via Api not possible?

Hey, i am trying to setup a cronjob which exports my blog data as json on a daily basis. However, this seems not to be doable with the api, at least nothing is listend at Ghost Content API Documentation.
How can i achive my goal? Or are there other backups solutions?

You should backup your files and database. There are many standardised ways of doing that depending on the OS and database that you’re using. A full VPS snapshot could also work if that’s the type of backup you need, in that case it should be doable via your VPS provider with little effort.

I run ghost on a ubuntu vps with docker. What is the best way to back it up? A full VPS Snapshot is not doable with my provider…