The persistence can follow the DB container:

https://github.com/leg100/docker-ebs-attach

You'll need three fleet units in total:

  - one to attach the EBS volume (wrapping the above container)
  - one to mount the device to a directory on the host
  - one to run the DB container, with a bind mount to the host directory

If the CoreOS host terminates, the cluster will reschedule the units to another host.