Comment 0 for bug 1901732

As of Train release, Octavia supports creating amphora instances with a cinder volume as the root disk.
https://docs.openstack.org/releasenotes/octavia/train.html

Some extra values are require in the [cinder] section of the octavia.conf.

 volume_driver: set to create volume backed amphorae.
 volume_size: Size of root volume for Amphora Instance
 volume_type: Type of volume for Amphorae volume root disk
 volume_create_retry_interval: wait between retries
 volume_create_timeout: timeout for volume to be created
 volume_create_max_retries: retries to create volume

The octavia charm doesn't have a config-flags config option but even if it did, these settings are not in the [DEFAULT] section so we'd need new config options.