We should provide a configuration option for how long the device config backups should be retained.
May be we can use period format here: PnYnMnD , ex: 1 yr - P1Y
Any configs older than configured time should be deleted.
whenever we successfully update a config, just get all the configs where lastCreated < ( current time - period)
If it is the only config for that specific interface, don't delete.
if it is more than one and this config is not the latest config, delete