Secrets stored by libvirt may have attributes associated with them, using
the secret element. The secret element has two
optional attributes, each with values 'yes' and
'no', and defaulting to 'no':
ephemeralprivate
The top-level secret element may contain the following
elements:
uuiddescriptionusagetype attribute specifies the usage category, currently
only volume is defined. Specific usage categories are
described below.
This secret is associated with a volume, and it is safe to delete the
secret after the volume is deleted. The <usage
type='volume'> element must contain a
single volume element that specifies the key of the volume
this secret is associated with.
<secret ephemeral='no' private='yes'>
<description>LUKS passphrase for the main hard drive of our mail server</description>
<usage type='volume'>
<volume>/var/lib/libvirt/images/mail.img</volume>
</usage>
</secret>