The _create_ephemeral() method is responsible for creating ephemeral
disks with image type "raw" and formatting them with mkfs. In the case
of [libvirt]images_type "qcow2", _create_ephemeral() will create
backing files.
Currently we are not using a consistent naming convention for choosing
the filesystem label for ephemeral disks. When we create a server for
example, we go through the disks and label them "ephemeral0",
"ephemeral1", "ephemeral2", etc.
When we hard reboot a server, there is a check to create missing
backing files and if so, a new backing file will be created but instead
of being labeled "ephemeralN" the code attempts to label them with the
name of the backing file itself for example "ephemeral_1_40d1d2c". This
will fail if the filesystem used for ephemeral disks has limitations on
the length of filesystem label names (VFAT, XFS, ...). For example:
mkfs.vfat: Label can be no longer than 11 characters
This adds a helper method for obtaining ephemeral disks filesystem
label names and uses it the same way in the few places fs_label is
specified.
Closes-Bug: #2061701
Change-Id: Id033a5760272e4fb06dee2342414b26aa16ffe24
melanie witt
82856f95c6