OpenNebula

Assuming you have a ceph datastore set up, you can create an image from cdrom in the ceph pool, with the following command:

oneimage create -d ceph_datastore --name my_cdrom --type cdrom --path /tmp/my_cdrom.iso

However, when you try to use this cdrom image with a guest the guest creation fails:

onevm create -n guest1 --cpu 1 --vcpu 1 --memory 512 --disk my_hdd,my_cdrom

The xml for the CDROM image references a nonexistent file associated with the VM, rather than a network rbd source.

Compare the rbd 'os' disk with the 'cdrom' disk here:

<disk type='network' device='disk'>
    <source protocol='rbd' name='one/one-16'/>
    <target dev='vda'/>
    <driver name='qemu' type='raw' cache='writethrough'/>
</disk>

<disk type='file' device='cdrom'>
    <source file='/var/lib/one//datastores/0/88/disk.1'/>
    <target dev='hda'/>
    <readonly/>
    <driver name='qemu' type='raw' cache='writethrough'/>
</disk>

I manually edited the cdrom section of this xml and used it to create a vm with 'libvirt create':

<disk type='network' device='cdrom'>
    <source protocol='rbd' name='one/one-23'/>
    <target dev='hda'/>
    <readonly/>
    <driver name='qemu' type='raw' cache='writethrough'/>
</disk>

and the guest can successfully see the cdrom image.