On Wed, 2015-06-17 at 10:35 +0100, Daniel P. Berrange wrote:
On Wed, Jun 17, 2015 at 09:43:23AM +0200, Cedric Bosdonnat wrote:
Hi Daniel,
On Thu, 2015-06-11 at 14:47 +0100, Daniel P. Berrange wrote:
On Wed, Jun 10, 2015 at 01:40:09PM +0200, Eren Yagdiran wrote:
Add the config gobject, functions to store and load the new configuration fragments and test. This will allow creating sandboxes with attached disk with a parameter formatted like file:hda=/source/file.qcow2,format=qcow2
+/** + * gvir_sandbox_config_add_disk_strv: + * @config: (transfer none): the sandbox config + * @disks: (transfer none)(array zero-terminated=1): the list of disks + * + * Parses @disks whose elements are in the format TYPE:TARGET=SOURCE,FORMAT=FORMAT + * creating #GVirSandboxConfigMount instances for each element. For + * example + * + * - file:hda=/var/lib/sandbox/demo/tmp.qcow2,format=qcow2 + */
One of the goal of the libvirt sandbox code is to insulate apps from needing to know hypervisor specific differences. The guest side disk device name is one such big difference. Many hypervisors, including kvm, will not even honour requested names - you just get whatever name the guest decides to give you. Essentially the only thing that libvirt guarantees is the disk ordering. ie if you configure two disks one with hda and one hdb, libvirt will ensure hda appears before hdb on the bus or controller.
So I don't think we should include the target device name in our configuration syntax here. We should just document that disks will be added to the guest in the same order that you supply them to virt-sandbox command line in. The actual device names will vary according to the hypevisor and guest os.
Right. But I think we then need to ask for the bus type then, so that we know whether we'll have ide, scsi or whatever. Then we could have the option like:
file:ide=/path/to/source,format=fmt
And of course document that the disks will be added in the same order.
Does it sound better for you?
Not really - that is still not achieving our goal that users should not need to details about the hypervisor used when configuring a sandbox.
The goal is that the CLI args to virt-sandbox should be unchanged, no matter what libvirt URI is provided. Now of course in the case of virtualized disks, what appears inside the sandbox could be differently named - ideally we'd find a way to insulate users from that aspect too.
In normal Linux there are various symlinks /dev/disk/by-{uuid,id,path} available which link back to /dev/[sda,vda,hda,etc]. These are created by udev, but we're not running that. I wonder if we could make use of that concept though - create /dev/disk/by-tag directory and then in the cli args we could allow a simple tag. eg
file:foobar=/path/to/source,format=fmt
and then populate a symlink /dev/disk/by-tag/foobar -> /dev/sda
I love this idea :) That would nicely solve the problem. -- Cedric