On Mon, Jul 16, 2007 at 02:23:32PM -0500, Anthony Liguori wrote:
Daniel P. Berrange wrote:
On Mon, Jul 16, 2007 at 06:34:57PM +0100, Richard W.M. Jones wrote:
Daniel P. Berrange wrote:
On Mon, Jul 16, 2007 at 11:30:33AM -0500, Anthony Liguori wrote:
Richard W.M. Jones wrote:
Anthony Liguori wrote:
>For instance, let's say at a university they use an ldap directory to >authenticate users and they decide to implement a migration handler >that uses that for authentication. They may name this "uni://" and >it'll just work. How would they get at this in libvirt without >exposing URIs directly? > My latest proposal[1] has a transport parameter (a string) which covers this, in as much as it would allow you to construct URIs which are:
<transport>://<hostname>:<port>
SSH requires:
ssh://[user@]hostname[:port]
So that wouldn't work :-(
Sure it would - rich was just showing simplified syntax - the URI rules/spec allow for a username and we already use this syntax with a username in the remote driver URIs. eg
$ virsh --connect qemu+ssh://root@celery.virt.boston.redhat.com/system list --all
Anthony is right that my revised proposal limits the migration to just three parameters: transport, hostname and port.
https://www.redhat.com/archives/libvir-list/2007-July/msg00227.html
Perhaps instead we should replace hostname with a URI parameter, understood as either a simple hostname, IP address, a "hostname:port" string [IPv6?], or a full URI. However I feel inevitably this is going to cause hypervisor dependencies to come into libvirt code, which should be avoidable.
I think we can expose URIs without directly making the libvirt API hypervisor specific. Even though Anthony is talking with respect to QEMU/KVM there, the concepts is reasonably applicable to Xen too - there's no reason XenD could not be enhanced to support migration over a user-defined transport.
So, when thinking about URIs for migration we could consider that there are 2 classes of URI
- Pre-defined 'standard' URIs - TCP, TCP with SSL/TLS, and SSH being the most obvious - we can easily define clear & portable semantics for these URIs
- User-define 'custom' URIs - these are really site/deployment specific, rather than hypervisor specific. ie, if someone implemented a way to deal with foo://bar/, they could provide impls for both Xen & QEMU
How would a user define a custom URI?
A good question, to which I don't have any answer :-) Could just say that any unrecognised URI is passed down to the underlying driver without libvirt applying any interpretation of its own. Dan -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|