[libvirt] [PATCH 2/2] add default migrate uri in definition file

[Daniel P. Berrange]

On Wed, Apr 16, 2014 at 04:19:05AM +0000, chen.fan.fnst at cn.fujitsu.com wrote:
> Hi Daniel,
> 
> On Tue, 2014-04-15 at 12:04 +0100, Daniel P. Berrange wrote: 
> > On Tue, Apr 15, 2014 at 06:31:09PM +0800, Chen Fan wrote:
> > > Current virsh migrate command require specfying migration URI with
> > > command option.
> > > 
> > > Here is current step.
> > > 1) If user specifies --migrateuri on virsh migrate command, then the command
> > >    transfers the data to specified host.
> > > 2) If --migrateuri is not specified, the command transfers the data to host
> > >    whose name is resolved by DNS or /etc/hosts.
> > > 
> > >    but we are able to use virsh migrate command more usefull.
> > >    User can specify a constant destination by definition file.
> > >    if user want to specify other temporary destination, command option
> > >    is good for it.


> > 
> > IMHO the idea of storing the 'migration_uri' parameter in a configuration
> > file is just plain wrong. This value is inherantly associated with the
> > host that you're migrating to. So if you set 'migration_uri' to one host
> > in the config, but then invoke virDomainMigrate with a virConnectPtr that
> > is associated with a different host, this just crashes and burns. 
> 
> how about add a optional 'migrate_uri'(or 'data_migrate_uri') in
> libvirtd.conf as secondary network interface?
> if so, when user add a new NIC in host A, then user can store this NIC
> address to 'migrate_uri' parameter in the configuration file, then when 
> doing migration from other host B to this host A, we can get the
> 'migrate_uri' address in host A and pass this uri back to host B as the
> new 'uri_out' value at domainMigratePrepare3Params(). then we don't need
> to change any existing APIs. and the new NIC used to transfer migrate
> data will be more useful.

The problem is that the migrate_uri is tied to a specific target host,
while the API can be told to migrate to any host. I just dont see how
it makes sense to store this URI in any configuration file.

Regards,
Daniel
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