[libvirt] [RFC] new preferences requirement

[Osier Yang]

于 2010年12月01日 18:26, Daniel P. Berrange 写道:
> On Wed, Dec 01, 2010 at 05:35:38PM +0800, Osier Yang wrote:
>> Hi, all
>>
>>     We have some new requirements of preferences, I listed
>> which of them I known, and think is useful as follows:
>>
>> 1) for the path of x509 certificate and keys of client
>>
>>     The path of x509 certificate and keys of client is hard
>> coded in remote driver. e.g.
>>
>>     /* Defaults for PKI directory. */
>>     # define LIBVIRT_PKI_DIR SYSCONFDIR "/pki"
>>     # define LIBVIRT_CACERT LIBVIRT_PKI_DIR "/CA/cacert.pem"
>>     # define LIBVIRT_CLIENTKEY LIBVIRT_PKI_DIR "/libvirt/private
>> /clientkey.pem"
>>     # define LIBVIRT_CLIENTCERT LIBVIRT_PKI_DIR "/libvirt/clientcert.pem"
>
> We can't assume one set of certs/keys is suitable for all
> URIs, so making this a preference setting doesn't help. There
> needs to be a parameter in the URI to specify a cert/key name
> to override the defaults on a per-connection basis
>

yeah, reasonable, I didn't consider all of the drivers, will fix
this problem with adding parameters for URI.

>> 2) for default default driver and subdriver for disk image
>>
>>     Another requirement of new preference is default driver and subdriver
>> for disk images, currently we use "phy" for "driver" in virsh, and
>> "raw" for "subdriver" in qemu driver by default if user doesn't specify
>> them, it causes bugs, though we could say to user "you should use
>> options --driver and --subdriver", but these two options are optional.
>>
>>     IMHO, the best solution for those bugs is to provide new preferences.
>
> virsh is broken here. It shouldn't be setting the driver if the
> user doesn't specify it. The libvirt hypervisor specific drivers
> know the correct defaults if omitted, so virsh shouldn't try to
> guess this (wrongly) itself.
>

will fix it.

>> 3) for default NIC and storage type
>>
>>     "Chris Phillips" raised up the requirement not long ago:
>>
>>     http://www.redhat.com/archives/libvirt-users/2010-November/msg00033.html
>
> This doesn't belong in libvirt. See my reply in that thread.
>
>> ====================
>>
>>     Should we add these new preferences(if they are really neccessary)
>> in qemu.conf? or create new config file, e.g. The approch Justin
>> raised up an approch before:
>> http://www.redhat.com/archives/libvir-list/2010-November/msg00651.html
>>
>>     Though for Justin's approch, IMHO we'd better also to provide a
>> default config file, e.g. "/etc/libvirt/client.conf".
>
> Library APIs like libvirt shouldn't really rely on preference files,
> because such a file would silently change behaviour in ways that
> applications using the API may not expect. ie the preference
> may work nicely for one app/user of libvirt, but not for another
> app. Environment variables would cause similar problems too. Anything
> that needs to be configured should be configurable via the APIs or
> XML.
>

good to known, thanks :-)

- Osier
> Regards,
> Daniel