Re: [Qemu-devel] [PATCH RFC v3 for-2.9 08/11] rbd: Revert -blockdev and -drive parameter auth-supported

[Eric Blake]

On 03/27/2017 01:31 PM, Markus Armbruster wrote:

>>> -
>>> -##
>>> -# @RbdAuthMethod:
>>> -#
>>> -# An enumeration of rados auth_supported types
>>> -#
>>> -# Since: 2.9
>>> -##
>>> -{ 'struct': 'RbdAuthMethod',
>>> -  'data': { 'auth': 'RbdAuthSupport' } }
>>> -
>>
>> Removing the .json QMP support is fine. But I'm reluctant to give R-b
>> without knowing for sure that -drive usage won't regress.
> 
> auth-supported landed in master only on March 2nd.

auth-supported via -blockdev-add only landed on March 2nd.  But
auth-supported via -drive landed in commit 60390a2, Jan 2016; and is in
use by libvirt:

src/qemu/qemu_command.c:
":key=%s:auth_supported=cephx\\;none",

> 
> What libvirt usage exactly do you think this could break?
> 

Libvirt has been managing rbd drives using -drive since at least libvirt
commit 5745cd1, in Nov 2011, where even back then it was passing:
            virBufferEscape(opt, ":", ":key=%s:auth_supported=cephx none",

(back when it used space instead of ; to separate the list of supported
auth types).

As I've never personally used RBD (whether through qemu directly, or
through libvirt), I'm extremely wary of breaking -drive usage that
"works" (for some definition of "works"), even though I have no qualms
making the QMP interface extremely limited.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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