On 04/10/2017 07:32 PM, ashish mittal wrote:
Hi,
I'm trying to figure out what changes are needed in the libvirt vxhs
patch to support passing TLS X509 arguments to qemu, similar to the
following -
Sample QEMU command line passing TLS credentials to the VxHS block
device (run in secure mode):
./qemu-io --object
tls-creds-x509,id=tls0,dir=/etc/pki/qemu/vxhs,endpoint=client -c 'read
-v 66000 2.5k' 'json:{"server.host": "127.0.0.1",
"server.port": "9999",
"vdisk-id": "/test.raw", "driver": "vxhs",
"tls-creds":"tls0"}'
I was hoping to find some NBD code related to this, but not able to
locate it. Any pointers will be appreciated.
Well you have a couple of things to deal with... There's the creation of
the TLS object and there's altering the parameters used for the qemu
command based on your needs/model.
First off you'll need to figure out where/how you're going to define
where the TLS creds exist. For that, I suspect you'll have code similar
to how chardevTLS support was added. Essentially some way to either use
an existing TLS environment or a way to allow someone to define a vxhs
specific environment (hint, see src/qemu/qemu_conf.c, src/qemu/qemu.conf
- I've made changes recently there too).
For the TLS object creation on the command line, see
qemuBuildTLSx509CommandLine to see how the code builds the
"tls-creds-x509,id=tls0,dir=/etc/pki/qemu/vxhs,endpoint=client" portion
of your command line.
I forget if hot plug was in your plan, but see qemuDomainGetTLSObjects,
qemuDomainAddTLSObjects, and qemuDomainDelTLSObjects for that.
The rest of the command line is going to be a bit tricky since using the
"newer" driver syntax for libvirt is "sparse". Traditionally libvirt
has
used "-drive file=[$uri:]$path,format=$driver,..." (use grep "\-drive
file" tests/*/*.args from a libvirt git directory - you can grep that
output for gluster or rbd to see the uri format).
IIUC the qemu changes correctly though, you cannot use that "file="
syntax, instead you'll need to format the command line similar to how
things were done for gluster to add multiple host support where the
syntax is "-drive 'file.driver=gluster,file.volume=..." (use grep
"\-drive file.driver" tests/*/*.args to see how this is done for gluster).
That code/support was added in a series starting at commit id '22ad4a7c'
and working your way forward through about 18 patches. Using a visual
tool like gitk helps a lot...
I think what will be easiest is to start at that commit and look "up"
for gluster specific changes. Be careful not to fully cut-n-paste
because there have been patches since that time to fix some issues with
the initial implementation. I point it out only as a way for you to see
which modules and where "similar" code exists.
You'll also note there is an nbd patch in that series of patches - not
sure how much that helps, but it perhaps gives you some amount of
guidelines. Although I don't believe nbd was added to the command line -
it was just a way of syntax generation/testing.
John
Thanks,
Ashish
On Wed, Feb 1, 2017 at 8:36 AM, John Ferlan <jferlan(a)redhat.com> wrote:
> [...]
> Pressed send too soon, sigh.
>
>
>>>>
>>>> #1. Based on Peter's v2 comments, we don't want to support the
>>>> older/legacy syntax for VxHS, so it's something that should be
removed -
>>>> although we should check for it being present and fail if found.
>>>>
>>>
>>> I am testing with changed code to return error if legacy syntax is
>>> found for VxHS. Also added a test case to check for failure on legacy
>>> syntax and it seems to pass (test #41 below).
>>>
>>> Then I added a pass test case to check conversion from new native
>>> syntax to XML (test #40 below). That test fails with error
>>> 'qemuParseCommandLineDisk:901 : internal error: missing file parameter
>>> in drive 'file.driver=vxhs,file.vdisk-id=eb90327c-8302-4725-9e1b...'
>>
>> The qemu_parse_command.c changes while nice to have weren't even updated
>> when multiple gluster servers were added (e.g. commit id '' or
'7b7da9e28')
>> Check the changes to add the new s
>>
>> IOW: This code knows how to parse something like:
>>
>> -drive
>>
'file=gluster+unix:///Volume2/Image?socket=/path/to/sock,format=raw,if=none,id=drive-virtio-disk1'
>>
>> but it's clueless for:
>>
>> -drive file.driver=gluster,file.volume=Volume3,file.path=/Image.qcow2,\
>> file.server.0.type=tcp,file.server.0.host=example.org,file.server.0.port=6000,\
>> file.server.1.type=tcp,file.server.1.host=example.org,file.server.1.port=24007,\
>> file.server.2.type=unix,file.server.2.socket=/path/to/sock,format=qcow2,\
>> if=none,id=drive-virtio-disk2 \
>> -device virtio-blk-pci,bus=pci.0,addr=0x5,drive=drive-virtio-disk2,\
>> id=virtio-disk2
>>
>> See
>>>
>>> Looks like none of the existing tests in qemuargv2xmltest test for the
>>> parsing of new syntax, and qemuParseCommandLineDisk() expects to find
>>> 'file=' for a drive or it errors out. If this is true, will it be
able
>>> to parse the new syntax? Some help here please!
>
> So I wouldn't expect the VxHS code to be able to do that unless you
> wanted to be adventurous. The good news is that this code is primarily
> for developers that need to take a qemu command line to generate the
> libvirt syntax. It has not really been kept up to date with all the most
> recent command line changes. I started to try over a year ago, but got
> very side tracked.
>
>>>
>>> Output from the newly added test cases (40 should pass and 41 checks
>>> for error) :
>>>
>>> 40) QEMU ARGV-2-XML disk-drive-network-vxhs
>>> ... Got unexpected warning from qemuParseCommandLineString:
>>> 2017-01-28 00:57:30.814+0000: 10391: info : libvirt version: 3.0.0
>>> 2017-01-28 00:57:30.814+0000: 10391: info : hostname: localhost.localdomain
>>> 2017-01-28 00:57:30.814+0000: 10391: error :
>>> qemuParseCommandLineDisk:901 : internal error: missing file parameter
>>> in drive
'file.driver=vxhs,file.vdisk-id=eb90327c-8302-4725-9e1b-4e85ed4dc251,file.server.host=192.168.0.1,file.server.port=9999,format=raw,if=none,id=drive-virtio-disk0,cache=none'
>>> libvirt: QEMU Driver error : internal error: missing file parameter in
>>> drive
'file.driver=vxhs,file.vdisk-id=eb90327c-8302-4725-9e1b-4e85ed4dc251,file.server.host=192.168.0.1,file.server.port=9999,format=raw,if=none,id=drive-virtio-disk0,cache=none'
>>> FAILED
>>>
>>> 41) QEMU ARGV-2-XML disk-drive-network-vxhs-fail
>>> ... Got expected error from qemuParseCommandLineString:
>>> libvirt: QEMU Driver error : internal error: VxHS protocol does not
>>> support URI syntax
>>> 'vxhs://192.168.0.1:9999/eb90327c-8302-4725-9e1b-4e85ed4dc251'
>>> OK
>>> 42) QEMU ARGV-2-XML disk-usb ... OK
>>>
>>>
>>>
>>>> #2. Is the desire to ever support more than 1 host? If not, then is the
>>>> "server" syntax you've borrowed from the Gluster code
necessary? Could
>>>> you just go with the single "host" like NBD and SSH. As it
relates to
>>>> the qemu command line - I'm not quite as clear. From the example I
see
>>>> in commit id '7b7da9e28', the gluster syntax would have:
>>>>
>>>
>>> Present understanding is to have only one host. You are right, the
>>> "server" part is not necessary. Will have to check with the qemu
>>> community on this change.
>>>
>>>>
+file.server.0.type=tcp,file.server.0.host=example.org,file.server.0.port=6000,\
>>>>
+file.server.1.type=tcp,file.server.1.host=example.org,file.server.1.port=24007,\
>>>>
+file.server.2.type=unix,file.server.2.socket=/path/to/sock,format=qcow2,\
>>>>
>>>> whereas, the VxHS syntax is:
>>>>
+file.server.host=192.168.0.1,file.server.port=9999,format=raw,if=none,\
>>>>
>>>> FWIW: I also note there is no ".type=tcp" in your output - so
perhaps
>>>> the "default" is tcp unless otherwise specified, but I'm
sure of the
>>>> qemu syntax requirements in this area. I assume that since there's
only
>>>> 1 server, the ".0, .1, .2" become unnecessary (something added
by commit
>>>> id 'f1bbc7df4' for multiple gluster hosts).
>>>>
>>>
>>> That's correct. TCP is the default.
>>>
>>>> I haven't closedly followed the qemu syntax discussion, but it would
it
>>>> would be possible to use:
>>>>
>>>> +file.host=192.168.0.1,file.port=9999
>>>>
>>>
>>> That is correct. Above syntax would also work for us. I will pose this
>>> suggestion to the qemu community and update with their response.
>>>
>
> It's not that important... I was looking for a simplification and
> generation of only what's required. You can continue using the server
> syntax - perhaps just leave a note/comment in the code indicating the
> decision point and move on.
>
> [...]
>
> John