Re: [libvirt] [PATCH v3] Add support for Veritas HyperScale (VxHS) block device protocol

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&gt; 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