On Tue, Mar 05, 2013 at 11:58:55PM +0530, Edison Su wrote: > > > > -----Original Message----- > > From: Marcus Sorensen [mailto:shadow...@gmail.com] > > Sent: Monday, March 04, 2013 10:26 PM > > To: cloudstack-dev@incubator.apache.org > > Subject: Re: [DISCUSS] getting rid of KVM patchdisk > > > > I've been thinking about how to tackle this, written a little concept code, > > and > > it seems fairly straightforward to include our own little python daemon that > > speaks JSON via this local character device in the system vm. I'm assuming > > we'd start it up at the beginning of cloud-early-config. > > > > What I'm not certain of is how to get the 'cmdline' bits into the system > > before > > cloud-early-config needs them. Do we block in cloud-early-config, waiting on > > getting the cmdline file before continuing, and push it via StartCommand? > > We put a lot of logic into init scripts inside system vm, which is > unnecessary complicated the system vm programming: > 1. init script is not portable, if people want to use other Linux > distribution as system vm OS, then he has to write his own init > scripts. > 2. init script is not easy to hack, it has its own dialect(how to > log message, how to write dependence etc) > 3. init script is running in a limited environment(some system wide > services are not available), put the limitation on what you can do > in a init script. > > Maybe we need to start working on new system vm programming model > now? Better to just put a python daemon inside system vm, and > provide restful API through link local ip address(or private ip if > it's vmware), then mgt server or hypervisor agent code can just send > commands to the python daemon through http, instead of ssh. >
+1 to this approach. Agent services in puppet nodes are implemented this way too. It also makes testing the systemVM in isolation without the existence of cloudstack easier if it's an API. > In your case, the python daemon, needs to wait on the well-defined > serial port(e.g > /dev/virtio-ports/org.apache.cloudstack.guest.agent), get cmdline, > then programming system vm itself, and reboot. > > > > > > > On Mon, Mar 4, 2013 at 5:27 PM, Marcus Sorensen <shadow...@gmail.com> > > wrote: > > > I tested this with Rohit's systemvm from master. It works fine, > > > provided you install the qemu-guest-agent software and modify the > > > libvirt xml definition of the system vm to include something like: > > > > > > <channel type='unix'> > > > <source mode='bind' path='/var/lib/libvirt/qemu/v-2-VM.agent'/> > > > <target type='virtio' name='org.qemu.guest_agent.0'/> > > > <alias name='channel0'/> > > > <address type='virtio-serial' controller='0' bus='0' port='1'/> > > > </channel> > > > > > > Then on the host you can connect to the > > > /var/lib/libvirt/qemu/v-2-VM.agent unix socket and send QMP JSON to do > > > things like write files. We can't execute the various scripts through > > > it, but we also don't have to use qemu-ga; we could have our own thing > > > listening on the unix socket. > > > > > > > > > > > > On Mon, Mar 4, 2013 at 3:24 PM, Marcus Sorensen > > <shadow...@gmail.com> wrote: > > >> I think this just requires an updated system vm (the virtio-serial > > >> portion). I've played a bit with the old debian 2.6.32-5-686-bigmem > > >> one and can't get the device nodes to show up, even though the > > >> /boot/config shows that it has CONFIG_VIRTIO_CONSOLE=y. However, if I > > >> try this with a CentOS 6.3 VM, on a CentOS 6.3 or Ubuntu 12.04 KVM > > >> host it works. So I'm not sure what's being used for the ipv6 update, > > >> but we can probably make one that works. We'll need to install > > >> qemu-ga and start it within the systemvm as well. > > >> > > >> On Mon, Mar 4, 2013 at 12:41 PM, Edison Su <edison...@citrix.com> > > wrote: > > >>> > > >>> > > >>>> -----Original Message----- > > >>>> From: Marcus Sorensen [mailto:shadow...@gmail.com] > > >>>> Sent: Sunday, March 03, 2013 12:13 PM > > >>>> To: cloudstack-dev@incubator.apache.org > > >>>> Subject: [DISCUSS] getting rid of KVM patchdisk > > >>>> > > >>>> For those who don't know (this probably doesn't matter, but...), > > >>>> when KVM brings up a system VM, it creates a 'patchdisk' on primary > > >>>> storage. This patchdisk is used to pass along 1) the authorized_keys > > >>>> file > > and 2) a 'cmdline' > > >>>> file that describes to the systemvm startup services all of the > > >>>> various properties of the system vm. > > >>>> > > >>>> Example cmdline file: > > >>>> > > >>>> template=domP type=secstorage host=172.17.10.10 port=8250 > > >>>> name=s-1- VM > > >>>> zone=1 pod=1 guid=s-1-VM > > >>>> resource=com.cloud.storage.resource.NfsSecondaryStorageResource > > >>>> instance=SecStorage sslcopy=true role=templateProcessor mtu=1500 > > >>>> eth2ip=192.168.100.170 eth2mask=255.255.255.0 > > gateway=192.168.100.1 > > >>>> public.network.device=eth2 eth0ip=169.254.1.46 > > eth0mask=255.255.0.0 > > >>>> eth1ip=172.17.10.150 eth1mask=255.255.255.0 > > mgmtcidr=172.17.10.0/24 > > >>>> localgw=172.17.10.1 private.network.device=eth1 > > >>>> eth3ip=172.17.10.192 > > >>>> eth3mask=255.255.255.0 storageip=172.17.10.192 > > >>>> storagenetmask=255.255.255.0 storagegateway=172.17.10.1 > > >>>> internaldns1=8.8.4.4 dns1=8.8.8.8 > > >>>> > > >>>> This patch disk has been bugging me for awhile, as it creates a > > >>>> volume that isn't really tracked anywhere or known about in > > >>>> cloudstack's database. Up until recently these would just litter > > >>>> the KVM primary storages, but there's been some triage done to > > >>>> attempt to clean them up when the system vms go away. It's not > > >>>> perfect. It also can be inefficient for certain primary storage > > >>>> types, for example if you end up creating a bunch of 10MB luns on a > > SAN for these. > > >>>> > > >>>> So my question goes to those who have been working on the system > > vm. > > >>>> My first preference (aside from a full system vm redesign, perhaps > > >>>> something that is controlled via an API) would be to copy these up > > >>>> to the system vm via SCP or something. But the cloud services start > > >>>> so early on that this isn't possible. Next would be to inject them > > >>>> into the system vm's root disk before starting the server, but if > > >>>> we're allowing people to make their own system vms, can we count on > > >>>> the partitions being what we expect? Also I don't think this will > > >>>> work for RBD, which qemu directly connects to, with the host OS > > unaware of any disk. > > >>>> > > >>>> Options? > > >>> > > >>> Could you take a look at the status of this projects in KVM? > > >>> http://wiki.qemu.org/Features/QAPI/GuestAgent > > >>> https://fedoraproject.org/wiki/Features/VirtioSerial > > >>> > > >>> Basically, we need a way to talk to guest VM(sending parameters to > > KVM guest) after VM is booted up. Both VMware/Xenserver has its own way > > to send parameters to guest VM through PV driver, but there is no such thing > > for KVM few years ago. -- Prasanna.,
