China OpenStack User Group

1. Look into libvirt
Osier Yang <jyang@redhat.com>

2. Status
● First release on Dec 19 2005
● 1.0.0 in two weeks. (Finally)
● 25 maitainers/commiters.
● 200 ~ 300 patches per release
● Less than 300 APIs

3. Why libvirt?
● Long term API/ABI/XML back-compact
● Portable between various HVs
● Hides complex interfaces of HV
● Hides HV's API changes
● Available on Linux, Solaris, Windows & OS-X
● Secure access (TLS, SASL, SSH, PolicyKit)
● Open, LGPLv2+ license

4. What libvirt manages
● Domain
● Virtual network
● Host network interface
● Node device
● Storage pool/volume
● Network filter
● Secret

5. Supported hypervisors
● QEMU/KVM
● XEN: XenD, XenStored, XM, libxenlight
● VMWare: ESX, GSX server, Workstation,
Player
● Linux container: LXC, OpenVZ
● Test, Remote
● UML, VirtualBox, Hyper-V, Parallels, etc

6. Virtual network
● Nat (dnsmasq/Radvd, iptables)
● Route
● Isolated
● Bridge (Open vSwitch, Macvtap)
● Host network interface passthrough (SR-IOV
VFs pool)

7. Host network interface
● Based on netcf -> augeas
● Enumerate
● Management(ethernets, bonds, bridges, vlan
interfaces)
● Transaction support – revert/commit config
changes
● Report status (libnl, ioctl, sysfs)

8. Network filter
● iptables
● ebtables
● Ip6tables
● E.g. allow-incoming-ipv4 no-ip-multicast

9. Storage
● pool, volume
● fs (dir, fs, netfs)
● scsi
● Iscsi
● Disk
● lvm
● mpath
● sheepdog, rbd

10. Node device
● Enumerate host devices
● Backends (udev, HAL)
● vHBA create/destroy

11. Secret
● Encrypt storage
● Can be used to encrypt a storage volume or
domain disk
● Only support qcow disks

12. Miscellaneous
● Hooks (Daemon, QEMU, LXC, Migration)
● Audit
● Security (Selinux/Apparmor, sVirt)
● Locking (libsanlock, POSIX fcntl)
● Zero-conf (Avahi)
● etc...

13. How to talk with QEMU
● Monitor (HMP, QMP)
● Guest agent monitor
● Serial/Parrell console
● Graphic console (vnc/spice)
● Network

14. Domain APIs (libvirt.h)
● Lifecyle (define/undefine, start/destroy,
suspend/resume), list, lookup.
● Save, restore, core dump, suspend, resume
● Migration
● Snapshot (Internal/External, Disk-only/
System checkpoint/VM state)
● Guest resource management (memory,
network, memory, cpu, NUMA tuning)

15. Domain APIs (libvirt.h)
● Host device passthrough
● Detach/reattach node devices
● Async events
● Node resource management (memory)
● APIs based on guest agent (E.g. S3/S4)
● Guest block/network I/O statistics
● ...more...

16. libvirt architecture
Node
client
libvirt-qemu
public API
Agent monitor
qemu-kvm
libvirtd
monitor
RPC
remote
$URI
uri = “qemu://$hostname/system" Guest
guest
agent

17. The stack
virsh
virsh bindings SNMP AMQP ......
public API
libvirtd
KVM XEN ESX LXC UML ......
Network Storage Iface nwfilter Secret Nodedev
cgroup netcf iptables ebtables tc libnl
lvm selinux sysfs udev HAL devmap
iscsiadm ioctl libnuma numad sanlock qemu-img

18. Stuffs around
● Language bindings (Python, Perl, Ruby, Jave,
OCaml, C#, PHP)
● Libvirt-snmp
● Libvirt-qpid
● Libvirt-cim
● libvirt-glib (libvirt-glib, libvirt-gconf, libvirt-
gobject)

19. Stuffs around
● Virt-manager
● virt-viewer
● python-virtinst
● Libosinfo
● Libvirt-designer
● Libvirt-sandbox
● Gnome Boxes

20. Stuffs around
● Virt-manager, virt-viewer
● python-virtinst
● Libosinfo
● Libvirt-designer
● Libvirt-sandbox
● Gnome Boxes
● Eucalyptus, openstack
● Plugins for collectd, munin, Nagios, Zenoss

21. libguestfs
● For accessing and modifying virtual machine
(VM) disk images
● View and edit files inside guests
● Scripting changes to VM
● Monitoring disk used/free statistics
● P2V, V2V
● Performing partial backups
● Cloning VMs, etc..

22. How libguestfs works
Appliance
client
qemu
guestfsd
libguestfs
Linux kernel
Device or
Disk image

23. virt-v2v
● Convert VMs on XEN/ESX to RH virt stack
● Support guests of RHEL, Fedora, Windows
● Based on libguestfs and libvirt

24. How virt-v2v works
● Shutdown guest on source host
● Use libvirt to get domain XML config
● Copy storage
● Convert storage and modify XML
● Use libvirt to define and start the domain on
dest host

25. The conversion - RHEL/FC
● Remove XEN/ESX specific stuffs (E.g.
xenpv kernel/drivers, VMWare tools)
● Install or update kernel, try best to let it
support virtio
● Update block and network drivers

26. Ongoing or TODO
● Snapshot improvements
● Storage driver improvements (glusterfs,
job, inotify)
● LXC driver improvements
● Persistent vHBA
● Migration with NPIV
● Associate storage with domain
● Improve device hotplug

27. Ongoing or TODO
● Lifecycle events for all objects
● Role based access control on all public APIs
● Isolate QEMU process with Linux Container
namespaces.
● APIs to expose host/hypervior's capabilities
● Etc...

28. http://libvirt.org
libvir­list@redhat.com
libvirt­user@redhat.com
#virt on OFTC