Libvirt OS distribution support matrix
This page documents the libvirt versions present in the various distro versions that OpenStack Nova aims to be deployable with.
Libvirt min version change policy
At the start of each Nova development cycle this matrix will be consulted to determine if it is viable to drop support for any end-of-life or otherwise undesired distro versions. Based on this distro evaluation, it may be possible to increase the min required version of libvirt in Nova, and thus drop some compatibility code for older versions.
When a decision to update the minimum required libvirt version is made, there must be a warning issued for one cycle. This is achieved by editting nova/virt/libvirt/driver.py to set
NEXT_MIN_LIBVIRT_VESION = (X, Y, Z)
This causes a deprecation warning to be printed when Nova starts up warning the admin that the version of libvirt they are on will be dropped in the subsequent release.
After a version has been listed in NEXT_MIN_LIBVIRT_VERSION for one release cycle, the corresponding actual min required libvirt can be updated by setting
MIN_LIBVIRT_VESION = (X, Y, Z)
At this point of course, an even newer version might be set in NEXT_MIN_LIBVIRT_VERSION to repeat the process....
There is more background on the rationale used for picking minimum versions in the operators mailing list thread here:
QEMU min version change policy
After deciding the minimum libvirt version, the minimum QEMU version is determined by looking for the lowest QEMU version from all the distros that support the decided libvirt version
Nova release min version
|Nova version||Current min libvirt||Next min libvirt||Current min QEMU||Next min QEMU|
Distro minimum versions
This table provides information on a representative sample of OS distros and the version of libirt/qemu/libguestfs that they ship. This is *NOT* intended to be an exhaustive list of distros where OpenStack Nova can run - it is intended to run on any Linux distro which can satisfy the minimum required software versions. This table merely aims to help identify when min required versions can be reasonably updated without loosing support for important OS distros.
When NEXT_MIN_LIBVIRT_VERSION is updated, any distros which don't meet that version should be changed to have
When MIN_LIBVIRT_VERSION is updated, any distros which don't meet that version should be deleted from this table
|14.04 (Trusty LTS)||1.2.2||2.0.0||1.24.5|
|16.04 (Xenial LTS)||1.3.1||2.5.0||1.32.2|
NB: maintain alphabetical ordering of distros, followed by oldest released versions first
NB2: RHEL versions of QEMU refer to the qemu-kvm-rhev RPM, not the qemu-kvm RPM, since the former is what is intended for use with OpenStack