Re: [libvirt-users] changeBegin() on python API
On 10/30/2015 07:02 AM, Michal Privoznik wrote:
On 29.10.2015 15:22, Ramon Medeiros wrote:
> Hi,
>
> is changeBegin() working on python? I was trying to use the following
> method:
>
> if = conn.interfaceLookupByName("name")
> if.undefine()
>
> I saw that changeBegin() does not commit changes, but i can't use it.
>
This python API boils down to virInterfaceChangeBegin() but as such it's
implemented just for netcf backend. So if you're on a distro where udev
is used instead, the API will return an error.
Otherwise, this should work:
if = conn.interfaceLookupByName("name")
if.changeBegin()
if.undefine()
/* test if the connectivity to the host was not lost */
if.changeCommit()
I haven't ever used the python bindings for the interface APIs, but if
changeBegin is implemented as a method of an interface, that is wrong -
virInterfaceChangeBegin() saves all the config for *all* interfaces on
the host, so it should instead be a method of the connection.
(To be more descriptive, virInterfaceChangeBegin() makes a copy of all
network interface config for all interfaces on the host. You can then
modify the network config as you wish (add/remove/modify interface
configs), then when you're sure the new config works, call
virInterfaceChangeCommit() to throw away the snapshotted copy of config.
If the host is rebooted without calling virInterfaceChangeCommit(), an
initscript (or whatever they call the equivalent in systemd) called
during boot will replace the new network config with whatever it was at
the time virInterfaceChangeBegin() was called. You can also force this
rollback prior to boot by calling virinterfaceChangeRollback() (note
that rollback only affects the config files, *not* the current working
state of the network)).