Plan reviewed with Codex; tried on a udev host (AlmaLinux 10) and a
netcf one (AlmaLinux 8).
- Changes are one change of the host's configuration (libvirt's
interface change transaction): a bridge that does not start used to
be undefined, leaving its member without the addresses and start
mode the bridge took from it; now the whole change rolls back, the
member's own configuration too, and so does a commit libvirt refuses.
A rollback that fails too is reported with the failure, saying the
host's configuration may be changed.
Deleting a bridge, which defines its
members again on their own, is one change as well.
- A running interface is not deleted: the page hid Delete, but a post
deleted it. A bridge with addresses and several members is refused
(which member takes the addresses is the user's choice); the
confirmation says that its members are defined again.
- A bridge takes only a device in no bridge, bond or VLAN as the host
has them configured, at any depth (a bridge's bond's devices), not
the loopback, a libvirt network's bridge or a VM's tap; an ethernet
interface configures only such a device too.
- Whether the host can change interfaces: unsupported or refused by
its access rules is a no, bad XML a yes, anything else (the
connection, the login) is raised instead of taken for a yes. A page
whose host could not be read offers no actions.
- Reads: the list reads each interface's XML once from one listing
(listAllInterfaces: every state, not the active and the defined ones
apart); a page reads the running and the saved definition once each
(cached_property). netcf writes a link speed of -1 for a card that
has none (a virtio one) and then refuses its own XML: the saved one
is read instead, where virsh and the page failed. Name and MAC come
from libvirt's object, without a call. Each family says how it is
addressed (DHCP, autoconf, static or none) and every address, its
prefix where it has one; no
address is not "DHCP" any more. A bridge's members carry their link
state and speed; an unknown speed (0, -1, 4294967295) is none.
- The interface API lists from the same reader. get_details,
get_bridge, get_bridge_slave_ifaces and the per-family getters go.
With the netcf backend (RHEL/AlmaLinux 8), undefining a bridge also
removes its members' configuration: the device came back without any
after a reboot. Like virsh iface-unbridge, each member is now defined
again on its own after the bridge is undefined, with the bridge's start
mode and, when it is the only member, its addresses. A bond keeps its
mode and devices.
Checked on AlmaLinux 8 (libvirt 8.0, netcf): an ethernet and a bond
member get their ifcfg back, and the bond comes up with the address
after a reboot.
