Swap a physical interface with a bridge (KVM prep, CentOS 8)

swap-interface.sh

#!/bin/sh
#
## Interface-to-bridge swapper
## @oogali
#
# I want to run KVM, but I don't want dnsmasq
#  Because I want my VMs to have direct access to the LAN broadcast domain
#   Therefore I need a bridge interface
#    But I don't have one already, so I must create one
#     But I don't want to reboot nor do I want to create text files by hand
#      So this incantation of commands will give me what I want on CentOS 8 (and probably 7 too, but untested)
#

PHYS_IF=eno1
BRIDGE_IF=br-lan
LAN_IP=192.168.1.5/24
LAN_GW=192.168.1.1

virsh net-destroy default && \
  virsh net-autostart --network default --disable

cp /etc/sysconfig/network-scripts/ifcfg-${PHYS_IF} ~/ifcfg-${PHYS_IF}.bak

nmcli connection add type bridge ifname ${BRIDGE_IF} autoconnect yes save yes con-name ${BRIDGE_IF} bridge.stp no && \
  nmcli connection modify br-lan ipv4.method manual ipv4.addresses ${LAN_IP} ipv4.gateway ${LAN_GW} && \
  nmcli connection delete ${PHYS_IF} && \
  nmcli connection add type bridge-slave autoconnect yes con-name ${PHYS_IF} ifname ${PHYS_IF} master ${BRIDGE_IF} && \
  nmcli connection up ${BRIDGE_IF} && \
  nmcli connection up ${PHYS_IF}

diff -U1 ~/ifcfg-${PHYS_IF}.bak /etc/sysconfig/network-scripts/ifcfg-${PHYS_IF}