Reproduces the ip address appending problem with nmstate.

ip-addr-append-reproducer.sh

read -r -d '' ETH1 <<EOF
interfaces: 
  - name: eth1
    type: ethernet
    state: up
    ipv4:
      address: 
      - ip: 192.0.2.1
        prefix-length: 24
      dhcp: false
      enabled: true
    ipv6:
      address: 
      - ip: 2001:db8:1::1
        prefix-length: 64
      dhcp: false
      enabled: true
      autoconf: false
EOF

read -r -d '' ETH1_CHANGED_IP <<EOF
interfaces: 
  - name: eth1
    type: ethernet
    state: up
    ipv4:
      address: 
      - ip: 192.0.2.2
        prefix-length: 24
      dhcp: false
      enabled: true
    ipv6:
      address: 
      - ip: 2001:db8:1::2
        prefix-length: 64
      dhcp: false
      enabled: true
      autoconf: false
EOF

setup_eth1() {
  sudo ip link add eth1 type veth peer eth1_p
  sudo ip link set eth1 up
  sudo ip link set eth1_p up
}

cleanup_eth1() {
  sudo ip link delete eth1
}

main() {
  sudo systemctl stop NetworkManager
  setup_eth1
  echo "$ETH1" | sudo ./rust/target/debug/nmstatectl apply -k -
  echo "sleeping 1 second ..."
  sleep 1
  echo "$ETH1_CHANGED_IP" | sudo ./rust/target/debug/nmstatectl apply -k -
  echo "sleeping 1 second ..."
  sleep 1
  ip a show eth1
  ./rust/target/debug/nmstatectl show eth1 -k
  cleanup_eth1
}

main

Pre-requisites:

• rust toolchain
• nmstate source code

git clone https://github.com/nmstate/nmstate.git
cd nmstate
cd rust; cargo build