# https://www.youtube.com/watch?v=WDQIv-Kd6hk&t=22s
https://serverfault.com/questions/696747/routing-from-docker-containers-using-a-different-physical-network-interface-and

# in container shell
ip route get 8.8.8.8
8.8.8.8 via 10.255.224.1 dev eth0  src 10.255.224.4

# in docker shell
ip -4 -br a s dev br-traefik-net1
br-traefik-net1  UP             10.255.224.1/20

ip route get 8.8.8.8
8.8.8.8 via 10.0.0.2 dev mv-enp7s0 src 10.0.0.61 uid 0
    cache

ip r
default via 192.168.2.1 dev vee-eth1 proto static
default via 10.0.0.2 dev mv-enp7s0 proto static
10.0.0.0/24 dev mv-enp7s0 proto kernel scope link src 10.0.0.61
10.255.224.0/20 dev br-traefik-net1 proto kernel scope link src 10.255.224.1
10.255.240.0/24 dev br-traefik-net2 proto kernel scope link src 10.255.240.1
172.16.224.0/24 dev br-4da896b4a65a proto kernel scope link src 172.16.224.1
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown
172.18.0.0/16 dev br-f5ab0a59124f proto kernel scope link src 172.18.0.1
192.168.2.0/24 dev vee-eth1 proto kernel scope link src 192.168.2.6

sysctl net.ipv4.ip_forward
net.ipv4.ip_forward = 1

# reply packets
ip route get 10.255.224.4
10.255.224.4 dev br-traefik-net1 src 10.255.224.1 uid 0
    cache

ip -4 -br a s dev br-traefik-net1
br-traefik-net1  UP             10.255.224.1/20

tcpdump -ni mv-enp7s0 icmp
tcpdump -ni vee-eth1 icmp

#list namespaces
lsns -t net

cat ~/snat.conf

# load config
nft -f ~/snat.conf

# list loaded configs
nft list ruleset

Change metric of default route to interface
-------------------------------------------
ip r
default via 192.168.2.1 dev vee-eth1 proto static
default via 10.0.0.2 dev mv-enp7s0 proto static
10.0.0.0/24 dev mv-enp7s0 proto kernel scope link src 10.0.0.61
10.255.224.0/20 dev br-traefik-net1 proto kernel scope link src 10.255.224.1
10.255.240.0/24 dev br-traefik-net2 proto kernel scope link src 10.255.240.1
172.16.224.0/24 dev br-2a6971a42c02 proto kernel scope link src 172.16.224.1
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown
172.18.0.0/16 dev br-aa39a4420c90 proto kernel scope link src 172.18.0.1
192.168.2.0/24 dev vee-eth1 proto kernel scope link src 192.168.2.6
# then delete i/f, e.g. vee-eth1
ip route del default via 192.168.2.1
# then add with metric
ip route add default via 192.168.2.1 metric 50
ip r
default via 10.0.0.2 dev mv-enp7s0 proto static
default via 192.168.2.1 dev vee-eth1 metric 50
10.0.0.0/24 dev mv-enp7s0 proto kernel scope link src 10.0.0.61
10.255.224.0/20 dev br-traefik-net1 proto kernel scope link src 10.255.224.1
10.255.240.0/24 dev br-traefik-net2 proto kernel scope link src 10.255.240.1
172.16.224.0/24 dev br-2a6971a42c02 proto kernel scope link src 172.16.224.1
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown
172.18.0.0/16 dev br-aa39a4420c90 proto kernel scope link src 172.18.0.1
192.168.2.0/24 dev vee-eth1 proto kernel scope link src 192.168.2.6