VyOS

set interfaces ethernet eth0 address 192.168.100.15/24
set interfaces ethernet eth1 address 172.17.100.15/24
set interfaces ethernet eth2 address 10.1.100.1/24
commit
set protocols static route 0.0.0.0/0 next-hop 192.168.100.1
set protocols static route 0.0.0.0/0 next-hop 172.17.100.1
commit
set service nat rule 1 source address 10.1.100.0/24
set service nat rule 1 outbound-interface eth0
set service nat rule 1 type masquerade
commit
set service nat rule 2 source address 10.1.100.0/24
set service nat rule 2 outbound-interface eth1
set service nat rule 2 type masquerade
commit
set load-balancing wan interface-health eth0 failure-count 3
set load-balancing wan interface-health eth0 nexthop 192.168.100.1
set load-balancing wan interface-health eth0 test 10 ping
set load-balancing wan interface-health eth0 test 10 target 172.16.0.1
commit
set load-balancing wan interface-health eth1 failure-count 3
set load-balancing wan interface-health eth1 nexthop 172.17.100.1
set load-balancing wan interface-health eth1 test 10 ping
set load-balancinf wan interface-health eth1 test 10 target 172.16.0.1
commit
set load-balancing wan rule 10 inbound-interface eth2
set load-balancing wan rule 10 interface eth0
set load-balancing wan rule 10 interface eth1
commit
save

ref:

https://dbiers.me/high-availability-ha-vyatta-vyos-vrrp-on-profitbricks/ https://slipsoad.wordpress.com/cisco-ios/vyos-os/dual-wan-load-balancing-on-vyatta-2/