F.2. Configuring Routes and Default Routes

There are two ways a host has default routes set. If the interface is using DHCP and the DHCP server offers a gateway address, the system uses a default route for that gateway. Otherwise, you can set a default route on an interface with a static IP.
Although the Linux kernel supports multiple default gateways, it only uses the one with the lowest metric. If there are multiple DHCP interfaces, this can result in an unpredictable default gateway. In this case, it is recommended to set defroute=no for interfaces other than the one using the default route.
For example, we want a DHCP interface (nic3) to be the default route. Use the following YAML to disable the default route on another DHCP interface (nic2): 
# No default route on this DHCP interface
- type: interface
  name: nic2
  use_dhcp: true
  defroute: false
# Instead use this DHCP interface as the default route
- type: interface
  name: nic3
  use_dhcp: true

Note

The defroute parameter only applies to routes obtained through DHCP.
To set a static route on an interface with a static IP, specify a route to the subnet. For example, we set a route to the 10.1.2.0/24 subnet through the gateway at 172.17.0.1 on the Internal API network: 
    - type: vlan
      device: bond1
      vlan_id: {get_param: InternalApiNetworkVlanID}
      addresses:
      - ip_netmask: {get_param: InternalApiIpSubnet}
      routes:
      - ip_netmask: 10.1.2.0/24
        next_hop: 172.17.0.1