Red Hat OpenShift Container Platform

Configuring routes using the route-override plugin on a secondary network

The Route override CNI plugin JSON configuration object describes the configuration parameters for the route-override CNI plugin. The following table details these parameters:

Field Type Description

Field	Type	Description
`type`	`string`	The name of the CNI plugin to configure: `route-override`.
`flushroutes`	`boolean`	Optional: Set to `true` to flush any existing routes.
`flushgateway`	`boolean`	Optional: Set to `true` to flush the default route namely the gateway route.
`delroutes`	`object`	Optional: Specify the list of routes to delete from the container namespace.
`addroutes`	`object`	Optional: Specify the list of routes to add to the container namespace. Each route is a dictionary with `dst` and optional `gw` fields. If `gw` is omitted, the plugin uses the default gateway value.
`skipcheck`	`boolean`	Optional: Set this to `true` to skip the check command. By default, CNI plugins verify the network setup during the container lifecycle. When modifying routes dynamically with `route-override`, skipping this check ensures the final configuration reflects the updated routes.

type

string

The name of the CNI plugin to configure: route-override.

flushroutes

boolean

Optional: Set to true to flush any existing routes.

flushgateway

boolean

Optional: Set to true to flush the default route namely the gateway route.

delroutes

object

Optional: Specify the list of routes to delete from the container namespace.

addroutes

object

Optional: Specify the list of routes to add to the container namespace. Each route is a dictionary with dst and optional gw fields. If gw is omitted, the plugin uses the default gateway value.

skipcheck

boolean

Optional: Set this to true to skip the check command. By default, CNI plugins verify the network setup during the container lifecycle. When modifying routes dynamically with route-override, skipping this check ensures the final configuration reflects the updated routes.

Route-override plugin configuration example

The route-override CNI is a type of CNI that is designed to be used when chained with a parent CNI. The CNI type does not operate independently, but relies on the parent CNI to first create the network interface and assign IP addresses before the CNI type can modify the routing rules.

The following example configures a secondary network named mymacvlan. The parent CNI creates a network interface attached to eth1 and assigns an IP address in the 192.168.1.0/24 range by using host-local IPAM. The route-override CNI is then chained to the parent CNI and modifies the routing rules by flushing existing routes, deleting the route to 192.168.0.0/24, and adding a new route for 192.168.0.0/24 with a custom gateway.

{
    "cniVersion": "0.3.0",
    "name": "mymacvlan",
    "plugins": [
        {
            "type": "macvlan",
            "master": "eth1",
            "mode": "bridge",
            "ipam": {
                "type": "host-local",
                "subnet": "192.168.1.0/24"
            }
        },
        {
            "type": "route-override",
            "flushroutes": true,
            "delroutes": [
                {
                    "dst": "192.168.0.0/24"
                }
            ],
            "addroutes": [
                {
                    "dst": "192.168.0.0/24",
                    "gw": "10.1.254.254"
                }
            ]
        }
    ]
}

where:

"type": "macvlan": The parent CNI creates a network interface attached to eth1.
"type": "route-override": The chained route-override CNI modifies the routing rules.