route-override: Meta CNI plugin for overriding IP route

Overview

route-override IPAM works as meta CNI plugin to override IP route given by previous CNI plugins. It is useful in a case with network-attachment-definition.

Supported runtime

Currently route-override verified its feature with podman and crio(with Kubernetes).

Download

Binaries (for 386/amd64) are in Releases.

Install via daemonset

Installing using the provided daemonset will copy the route-override binary to the /opt/cni/bin on each machine in your Kubernetes cluster.

git clone https://github.com/redhat-nfvpe/cni-route-override.git && cd cni-route-override/
kubectl create -f deployments/daemonset-install.yaml

Example Configuration

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

ECMP route example

addroutes can now express ECMP intent directly by providing a gws array:

{
    "type": "route-override",
    "addroutes": [
    {
        "dst": "10.200.0.0/24",
        "gws": ["192.168.200.1", "192.168.200.2"]
    }]
}

The same structure can be used inside delroutes to flush previously installed ECMP entries without adding new knobs.

Configuration Reference

• type: (string, required): "routing-override"
• flushroutes: (bool, optional): true if you flush all routes.
• flushgateway: (bool, optional): true if you flush default route (gateway).
• delroutes: (object, optional): list of routes add to the container namespace. Each route is a dictionary with "dst", optional "gw", and optional "gws" (array) fields. Set gws to target ECMP routes without introducing a new command. If both gw and gws are omitted, the interface gateway value will be used.
• addroutes: (object, optional): list of routes add to the container namespace. Each route is a dictionary with "dst", optional "gw", and optional "gws" (array) fields. When gws is provided the plugin programs an ECMP route that fans out to every gateway listed. If gw and gws are omitted, the interface gateway value will be used.
• skipcheck: (bool, optional): true if you want to skip CNI's check command. Please set true if you will change routes after its launch

Process Sequence

route-override will manipulate the routes as following sequences:

1. flush routes if flushroutes is enabled.
2. flush gateway if flushgateway is enabled.
3. delete routes in delroutes if delroutes has route and the route is exists in routes.
4. add routes in addroutes if addroutes has route.

Supported Arguments

The following args conventions are supported:

• flushroutes: (bool, optional): true if you flush all routes (except interface routes and link-local).
• flushgateway: (bool, optional): true if you flush default route (gateway).
• delroutes: (object, optional): list of routes add to the container namespace. Each route is a dictionary with "dst", optional "gw", and optional "gws" (array) fields. Set gws to describe ECMP routes that should be removed without relying on a separate command.
• addroutes: (object, optional): list of routes add to the container namespace. Each route is a dictionary with "dst", optional "gw", and optional "gws" (array) fields. Providing gws makes addroutes capable of adding ECMP routes directly.