Generic Veth Chaining

The generic veth chaining plugin enables CNI chaining on top of any CNI plugin that is using a veth device model. The majority of CNI plugins use such a model.

Validate that the current CNI plugin is using veth

  1. Log into one of the worker nodes using SSH

  2. Run ip -d link to list all network devices on the node. You should be able spot network devices representing the pods running on that node.

  3. A network device might look something like this:

    103: lxcb3901b7f9c02@if102: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
        link/ether 3a:39:92:17:75:6f brd ff:ff:ff:ff:ff:ff link-netnsid 18 promiscuity 0
        veth addrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
    
  4. The veth keyword on line 3 indicates that the network device type is virtual ethernet.

If the CNI plugin you are chaining with is currently not using veth then the generic-veth plugin is not suitable. In that case, a full CNI chaining plugin is required which understands the device model of the underlying plugin. Writing such a plugin is trivial, contact us on Slack for more details.

Create a CNI configuration to define your chaining configuration

Create a chaining.yaml file based on the following template to specify the desired CNI chaining configuration:

apiVersion: v1
kind: ConfigMap
metadata:
  name: cni-configuration
  namespace: kube-system
data:
  cni-config: |-
    {
      "name": "generic-veth",
      "cniVersion": "0.3.1",
      "plugins": [
        {
          "type": "XXX",
          [...]
        },
        {
          "type": "cilium-cni"
        }
      ]
    }

Deploy the ConfigMap:

kubectl apply -f chaining.yaml

Deploy Cilium with the portmap plugin enabled

Download the Cilium release tarball and change to the kubernetes install directory:

curl -LO https://github.com/cilium/cilium/archive/v1.6.tar.gz
tar xzvf v1.6.tar.gz
cd cilium-1.6/install/kubernetes

Install Helm to prepare generating the deployment artifacts based on the Helm templates.

Generate the required YAML file and deploy it:

helm template cilium \
  --namespace=kube-system \
  --set global.cni.chainingMode=generic-veth \
  --set global.cni.customConf=true \
  --set global.cni.configMap=cni-configuration \
  --set global.tunnel=disabled \
  --set global.masquerade=false \
  > cilium.yaml
kubectl create -f cilium.yaml