CNI

By default, no CNI plugin is installed when a self-managed cluster is provisioned. As a user, you need to install your own CNI (e.g. Calico with VXLAN) for the control plane of the cluster to become ready.

This document describes how to use Flannel as your CNI solution.

Modify the Cluster resources

Before deploying the cluster, change the KubeadmControlPlane value at spec.kubeadmConfigSpec.clusterConfiguration.controllerManager.extraArgs.allocate-node-cidrs to "true"

apiVersion: controlplane.cluster.x-k8s.io/v1beta1
kind: KubeadmControlPlane
spec:
  kubeadmConfigSpec:
    clusterConfiguration:
      controllerManager:
        extraArgs:
          allocate-node-cidrs: "true"

Modify Flannel Config

(NOTE): This is based off of the instruction at: deploying-flannel-manually

You need to make an adjustment to the default flannel configuration so that the CIDR inside your CAPG cluster matches the Flannel Network CIDR.

View your capi-cluster.yaml and make note of the Cluster Network CIDR Block. For example:

apiVersion: cluster.x-k8s.io/v1beta1
kind: Cluster
spec:
  clusterNetwork:
    pods:
      cidrBlocks:
      - 192.168.0.0/16

Download the file at https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml and modify the kube-flannel-cfg ConfigMap. Set the value at data.net-conf.json.Network value to match your Cluster Network CIDR Block.

wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

Edit kube-flannel.yml and change this section so that the Network section matches your Cluster CIDR

kind: ConfigMap
apiVersion: v1
metadata:
  name: kube-flannel-cfg
data:
  net-conf.json: |
    {
      "Network": "192.168.0.0/16",
      "Backend": {
        "Type": "vxlan"
      }
    }

Apply kube-flannel.yml

kubectl apply -f kube-flannel.yml