Abstract

This post describes a simple networking implementation with Flannel.

Deploy the Flannel Networking Add On

Cluster Status before Flannel

At this point in our cluster deployment we should have 1 control plane node and at least two worker nodes that will not present themselves as ready due to the lack of a proper CNI plugin.

current node status

NAME    STATUS     ROLES           AGE   VERSION
thw00   NotReady   control-plane   22h   v1.33.4
thw01   NotReady   <none>          13m   v1.33.4
thw02   NotReady   <none>          2s    v1.33.4
thw03   NotReady   <none>          2s    v1.33.4

In this post, we’ll install that plugin and make sure it’s working.

Flannel for networking

There are quite a few Networking Add Ons for Kubernetes to choose from.

The author has direct experience with Calico, Cillium, and Flannel of which Flannel is the easiest to work with and explain.

Flannel Install Guide

There are at least two methods for installing Flannel.

Install Flannel with kubectl

For those in a rush, the simplest method[1] is to install via kubectl apply.

kubectl apply -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml

Install Flannel with Helm

Deploying with Helm[2] requires a few more steps, but also allows for much easier customization.

1. Create a namespace called kube-flannel.

   make a namespace

   kubectl create ns kube-flannel
   

2. Enable privileged containers in the new kube-flannel namespace.

   update the namespace properties

   kubectl label --overwrite ns kube-flannel pod-security.kubernetes.io/enforce=privileged
   

3. Add the Flannel Helm repository to your local repositories.

   add the repository to your local list

   helm repo add flannel https://flannel-io.github.io/flannel/
   

4. Install Flannel with Helm, adjusting values as required.

   finally install flannel

   helm install flannel --set podCidr="10.244.0.0/16" --namespace kube-flannel flannel/flannel
   

   If this runs as expected, you’ll see a result like the following.

   flannel deployed via helm

   NAME: flannel
   LAST DEPLOYED: Sun Sep  7 07:43:51 2025
   NAMESPACE: kube-flannel
   STATUS: deployed
   REVISION: 1
   TEST SUITE: None
   

We now have a cluster that’s ready to run workloads.

Cluster Status after Flannel

With Flannel installed we can check the status of our cluster and see the control plane and our worker nodes reporting ready.

NAME    STATUS   ROLES           AGE     VERSION
thw00   Ready    control-plane   6d20h   v1.33.4
thw01   Ready    <none>          6d20h   v1.33.4
thw02   Ready    <none>          6d20h   v1.33.4
thw03   Ready    <none>          6d20h   v1.33.4

The next thing we’ll look at is enabling dynamically provisioned storage.

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[1]

Install with kubectl.

[2]

Install with Helm.

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