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Join Worker Nodes

This section describes how to join worker nodes to the Kubernetes cluster using kubeadm join.

At the end of this section: - all worker nodes will be part of the cluster - nodes will be in Ready state - Pod networking will work across nodes

Prerequisites

Before joining worker nodes, ensure that:

  • Kubernetes control plane is initialized
  • Calico CNI is installed and running
  • kubeadm join command is available
  • Worker nodes completed OS Preparation
  • Kubernetes packages are installed on worker nodes

Verify cluster status on the control plane:

kubectl get nodes

Expected output:

  • control plane node is Ready

Retrieve the join command

On the control plane node, retrieve (or regenerate) the join command:

sudo kubeadm token create --print-join-command

Example output:

kubeadm join 192.168.1.53:6443 \
--token abcdef.0123456789abcdef \
--discovery-token-ca-cert-hash sha256:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

⚠️ This command is unique and time-limited.

Join worker nodes

Execute on each worker node

Run the kubeadm join command on each worker node only:

sudo kubeadm join 192.168.1.53:6443 \
--token abcdef.0123456789abcdef \
--discovery-token-ca-cert-hash sha256:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

This command:

  • registers the node with the API server
  • installs required certificates
  • starts kubelet on the worker node

Verify node registration

On the control plane, verify node status:

kubectl get nodes

Expected output:

  • control plane node: Ready
  • worker nodes: Ready

Example:

NAME        STATUS   ROLES           AGE     VERSION
cp-1        Ready    control-plane   20m     v1.34.x
worker-1    Ready    <none>           2m     v1.34.x
worker-2    Ready    <none>           2m     v1.34.x

Verify Pod scheduling across nodes

Deploy a test Pod:

kubectl run nginx-test --image=nginx --restart=Never

Check where the Pod is scheduled:

kubectl get pod nginx-test -o wide

Expected:

  • Pod is Running
  • Pod is scheduled on a worker node
  • Pod has an IP from the Pod CIDR range

Cleanup test Pod

kubectl delete pod nginx-test

Common issues

Node stays in NotReady

Check CNI status:

kubectl get pods -n kube-system

Ensure:

  • calico-node is running on the worker node
  • no CrashLoopBackOff

Join token expired

Generate a new token:

sudo kubeadm token create --print-join-command

Result

At this stage:

  • all nodes are successfully joined
  • Pod networking works across nodes
  • the Kubernetes cluster is fully operational