ansible-role-k3s/documentation/operations/extending-a-cluster.md

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Extending a cluster

This document describes the method for extending an cluster with new worker nodes.

Assumptions

It is assumed that you have already deployed a k3s cluster using this role, you have an appropriately configured inventory and playbook to create the cluster.

Below, our example inventory and playbook are as follows:

  • inventory: inventory.yml
  • playbook: cluster.yml

Currently your inventory.yml looks like this, it has two nodes defined, kube-0 (control node) and kube-1 (worker node).

---

k3s_cluster:
  hosts:
    kube-0:
      ansible_user: ansible
      ansible_host: 10.10.9.2
      ansible_python_interpreter: /usr/bin/python3
    kube-1:
      ansible_user: ansible
      ansible_host: 10.10.9.3
      ansible_python_interpreter: /usr/bin/python3

Method

We have our two nodes, one control, one worker. The goal is to extend this to add capacity by adding a new worker node, kube-2. To do this we will add the new node to our inventory.

---

k3s_cluster:
  hosts:
    kube-0:
      ansible_user: ansible
      ansible_host: 10.10.9.2
      ansible_python_interpreter: /usr/bin/python3
    kube-1:
      ansible_user: ansible
      ansible_host: 10.10.9.3
      ansible_python_interpreter: /usr/bin/python3
    kube-2:
      ansible_user: ansible
      ansible_host: 10.10.9.4
      ansible_python_interpreter: /usr/bin/python3

Once the new node has been added, you can re-run the automation to join it to the cluster. You should expect the majority of changes to the worker node being introduced to the cluster.

PLAY RECAP *******************************************************************************************************
kube-0                     : ok=53   changed=1    unreachable=0    failed=0    skipped=30   rescued=0    ignored=0
kube-1                     : ok=40   changed=1    unreachable=0    failed=0    skipped=35   rescued=0    ignored=0
kube-2                     : ok=42   changed=10   unreachable=0    failed=0    skipped=35   rescued=0    ignored=0