homeserver/roles/PyratLabs.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).
```yaml
---
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.
```yaml
---
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.
```text
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
```