Version: 0.5.6

k3s Single Node on Aruba Cloud

Deploy a production-ready k3s single-node Kubernetes cluster on Aruba Cloud using Terraform and cloud-init. Includes the built-in Traefik ingress controller — no manual configuration required.

Provider version: arubacloud/arubacloud ~> 1.0 | Terraform: ≥ 1.9

Introduction

k3s is a lightweight, CNCF-certified Kubernetes distribution packaged as a single binary. It is ideal for edge computing, homelabs, CI environments, and small production workloads. This example provisions a single-node k3s cluster on Aruba Cloud with:

A CloudServer VM (CSO4A8 — 4 vCPU / 8 GB) running k3s, fully bootstrapped by cloud-init
The built-in Traefik v2 ingress controller for routing HTTP/HTTPS traffic to services
A dedicated VPC, subnet, and security group via the shared network module
An Elastic IP pinned to the node for stable external access
The Kubernetes API server pre-configured with the node's Elastic IP as a TLS SAN — so kubectl works immediately from your laptop without certificate errors
A ready-to-use kubeconfig placed in ~ubuntu/.kube/config on the node after boot

Architecture Overview

k3s runs as a single systemd service combining the control plane and worker node. Traefik is installed by k3s as a DaemonSet and handles all Ingress resources.

Infrastructure Created

Resource	Name pattern	Description
`arubacloud_project`	`k3s-prod`	Project container
`arubacloud_vpc`	`k3s-prod-vpc`	Virtual Private Cloud
`arubacloud_subnet`	`k3s-prod-subnet`	Basic subnet
`arubacloud_securitygroup`	`k3s-prod-vm-sg`	Security group
`arubacloud_securityrule`	`k3s-prod-vm-ssh`	SSH ingress (restricted CIDR)
`arubacloud_securityrule`	`k3s-prod-vm-http`	HTTP ingress (0.0.0.0/0)
`arubacloud_securityrule`	`k3s-prod-vm-https`	HTTPS ingress (0.0.0.0/0)
`arubacloud_securityrule`	`k3s-prod-vm-k8s-api`	Kubernetes API ingress (restricted CIDR)
`arubacloud_elasticip`	`k3s-prod-vm-eip`	Node public IP
`arubacloud_blockstorage`	`k3s-prod-boot`	80 GB boot disk (Performance)
`arubacloud_keypair`	`k3s-prod-keypair`	SSH public key
`arubacloud_cloudserver`	`k3s-prod-vm`	CloudServer VM

VM Sizing Recommendation

Workload	vCPU	RAM	Disk	Flavor
Dev / CI / low-traffic	4	8 GB	80 GB	`CSO4A8` (default)
Medium production	8	16 GB	100 GB	`CSO8A16`

A single-node cluster cannot reschedule pods on failure. For high availability, consider a multi-node setup (see the k3s HA example in Phase 3).

Estimated Monthly Cost

Approximate prices for ITBG-Bergamo, hourly billing. Actual prices may vary.

Resource	Spec	Est. cost/mo
CloudServer VM	CSO4A8 — 4 vCPU / 8 GB	~€36
Boot disk	80 GB Performance	~€10
Elastic IP	—	~€3
Total		~€49/mo

Requirements

Terraform ≥ 1.9
ArubaCloud Terraform Provider ~> 1.0
An ArubaCloud account with OAuth2 API credentials
An SSH key pair
kubectl installed locally to interact with the cluster

Variables

Required

Variable	Description
`arubacloud_client_id`	ArubaCloud OAuth2 client ID
`arubacloud_client_secret`	ArubaCloud OAuth2 client secret
`ssh_public_key`	SSH public key content

Optional

Variable	Default	Description
`app_name`	`"k3s"`	Short name used in all resource names
`environment`	`"prod"`	Environment label
`location`	`"ITBG-Bergamo"`	ArubaCloud region
`zone`	`"ITBG-1"`	Availability zone
`billing_period`	`"Hour"`	`"Hour"` or `"Month"`
`vm_flavor`	`"CSO4A8"`	CloudServer flavor
`vm_image`	`"LU22-001"`	Boot disk image (Ubuntu 22.04 LTS)
`vm_disk_size_gb`	`80`	Boot disk size in GB
`ssh_cidr`	`"0.0.0.0/0"`	CIDR for SSH — restrict to your IP in production
`api_cidr`	`"0.0.0.0/0"`	CIDR for Kubernetes API (port 6443) — restrict to your IP in production
`k3s_version`	`"v1.32.3+k3s1"`	k3s release — check github.com/k3s-io/k3s/releases
`cluster_domain`	`""`	Optional DNS name added as TLS SAN to the API server certificate

Outputs

Output	Description
`vm_public_ip`	Public IP address of the k3s node
`api_endpoint`	Kubernetes API server URL
`ssh_command`	SSH command to connect to the node
`kubeconfig_cmd`	One-liner to fetch the kubeconfig to your local machine

Deployment Instructions

1. Clone and navigate

git clone https://github.com/arubacloud/terraform-arubacloud-examples.git
cd terraform-arubacloud-examples/k3s-single

2. Configure variables

cp terraform.tfvars.example terraform.tfvars

Edit terraform.tfvars with your credentials and SSH key.

3. Initialize and deploy

terraform init
terraform plan
terraform apply

Bootstrap takes approximately 3–5 minutes — k3s installs fast since it is a single binary.

4. Fetch kubeconfig

# Copy the one-liner from outputs:
terraform output -raw kubeconfig_cmd | bash

# Or manually:
ssh ubuntu@$(terraform output -raw vm_public_ip) \
  'cat ~/.kube/config' > ~/.kube/k3s-arubacloud.yaml
export KUBECONFIG=~/.kube/k3s-arubacloud.yaml

5. Verify the cluster

kubectl get nodes
# NAME          STATUS   ROLES                  AGE   VERSION
# k3s-prod-vm   Ready    control-plane,master   2m    v1.32.3+k3s1

kubectl get pods -A
# Traefik, CoreDNS, and metrics-server should all be Running.

6. Deploy a workload

kubectl create deployment hello --image=nginx --replicas=1
kubectl expose deployment hello --port=80 --type=ClusterIP

# Create an Ingress to route external traffic:
cat <<EOF | kubectl apply -f -
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: hello
  annotations:
    traefik.ingress.kubernetes.io/router.entrypoints: web
spec:
  rules:
  - http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: hello
            port:
              number: 80
EOF

curl http://$(terraform output -raw vm_public_ip)

Destroy Instructions

terraform destroy

All cloud resources are deleted. Any data stored in PersistentVolumes on the boot disk is lost.

Security Recommendations

Restrict api_cidr to your IP. Exposing port 6443 to 0.0.0.0/0 allows anyone to attempt authentication against the API. Set api_cidr = "your.ip/32".
Restrict ssh_cidr to your IP. Set ssh_cidr = "your.ip/32".
Rotate the node token periodically. The k3s node token lives at /var/lib/rancher/k3s/server/node-token. Keep it secret.
Use RBAC for workloads. k3s ships with RBAC enabled. Create service accounts with least-privilege roles for each application.
Enable TLS for Ingress. Use cert-manager with Let's Encrypt to provision certificates for your Ingress resources, or configure Traefik's built-in ACME support.

Upgrade Considerations

k3s upgrade

k3s can be upgraded in-place using the same install script with a new version:

ssh ubuntu@$(terraform output -raw vm_public_ip)
curl -sfL https://get.k3s.io | INSTALL_K3S_VERSION="vX.Y.Z+k3s1" sh -

For zero-downtime upgrades in production, use the System Upgrade Controller.

Changing the node flavor

Changing vm_flavor or vm_disk_size_gb in terraform.tfvars and running terraform apply will replace the VM. Back up all PersistentVolume data first.

Troubleshooting

k3s is not running after apply

ssh ubuntu@$(terraform output -raw vm_public_ip)
sudo systemctl status k3s
sudo journalctl -u k3s -n 100
sudo tail -f /var/log/cloud-init-output.log

kubectl returns certificate error

The API server certificate includes the node's Elastic IP as a SAN. If you set cluster_domain, ensure that DNS resolves to the Elastic IP and use the domain in your kubeconfig server URL.

Pods stuck in Pending

Check node resources:

kubectl describe node
kubectl get events --sort-by='.lastTimestamp'

Single-node clusters run both control-plane and workloads on the same VM — ensure the flavor has enough memory for your workloads.

Introduction​

Architecture Overview​

Infrastructure Created​

VM Sizing Recommendation​

Estimated Monthly Cost​

Requirements​

Variables​

Required​

Optional​

Outputs​

Deployment Instructions​

1. Clone and navigate​

2. Configure variables​

3. Initialize and deploy​

4. Fetch kubeconfig​

5. Verify the cluster​

6. Deploy a workload​

Destroy Instructions​

Security Recommendations​

Upgrade Considerations​

k3s upgrade​

Changing the node flavor​

Troubleshooting​

k3s is not running after apply​

kubectl returns certificate error​

Pods stuck in Pending​

References​