k3s cluster on multipass instances

This script will create a configurable amount of instances using multipass, install k3s server(s) (HA using embedded etcd), and add the agent instances to the cluster.

Requirements

• multipass (See multipass: Install Multipass)

This is tested on MacOS, Ubuntu Linux 20.04 and Windows 10.

Running it

Clone this repo, and run the script:

bash multipass-k3s.sh

This will (defaults):

• Generate random name for your cluster (configurable using NAME)
• Create init-cloud-init file for server to install the first k3s server with embedded etcd (contains --cluster-init to activate embedded etcd)
• Create one instance for the first server with 2 CPU (SERVER_CPU_MACHINE), 10G disk (SERVER_DISK_MACHINE) and 1G of memory (SERVER_MEMORY_MACHINE) using Ubuntu focal (IMAGE)
• Create cloud-init file for server to install additional k3s servers with embedded etcd.
• Create one instance for additional server (configurable using SERVER_COUNT_MACHINE)
• Create cloud-init file for agent to join the cluster.
• Create one machine (configurable using AGENT_COUNT_MACHINE) with 1 CPU (AGENT_CPU_MACHINE), 3G disk (AGENT_DISK_MACHINE) and 512M of memory (AGENT_MEMORY_MACHINE) using Ubuntu focal (IMAGE)
• Wait for the nodes to be joined to the cluster
• Optionally merge the generated kubeconfig with the existing $KUBECONFIG (MERGE_KUBECONFIG)

Quickstart Ubuntu 20.04 droplet

sudo snap install multipass
wget https://raw.githubusercontent.com/superseb/multipass-k3s/master/multipass-k3s.sh
bash multipass-k3s.sh
curl -Lo /usr/local/bin/kubectl https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl
chmod +x /usr/local/bin/kubectl
kubectl --kubeconfig *-kubeconfig.yaml get nodes

Clean up

The files that are created are:

• $NAME-agent-cloud-init.yaml
• $NAME-cloud-init.yaml
• $NAME-kubeconfig.yaml
• $NAME-kubeconfig-orig.yaml
• $NAME-kubeconfig-backup.yaml (if MERGE_KUBECONFIG is set)
• $NAME-kubeconfig-merged.yaml (if MERGE_KUBECONFIG is set)

You can clean up the instances by running multipass delete k3s-server-$NAME-1 --purge and multipass delete k3s-agent-$NAME-{1,2,3} or (WARNING this deletes and purges all instances): multipass delete --all --purge