Create kubernetes cluster using multipass instances(kvm/qemu) with microk8s ir k3s kubernetes distribution

readme.md

Kubernetes development environment with multipass and k3s/microk8s

This is a script to create multipass instances to deploy k3s or microk8s kubernetes distribution

Prerequisites

In order to use this script, you need to install multipass snap package, provided by canonical. To install execute the follow command

sudo snap install multipass

Avaliable variables

Variable	Description	Default value
MASTER_NODE_COUNT	The number of master nodes that will be avaliable	1
MASTER_NODE_PREFIX	The prefix to use in master instances name	master
WORKER_NODE_COUNT	The number of worker nodes that will be avaliable	2
WORKER_NODE_PREFIX	The prefix to use in worker instances name	worker
KUBERNETES_DISTRIBUTION	The kubernetes distribution to use. For now only k3s and microk8s	k3s

How to

First of all, if you want to get all fixes for bugs, i recommend that you clone this gist. For that, execute the command above:

git clone git@gist.github.com:a11088b3145e91d2d4d766b49ebe0d81.git kubernetes-bootstrap

To use the default options(one master node and two worker nodes), execute the script in cloned folder

./kubernetes-bootstrap.sh

To change any option, just precede the script call with specific variable.

WORKER_NODE_COUNT=4 MASTER_NODE_PREFIX=controller KUBERNETES_DISTRIBUTION=microk8s ./kubernetes-bootstrap.sh

To interact with the cluster, use one of the above:

kubectl --kubeconfig=${HOME}/.kube/k3s.yaml get nodes

kubectl --kubeconfig=${HOME}/.kube/microk8s.yaml get nodes

NAME           STATUS   ROLES    AGE    VERSION
worker-2       Ready    <none>   99m    v1.17.2+k3s1
worker-3       Ready    <none>   98m    v1.17.2+k3s1
controller-1   Ready    master   103m   v1.17.2+k3s1
worker-4       Ready    <none>   96m    v1.17.2+k3s1

TODO

[ ] Enable multi master cluster

kubernetes-bootstrap.sh

#!/usr/bin/env bash

set -euxo pipefail

: ${MASTER_NODE_COUNT:=1}
: ${MASTER_NODE_PREFIX:=master}

: ${WORKER_NODE_COUNT:=2}
: ${WORKER_NODE_PREFIX:=worker}

: ${KUBERNETES_DISTRIBUTION:='k3s'}

#############


function multipass_instance_exists(){
  INSTANCE_NAME=$1
  AVALIABLE_INSTANCES=(`multipass list | awk '{print $1}' | sed 1d`)
  
  for AVALIABLE_INSTANCE in "${AVALIABLE_INSTANCES[@]}"; do
    if [ "$AVALIABLE_INSTANCE" == "$INSTANCE_NAME" ]; then 
      return 1
    fi
  done
}

function create_master_node() {
  for ((counter=1; counter<=$MASTER_NODE_COUNT; counter++)); do
    MASTER_NODE_NAME=$1
    multipass launch --name $MASTER_NODE_NAME --cpus 1 --mem 1G --disk 3G
  done
}

function get_master_address() {
  echo "https://$(multipass info $MASTER_NODE_NAME | grep "IPv4" | awk -F' ' '{print $2}'):6443"
}

function get_master_token() {
  if [ "$KUBERNETES_DISTRIBUTION" == "k3s" ]; then
    echo "$(multipass exec $MASTER_NODE_NAME -- /bin/bash -c "sudo cat /var/lib/rancher/k3s/server/node-token")"
  elif [ "$KUBERNETES_DISTRIBUTION" == "microk8s" ]; then
    echo "$(multipass exec ${MASTER_NODE_NAME} -- /snap/bin/microk8s.add-node | grep "Join node with" | awk -F 'Join node with: ' '{ print $2 }' | awk -F ' ' '{ print $2}' | tr -d '\r')"
  fi
}

function create_worker_node() {
  WORKER_NODE_NAME=$1
  multipass launch --name $WORKER_NODE_NAME --cpus 1 --mem 1G --disk 3G
}

function deploy_kubernetes_distribution() {
  NODE_TYPE=$1
  INSTANCE_NAME=$2
  
  if [ "$KUBERNETES_DISTRIBUTION" == "k3s" ]; then
    if [ "$NODE_TYPE" == "master" ]; then
      deploy_k3s_distribution_master $INSTANCE_NAME
      sleep 10s
    elif [ "$NODE_TYPE" == "worker" ]; then
      deploy_k3s_distribution_worker $INSTANCE_NAME
    fi
  elif [ "$KUBERNETES_DISTRIBUTION" == "microk8s" ]; then
    if [ "$NODE_TYPE" == "master" ]; then
      deploy_microk8s_distribution_master $INSTANCE_NAME
      sleep 10s
    elif [ "$NODE_TYPE" == "worker" ]; then
      deploy_microk8s_distribution_worker $INSTANCE_NAME
    fi
  fi
}

function deploy_k3s_distribution_master() {
  INSTANCE_NAME=$1
  multipass exec $INSTANCE_NAME -- /bin/bash -c "curl -sfL https://get.k3s.io | K3S_KUBECONFIG_MODE="644" sh -"
}

function deploy_k3s_distribution_worker() {
  INSTANCE_NAME=$1
  MASTER_NODE_URL=`get_master_address`
  MASTER_NODE_TOKEN=`get_master_token`

  multipass exec $INSTANCE_NAME -- /bin/bash -c "curl -sfL https://get.k3s.io | K3S_TOKEN=${MASTER_NODE_TOKEN} K3S_URL=${MASTER_NODE_URL} sh -"
}

function deploy_microk8s_distribution_master() {
  INSTANCE_NAME=$1

  multipass exec $INSTANCE_NAME -- /bin/bash -c "sudo snap install microk8s --classic --channel=1.17/stable"
  multipass exec $INSTANCE_NAME -- /bin/bash -c "sudo usermod -a -G microk8s ubuntu"
}

function deploy_microk8s_distribution_worker() {
  INSTANCE_NAME=$1
  MASTER_NODE_TOKEN=`get_master_token`

  multipass exec $INSTANCE_NAME -- /bin/bash -c "sudo snap install microk8s --classic --channel=1.17/stable"
  multipass exec $INSTANCE_NAME -- /bin/bash -c "sudo usermod -a -G microk8s ubuntu"
  multipass exec $INSTANCE_NAME -- /bin/bash -c "/snap/bin/microk8s.join ${MASTER_NODE_TOKEN}"
}

function copy_config_file() {
  INSTANCE_NAME=$1
  
  if [ "$KUBERNETES_DISTRIBUTION" == "k3s" ]; then
    MASTER_NODE_URL=`get_master_address`

    multipass copy-files $INSTANCE_NAME:/etc/rancher/k3s/k3s.yaml ${HOME}/.kube/k3s.yaml
    sed -ie s,https://127.0.0.1:6443,${MASTER_NODE_URL},g ${HOME}/.kube/k3s.yaml
  elif [ "$KUBERNETES_DISTRIBUTION" == "microk8s" ]; then
    multipass exec $INSTANCE_NAME -- /bin/bash -c /snap/bin/microk8s.config > ${HOME}/.kube/microk8s.yaml
  fi
}

function deploy_and_configure_nodes() {
  FIRST_MASTER_NOME="$MASTER_NODE_PREFIX-1"

  # Deploy and configure MASTER nodes
  for ((counter=1; counter<=$MASTER_NODE_COUNT; counter++))
  do
    MASTER_NODE_NAME=$MASTER_NODE_PREFIX-$counter
    
    if multipass_instance_exists $MASTER_NODE_NAME; then
      create_master_node $MASTER_NODE_NAME
      deploy_kubernetes_distribution master $MASTER_NODE_NAME
      copy_config_file $MASTER_NODE_NAME
    fi
  done
  
  #Deploy and configure WORKER nodes
  for ((counter=1; counter<=$WORKER_NODE_COUNT; counter++))
  do
    WORKER_NODE_NAME=$WORKER_NODE_PREFIX-$counter
    
    if multipass_instance_exists $WORKER_NODE_NAME; then
      create_worker_node $WORKER_NODE_NAME
      deploy_kubernetes_distribution worker $WORKER_NODE_NAME
    fi
  done
}

function init() {
  deploy_and_configure_nodes
}

init;