#!/bin/bash
concurrency_count=2
# Ensure to have correct current-context on your kubeconfig
KUBECONFIG=~/.kube/config

nodes_draining(){
  ps -ef |grep "[k]ubectl drain"
  return $?
}

wait_for_replace_confirmation(){
  confirmation=true
  while $confirmation
  do read -r -p "Please replace nodes and confirm completion [Y/yes]" input

    case $input in
    [yY][eE][sS]|[yY])
      echo "Replace confirmed. Proceeding"
      confirmation=false
      ;;
    *)
      echo "Invalid input..."
      ;;
    esac
  done
}

node_private_ips(){
  private_ips=()
  for node in "${active_rolling_nodes[@]}"; do
    internal_ip="$(kubectl --kubeconfig=${KUBECONFIG}  describe node $node |grep InternalIP |awk '{print $2}')"
    private_ips=("${private_ips[@]}" "$internal_ip")
  done
  echo ${private_ips[@]}
}

roll_nodeset(){
    echo "Draining Nodes: ${active_rolling_nodes[@]}"
    while nodes_draining; do
      echo "Waiting on draining nodes..."
      sleep 5
    done
    echo "Please Execute Node Replace: $(node_private_ips)"
    wait_for_replace_confirmation
    echo "Uncordoning ${#active_rolling_nodes[@]} nodes"
}

kube_nodes=($(kubectl --kubeconfig=${KUBECONFIG}  get nodes |tail -n +2 |grep -v master |awk '{print $1}'))
active=1
active_rolling_nodes=()
for node in "${kube_nodes[@]}"; do
  echo "CurrentNode: ${node}"
  if [[ $active < $concurrency_count ]]; then
    kubectl --kubeconfig=${KUBECONFIG}  drain --ignore-daemonsets ${node} &
    active_rolling_nodes=("${active_rolling_nodes[@]}" "$node")
    active=$(expr $active + 1)
  else
    kubectl --kubeconfig=${KUBECONFIG}  drain --ignore-daemonsets ${node}
    active_rolling_nodes=("${active_rolling_nodes[@]}" "$node")
    roll_nodeset $active_rolling_nodes
    active_rolling_nodes=()
    active=1
  fi
done

roll_nodeset $active_rolling_nodes