Connects kubectl with a new cluster. Based on https://github.com/hobby-kube/provisioning/blob/master/service/kubernetes/kubectl.tf

kubectl-connect.sh

#!/bin/bash

###################
## SAMPLE OUTPUT ##
###################

: <<'END'
Press Ctrl-C to exit at any point

Please enter a name for this cluster: prod1
Use "prod1"? (Y/n): y

What is the IP address of the master node? 159.0.0.0
Use "159.0.0.0"? (Y/n): y

Select a connection port (default is 6443):

Name: prod1
IP: 159.0.0.0
Port: 6443

The following will be done:

| mkdir -p /Users/rob/.kube/prod1
|
| scp -oStrictHostKeyChecking=no \
|   root@159.0.0.0:/etc/kubernetes/pki/{apiserver-kubelet-client.key,apiserver-kubelet-client.crt,ca.crt} \
|   /Users/rob/.kube/prod1
|
| kubectl config set-cluster prod1 \
| --certificate-authority=/Users/rob/.kube/prod1/ca.crt \
| --server=https://159.0.0.0:6443 \
| --embed-certs=true
|
| kubectl config set-credentials prod1-admin \
|   --client-key=/Users/rob/.kube/prod1/apiserver-kubelet-client.key \
|   --client-certificate=/Users/rob/.kube/prod1/apiserver-kubelet-client.crt \
|   --embed-certs=true
|
| kubectl config set-context prod1 \
|   --cluster=prod1 \
|   --user=prod1-admin
|
| kubectl config use-context prod1
| kubectl get nodes

"yes" to execute:
END

function promptConfirm () {
  local return_var=$2
  local input=""

  echo
  while [ "$input" = "" ]
  do
    read -p "$1 " input
    if [ "$input" = "" ] || [[ $input =~ [[:space:]] ]]
    then
      input=""
    else
      read -p "Use \"$input\"? (Y/n): " -n 1 -r
      if [[ $REPLY =~ ^[Nn]$ ]]
      then
        input=""
      fi
    fi
  done

  eval $return_var="'$input'"
}

function promptAccept () {
  local return_var=$2
  local val=""

  while [ "$val" = "" ]
  do
    echo
    read -p "$1 " val
    val=${val:-6443}

    if [[ $val =~ [[:space:]] ]]
    then
      echo Value cannot contain spaces
      val=""
    fi

  done

  eval $return_var="'$val'"
}

function to_int {
  local -i num="10#${1}"
  echo "${num}"
}

function port_is_ok {
  local return_var=$2
  local input="$1"
  local -i port_num=$(to_int "${input}" 2>/dev/null)

  if (( $port_num < 1 || $port_num > 65535 )) ; then
    echo Not a valid port number
    eval $return_var="''"
  else
    eval $return_var="'$port_num'"
  fi
}


echo "Press Ctrl-C to exit at any point"
promptConfirm "Please enter a name for this cluster:" CLUSTER_NAME

echo
promptConfirm "What is the IP address of the master node?" MASTER_IP

echo
while [ "$PORT" = "" ]
do
  promptAccept "Select a connection port (default is 6443):" PORT
  if [ "$PORT" = "" ]
  then
    PORT=6443
  fi
  port_is_ok $PORT PORT
done

echo
echo Name: $CLUSTER_NAME
echo IP: $MASTER_IP
echo Port: $PORT

echo "
The following will be done:

| mkdir -p $HOME/.kube/$CLUSTER_NAME
|
| scp -oStrictHostKeyChecking=no \\
|   root@$(echo "$MASTER_IP"):/etc/kubernetes/pki/{apiserver-kubelet-client.key,apiserver-kubelet-client.crt,ca.crt} \\
|   $(echo "$HOME")/.kube/$(echo "$CLUSTER_NAME")
|
| kubectl config set-cluster $(echo "$CLUSTER_NAME") \\
| --certificate-authority=$(echo "$HOME")/.kube/$(echo "$CLUSTER_NAME")/ca.crt \\
| --server=https://$(echo "$MASTER_IP"):$(echo "$PORT") \\
| --embed-certs=true
|
| kubectl config set-credentials $(echo "$CLUSTER_NAME")-admin \\
|   --client-key=$(echo "$HOME")/.kube/$(echo "$CLUSTER_NAME")/apiserver-kubelet-client.key \\
|   --client-certificate=$(echo "$HOME")/.kube/$(echo "$CLUSTER_NAME")/apiserver-kubelet-client.crt \\
|   --embed-certs=true
|
| kubectl config set-context $(echo "$CLUSTER_NAME") \\
|   --cluster=$(echo "$CLUSTER_NAME") \\
|   --user=$(echo "$CLUSTER_NAME")-admin
|
| kubectl config use-context $(echo "$CLUSTER_NAME")
| kubectl get nodes"


echo
read -p "\"yes\" to execute: " RUN_IT
if [ "$RUN_IT" = "yes" ]
then
  mkdir -p $HOME/.kube/$CLUSTER_NAME

  scp -oStrictHostKeyChecking=no \
    root@$MASTER_IP:/etc/kubernetes/pki/{apiserver-kubelet-client.key,apiserver-kubelet-client.crt,ca.crt} \
    $HOME/.kube/$CLUSTER_NAME/

  kubectl config set-cluster $CLUSTER_NAME \
  --certificate-authority=$HOME/.kube/$CLUSTER_NAME/ca.crt \
  --server=https://$MASTER_IP:$PORT \
  --embed-certs=true

  kubectl config set-credentials $CLUSTER_NAME-admin \
    --client-key=$HOME/.kube/$CLUSTER_NAME/apiserver-kubelet-client.key \
    --client-certificate=$HOME/.kube/$CLUSTER_NAME/apiserver-kubelet-client.crt \
    --embed-certs=true

  kubectl config set-context $CLUSTER_NAME \
    --cluster=$CLUSTER_NAME \
    --user=$CLUSTER_NAME-admin

  kubectl config use-context $CLUSTER_NAME
  kubectl get nodes
fi