Set kubernets current-context from one of the contexts in the config file

kccontexts.sh

kccontexts() {
  # Works with kubectl v1.4.0 and the config file generated by gcloud containers clusters get-credentials
  # If you pass in an arg, then we will filter the contexts for that string
  
  # The following block creates a list of the contexts and filters if an argument
  # is passed in.
  if [[ $1 ]]
    then
      options=(`kubectl config get-contexts -o name | sort | grep $1`)
  else
    options=(`kubectl config get-contexts -o name | sort`)
  fi

  if [[ ${#options[@]} == 0 ]]
    then
      msg="No contexts found"
      if [[ $1 ]]
        then
          msg="$msg - check the string you are filtering with"
      else
        msg="$msg - either there are no contexts, or the config file is a different format than expected"
      fi
      echo $msg
      return 0
  fi

  current_context=`kubectl config current-context`
  echo "Currently using $current_context"
  echo "----------"

  # Walk through the contexts, and display them with a numeric choice
  for i in ${!options[@]}; do 
    printf "%3d%s) %s\n" $((i+1)) "${choices[i]:- }" "${options[i]}"
  done

  # Prompt for the number of the context to swith to
  prompt="Pick a Context(1-${#options[@]}):"
  read -rp "$prompt" num;
  
  # Confirm a valid input (numbers only, 0 < num < number of contexts)
  if [[ "$num" = '' ]] || [[ "$num" = *[![:digit:]]* ]] || (( $num <= 0 || $num > ${#options[@]} ))
    then
      echo "Invalid option: current context not changed";
      return 1
  else
    ((num--));
    msg="${options[num]}"

    echo "You are now using $msg"
    kubectl config use-context $msg;
    return 0
  fi
}