kubeswitch.sh

#!/usr/bin/env bash

# Add it as a global executable
# curl -s https://raw.githubusercontent.com/JimCronqvist/ubuntu-scripts/master/kubeswitch.sh | sudo tee /usr/local/bin/kubeswitch >/dev/null && sudo chmod +x /usr/local/bin/kubeswitch


# 'select_option' from here: https://unix.stackexchange.com/a/415155
function select_option {

    # little helpers for terminal print control and key input
    ESC=$( printf "\033")
    cursor_blink_on()  { printf "$ESC[?25h"; }
    cursor_blink_off() { printf "$ESC[?25l"; }
    cursor_to()        { printf "$ESC[$1;${2:-1}H"; }
    print_option()     { printf "   $1 "; }
    print_selected()   { printf "  $ESC[7m $1 $ESC[27m"; }
    get_cursor_row()   { IFS=';' read -sdR -p $'\E[6n' ROW COL; echo ${ROW#*[}; }
    key_input()        {
                         read -s -n3 key 2>/dev/null >&2
                         if [[ $key = $ESC[A ]]; then echo up;    fi
                         if [[ $key = $ESC[B ]]; then echo down;  fi
                         if [[ $key = ""     ]]; then echo enter; fi
                       }

    # initially print empty new lines (scroll down if at bottom of screen)
    for opt; do printf "\n"; done

    # determine current screen position for overwriting the options
    local lastrow=`get_cursor_row`
    local startrow=$(($lastrow - $#))

    # ensure cursor and input echoing back on upon a ctrl+c during read -s
    trap "cursor_blink_on; stty echo; printf '\n'; exit" 2
    cursor_blink_off

    local selected=0
    while true; do
        # print options by overwriting the last lines
        local idx=0
        for opt; do
            cursor_to $(($startrow + $idx))
            if [ $idx -eq $selected ]; then
                print_selected "$opt"
            else
                print_option "$opt"
            fi
            ((idx++))
        done

        # user key control
        case `key_input` in
            enter) break;;
            up)    ((selected--));
                   if [ $selected -lt 0 ]; then selected=$(($# - 1)); fi;;
            down)  ((selected++));
                   if [ $selected -ge $# ]; then selected=0; fi;;
        esac
    done

    # cursor position back to normal
    cursor_to $lastrow
    printf "\n"
    cursor_blink_on

    return $selected
}


##
## Script start
##

CURRENT_CONTEXT="$(kubectl config current-context)"
CONTEXTS=( $(kubectl config get-contexts -o name | sort) )
CONTEXTS_WITH_DEFAULT=("${CONTEXTS[@]}")

for i in "${!CONTEXTS[@]}"; do
    if [[ ${CONTEXTS[$i]} == "${CURRENT_CONTEXT}" ]]; then
        CONTEXTS_WITH_DEFAULT[$i]="* ${CONTEXTS[$i]}"
    fi
done

echo ""
echo "Select a kubectl context:"
echo ""

select_option "${CONTEXTS_WITH_DEFAULT[@]}"
INDEX=$?
VALUE=${CONTEXTS[$INDEX]}

kubectl config use-context "${VALUE}"