Set a current kubeconfig context only for the current shell session

kctx.bash

bash_setup() {
    cat <<SETUP
alias kctx='. $(readlink -f "$0")'
__kctx () { mapfile -t COMPREPLY < <(compgen -W "\$(kubectl config get-contexts -o name) --help --unset" -- "\${COMP_WORDS[1]}"); }
complete -F __kctx kctx
SETUP
}

usage() {
  cat <<EOF
usage: kctx [option] context
  -h, --help     show this message
  -u, --unset    back to global context
EOF
}

set_context_env() {
    local -r context=$1
    [[ -z $context ]] && { usage >&2; return 1; }

    kubectl config get-contexts "$context" >/dev/null || return

    cache=${XDG_CACHE_HOME:-$HOME/.cache}/kctx
    mkdir -p "$cache"

    export KUBECONFIG
    : "${KUBECONFIG:=$HOME/.kube/config}"
    context_config="$cache/${context}.yaml"

    if [[ ! -f $context_config ]]
    then
        cat >"$context_config" <<CONF
apiVersion: v1
kind: Config
current-context: $context
CONF
        chmod -w "$context_config"  # Prevent overwrites by kubectx etc.
    fi

    KUBECONFIG="$context_config:${KUBECONFIG/$cache\/*.yaml:}"
}

case $1 in
    -h|--help)
        usage
        ;;
    --bash-config)
        bash_setup
        ;;
    -u|--unset)
        KUBECONFIG="${KUBECONFIG/$cache\/*.yaml:}"
        ;;
    *)
        set_context_env "$1"
esac

Setup

The script needs to be sourced in order to be able to change the current shell environment. For this it's easiest to define a shell alias. An alias for bash is provided which you may add to your ~/.bashrc:

$ bash kctx.bash --bash-config >>~/.bashrc

Afterwards you should have a kctx alias available in a new bash session. Note: if you move the kctx.bash script to another path you need to regenerate the alias.

Usage

Call the kctx alias with a context name

$ kctx a-context

Switch back to global context with -u

$ kctx -u