Use kubecfg against GKE cluster

gke-kubecfg.sh

#!/bin/bash

# Copyright 2014 Google Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

set -o errexit
set -o nounset
set -o pipefail

PROJECT=
ZONE=
CLUSTER=

usage() {
  cat >&2 <<EOF
This scripts helps you use kubecfg against a GKE cluster.

This assumes you've interacted with your GKE cluster enough so that gcloud has
cached the important bits about the cluster.

Usage:
  $0 [--project=<project>] --zone <zone> --cluster-name <cluster> [kubecfg args]
EOF
  exit 1
}

[[ $# > 1 ]] || usage

if [[ -z "${PROJECT}" ]]; then
  PROJECT=$(gcloud config list project | tail -n 1 | cut -f 3 -d ' ')
fi

args=()
while [[ $# > 0 ]]; do
  key="$1"
  shift

  case $key in
    --project)
    PROJECT="$1"
    shift
    ;;
    --zone)
    ZONE="$1"
    shift
    ;;
    --cluster-name)
    CLUSTER="$1"
    shift
    ;;
    *)
    args+=("$key")
    ;;
  esac
done

[[ -n "${PROJECT}" && -n "${ZONE}" && -n "${CLUSTER}" ]] || usage

CONFIG_PATH="${HOME}/.config/gcloud/container/${PROJECT}.${ZONE}.${CLUSTER}"

[[ -d "${CONFIG_PATH}" ]] || {
  echo "Error finding config information for cluster." >&2
  echo "Looking in $CONFIG_PATH" >&2
  exit 2
}

ENDPOINT_IP=$(cat "${CONFIG_PATH}/cluster.json" | perl -n -e'/"endpoint": "(.*)"/ && print $1')

kubecfg -h https://${ENDPOINT_IP} \
  -auth "${CONFIG_PATH}/kubernetes_auth" \
  -certificate_authority "${CONFIG_PATH}/ca.crt" \
  -client_certificate "${CONFIG_PATH}/kubecfg.crt" \
  -client_key "${CONFIG_PATH}/kubecfg.key" \
  "${args[@]:+${args[@]}}"