add documentation and script on how to get recent and "nightly" builds

hack/get-build.sh

@@ -0,0 +1,70 @@
+#!/bin/bash
+
+# Copyright 2015 The Kubernetes Authors 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
+
+declare -r KUBE_RELEASE_BUCKET_URL="https://storage.googleapis.com/kubernetes-release"
+declare -r KUBE_TAR_NAME="kubernetes.tar.gz"
+
+usage() {
+	echo "usage:
+  $0 [stable|release|latest|latest-green]
+
+        stable:        latest stable version
+        release:       latest release candidate
+        latest:        latest ci build
+        latest-green:  latest ci build to pass gce e2e"
+}
+
+if [[ $# -ne 1 ]]; then
+    usage
+    exit 1
+fi
+
+case "$1" in
+  "latest")
+    # latest ci version is written in the latest.txt in the /ci dir
+    KUBE_TAR_RELATIVE_PATH="ci"
+    KUBE_VERSION_FILE="latest.txt"
+    ;;
+  "latest-green")
+    # latest ci version to pass gce e2e is written in the latest-green.txt in the /ci dir
+    KUBE_TAR_RELATIVE_PATH="ci"
+    KUBE_VERSION_FILE="latest-green.txt"
+    ;;
+  "stable")
+    # latest stable release version is written in the stable.txt file in the /release dir
+    KUBE_TAR_RELATIVE_PATH="release"
+    KUBE_VERSION_FILE="stable.txt"
+    ;;
+  "release")
+    # latest release candidate version is written in latest.txt in the /release dir
+    KUBE_TAR_RELATIVE_PATH="release"
+    KUBE_VERSION_FILE="latest.txt"
+    ;;
+  *)
+    usage
+    exit 1
+    ;;
+esac
+
+KUBE_BINARY_DIRECTORY="${KUBE_RELEASE_BUCKET_URL}/${KUBE_TAR_RELATIVE_PATH}"
+KUBE_VERSION=$(curl --silent --fail "${KUBE_BINARY_DIRECTORY}/${KUBE_VERSION_FILE}")
+KUBE_BINARY_PATH="${KUBE_BINARY_DIRECTORY}/${KUBE_VERSION}/${KUBE_TAR_NAME}"
+
+curl --fail -o kubernetes-${KUBE_VERSION}.tar.gz "${KUBE_BINARY_PATH}"