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

docs/devel/README.md

@@ -31,4 +31,6 @@ Docs in this directory relate to developing Kubernetes.
 
 * **Faster PR reviews** ([faster_reviews.md](faster_reviews.md)): How to get faster PR reviews.
 
+* **Getting Recent Builds** ([getting-builds.md](getting-builds.md)): How to get recent builds including the latest builds to pass CI.
+
 [![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/docs/devel/README.md?pixel)]()

docs/devel/getting-builds.md

+# Getting Kubernetes Builds
+
+You can use [hack/get-build.sh](../../hack/get-build.sh) to or use as a reference on how to get the most recent builds with curl. With `get-build.sh` you can grab the most recent stable build, the most recent release candidate, or the most recent build to pass our ci and gce e2e tests (essentially a nightly build).
+
+```
+usage:
+  ./hack/get-build.sh [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
+```
+
+You can also use the gsutil tool to explore the Google Cloud Storage release bucket. Here are some examples:
+```
+gsutil cat gs://kubernetes-release/ci/latest.txt          # output the latest ci version number
+gsutil cat gs://kubernetes-release/ci/latest-green.txt    # output the latest ci version number that passed gce e2e
+gsutil ls gs://kubernetes-release/ci/v0.20.0-29-g29a55cc/ # list the contents of a ci release
+gsutil ls gs://kubernetes-release/release                 # list all official releases and rcs
+```
+
+
+[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/docs/devel/getting-builds.md?pixel)]()

hack/get-build.sh

+#!/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}"