add a tool in cmd/ to check links in go file. Currently it's only used to check the links in api descriptions (pkg/api/.../types.go).

hack/verify-linkcheck.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+
+# Copyright 2014 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
+
+KUBE_ROOT=$(dirname "${BASH_SOURCE}")/..
+source "${KUBE_ROOT}/hack/lib/init.sh"
+
+kube::golang::setup_env
+linkcheck=$(kube::util::find-binary "linkcheck")
+
+if [[ ! -x "$linkcheck" ]]; then
+  {
+    echo "It looks as if you don't have a compiled linkcheck binary"
+    echo
+    echo "If you are running from a clone of the git repo, please run"
+    echo "'./hack/build-go.sh cmd/linkcheck'."
+  } >&2
+  exit 1
+fi
+
+TYPEROOT="${KUBE_ROOT}/pkg/api/"
+"${linkcheck}" "--root-dir=${TYPEROOT}" "--repo-root=${KUBE_ROOT}" "--file-suffix=types.go" "--prefix=http://releases.k8s.io/HEAD" && ret=0 || ret=$?
+if [[ $ret -eq 1 ]]; then
+  echo "links in ${TYPEROOT} is out of date."
+  exit 1
+fi
+if [[ $ret -gt 1 ]]; then
+  echo "Error running linkcheck"
+  exit 1
+fi