VPA: add k8s deps update script

vertical-pod-autoscaler/e2e/go.mod

@@ -1,3 +1,6 @@
+// for updating kubernetes dependencies, use `autoscaler/vertical-pod-autoscaler/hack/update-kubernetes-deps-in-e2e.sh`
+// for any other update, use standard `go mod` commands
+
 module k8s.io/autoscaler/vertical-pod-autoscaler/e2e
 
 go 1.12

vertical-pod-autoscaler/hack/update-kubernetes-deps-in-e2e.sh

@@ -0,0 +1,64 @@
+#!/usr/bin/env bash
+
+# Copyright 2019 The Kubernetes Authors.
+#
+# 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.
+
+# Usage:
+# $ K8S_TAG=<k8s_tag> ./hack/update-kubernetes-deps-in-e2e.sh
+# K8S_TAG - k8s version to use for the dependencies update.
+# Suggested format is K8S_TAG=v1.10.3
+
+set -eou errexit pipefail nounset
+
+K8S_TAG=${K8S_TAG:-v1.16.2}
+K8S_TAG=${K8S_TAG#v}
+
+export GO111MODULE=on
+
+function update_deps() {
+    # list staged k8s.io repos   
+    MODS=($(
+        curl -sS https://raw.githubusercontent.com/kubernetes/kubernetes/v${K8S_TAG}/go.mod |
+        sed -n 's|.*k8s.io/\(.*\) => ./staging/src/k8s.io/.*|k8s.io/\1|p'
+    ))
+
+    # get matching tag for each staged k8s.io repo
+    for MOD in "${MODS[@]}"; do
+        V=$(
+            go mod download -json "${MOD}@kubernetes-${K8S_TAG}" |
+            sed -n 's|.*"Version": "\(.*\)".*|\1|p'
+        )
+        go mod edit "-replace=${MOD}=${MOD}@${V}"
+    done
+
+    # update k8s.io/kubernetes to desired tag
+    go get "k8s.io/kubernetes@v${K8S_TAG}"
+}
+
+
+# execute in subshell to keep CWD even in case of failures
+(
+    # find script directory invariantly of CWD
+    DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+
+    # cd to e2e tests
+    cd $DIR/../e2e
+
+    # update k8s deps in e2e
+    update_deps
+
+    # tidy and vendor modules
+    go mod tidy
+    go mod vendor
+)