add verify script to catch most validation mutations

hack/make-rules/verify.sh

@@ -80,6 +80,7 @@ QUICK_PATTERNS+=(
   "verify-vendor-licenses.sh"
   "verify-gofmt.sh"
   "verify-imports.sh"
+  "verify-non-mutating-validation.sh"
   "verify-pkg-names.sh"
   "verify-readonly-packages.sh"
   "verify-spelling.sh"

hack/verify-non-mutating-validation.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+# Copyright 2021 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.
+
+# This script checks that validation files do not mutate their inputs.
+# Usage: `hack/verify-non-mutating-validation.sh`.
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+KUBE_ROOT=$(dirname "${BASH_SOURCE[0]}")/..
+source "${KUBE_ROOT}/hack/lib/init.sh"
+
+mutationOutput=$(find . -name validation.go -print0 | xargs -0 egrep -n ' = old' | grep -v '// +k8s:verify-mutation:reason=clone' || true)
+foundMutation=${#mutationOutput}
+# when there's no match, there is a newline
+if [ "$foundMutation" -gt "1" ]; then
+  echo "${mutationOutput}"
+  echo "It looks like an assignment of a value using the old object.  This is a heuristic check.  If a mutation is happening in validation please fix it."
+  echo "If a mutation of arguments is not happening, you can exempt a line using '// +k8s:verify-mutation:reason=clone'."
+  exit 1
+fi
+
+mutationOutput=$(! find . -name validation.go -print0 | xargs -0 egrep -n 'old.* = ' | grep -v '// +k8s:verify-mutation:reason=clone' || true)
+foundMutation=${#mutationOutput}
+# when there's no match, there is a newline
+if [ "$foundMutation" -gt "1" ]; then
+  echo "${mutationOutput}"
+  echo "It looks like an assignment to the old object is happening.  This is a heuristic check.  If a mutation is happening in validation please fix it."
+  echo "If a mutation of arguments is not happening, you can exempt a line using '// +k8s:verify-mutation:reason=clone'."
+  exit 1
+fi