From 7d40e070db29ab14e3d437a81a46c1b87497b6b5 Mon Sep 17 00:00:00 2001
From: Madhav Jivrajani <madhav.jiv@gmail.com>
Date: Tue, 12 Mar 2024 15:15:04 +0530
Subject: [PATCH] .*: add verify script for go directive changes

This commit adds a script that checks the changed version in
the go.mod file with a certain maximum version that the go
directive can have.

We set the maximum version of the go directive as 1.20 here
because the oldest go directive that exists on our supported
release branches in k/k is 1.20.

Signed-off-by: Madhav Jivrajani <madhav.jiv@gmail.com>
---
 Makefile                    |  8 +++++-
 hack/verify-go-directive.sh | 57 +++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100755 hack/verify-go-directive.sh

diff --git a/Makefile b/Makefile
index 26b24faa..1a6bbed6 100644
--- a/Makefile
+++ b/Makefile
@@ -4,6 +4,12 @@ all:
 
 test:
 	go test -race ./...
-	./hack/verify-examples.sh
 	go -C v2 test -race ./...
 	(cd v2 && ./hack/verify-examples.sh)
+
+# We verify for the maximum version of the go directive as 1.20
+# here because the oldest go directive that exists on our supported
+# release branches in k/k is 1.20.
+verify:
+	./hack/verify-examples.sh
+	./hack/verify-go-directive.sh 1.20
diff --git a/hack/verify-go-directive.sh b/hack/verify-go-directive.sh
new file mode 100755
index 00000000..7bbb9037
--- /dev/null
+++ b/hack/verify-go-directive.sh
@@ -0,0 +1,57 @@
+#!/usr/bin/env bash
+
+# Copyright 2024 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.
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+function usage {
+  local script="$(basename $0)"
+
+  echo >&2 "Usage: ${script} <maximum go directive>
+This script should be run at the root of a module.
+
+Compare the go directive in the local working copy's go.mod
+to the specified maximum version it can be. Versions provided
+here are of the form 1.x.y, without the 'go' prefix.
+Examples:
+  ${script} 1.20
+  ${script} 1.21.6
+"
+  exit 1
+}
+
+max="$1"
+# If max is empty, print usage and error
+if [[ -z "${max}" ]]; then
+  usage;
+fi
+
+# Don't specify the version with the go prefix, just 1.x.y will do.
+if [[ ! "${max}" =~ ^[0-9]\.[0-9]+(\.[0-9]+)?$ ]]; then
+    usage
+fi
+
+current=$(awk '/^go / {print $2;}' go.mod)
+if [[ -z "${current}" ]]; then
+  echo >&2 "FAIL: could not get value of go directive from go.mod"
+  exit 1
+fi
+
+if ! printf '%s\n' "${current}" "${max}" | sort --check=silent --version-sort; then
+    echo >&2 "FAIL: current Go directive ${current} is greater than ${max}"
+    exit 1
+fi