feat: add check metadata version CLI utility

This adds a CLI utility which given a version number will
check that there is a release series defined in a metadata file for
that version.

The main use case for this is a CI check. When building a release of a
provider that is for a new major or minor version its required that a
new release series is added to the providers metadata file. This ensures
that the correct version of the provider is installed when initializing
a management cluster.

A common failure for release pipelines is that the metadata file hasn't
been updated.

Signed-off-by: Richard Case <[email protected]>

Author: richardcase

hack/tools/metadata-version-validator/README.md

@@ -0,0 +1,24 @@
+# Metadata Version Validator
+
+## Purpose
+
+A small utility that given a version number it will check that a release series is defined in the passed in metadata.yaml file.
+
+This is primarily for use in release pipelines.
+
+## Usage
+
+First create the binary by:
+
+```bash
+cd hack/tools
+go build -tags=tools -o bin/metadata-version-validator sigs.k8s.io/cluster-api/hack/tools/metadata-version-validator
+```
+
+Then run the binary to check a version:
+
+```bash
+bin/metadata-version-validator --file ../../cluster-api-provider-aws/metadata.yaml --version v2.8.0
+```
+
+If there is no release series defined there will be an error message and also a non-zero exit code.

hack/tools/metadata-version-validator/main.go

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+/*
+Copyright 2025 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.
+*/
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/blang/semver/v4"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/serializer"
+	"k8s.io/klog/v2"
+
+	clusterctlv1 "sigs.k8s.io/cluster-api/cmd/clusterctl/api/v1alpha3"
+)
+
+func main() {
+	file := flag.String("file", "", "Path to metadata.yaml file to check")
+	version := flag.String("version", "metadata.yaml", "The version number to check against the metadata file")
+
+	flag.Parse()
+
+	if *file == "" {
+		klog.Exit("--file must be specified")
+	}
+	if *version == "" {
+		klog.Exit("--version must be specified")
+	}
+
+	if err := runCheckMetadata(*file, *version); err != nil {
+		klog.Exitf("failed checking metadata: %v", err)
+	}
+}
+
+func runCheckMetadata(file, version string) error {
+	versionToCheck := strings.TrimPrefix(version, "v")
+
+	ver, err := semver.Parse(versionToCheck)
+	if err != nil {
+		return fmt.Errorf("failed parsing %s as semver version: %w", version, err)
+	}
+
+	fileData, err := os.ReadFile(file)
+	if err != nil {
+		return fmt.Errorf("failed reading file %s: %w", file, err)
+	}
+
+	scheme := runtime.NewScheme()
+	if err := clusterctlv1.AddToScheme(scheme); err != nil {
+		return fmt.Errorf("failed to add metadata type to scheme: %w", err)
+	}
+	metadata := &clusterctlv1.Metadata{}
+	codecFactory := serializer.NewCodecFactory(scheme)
+
+	if err := runtime.DecodeInto(codecFactory.UniversalDecoder(), fileData, metadata); err != nil {
+		return fmt.Errorf("failed decoding metadata from file: %w", err)
+	}
+
+	for _, series := range metadata.ReleaseSeries {
+		if series.Major == int32(ver.Major) && series.Minor == int32(ver.Minor) {
+			klog.Info("Success, there is a release series defined in the metadata file")
+			return nil
+		}
+	}
+
+	return fmt.Errorf("failed to find release series for version %s in metadata files %s", version, file)
+}