🌱 Auto-create git tags for the tools/setup-envtest submodule (#3476)

* feat(setup-envtest): Auto-create git tags for the submodule

* chore: inline the action

* address review comments

* bump actions/checkout to be consistent

* fetch tags

Author: porridge

.github/workflows/tag-setup-envtest.yaml

@@ -0,0 +1,25 @@
+name: Tag setup-envtest
+
+on:
+  push:
+    tags:
+      - 'v[0-9]+.[0-9]+.[0-9]+*'
+
+jobs:
+  create-mangled-tag:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write # Required to create a new tag via API
+      
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # tag=v6.0.2
+        with:
+          fetch-tags: true
+
+      - name: Validate and Create Tag
+        id: copy-tag
+        shell: bash
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: ./hack/tag-setup-envtest.sh

hack/tag-setup-envtest.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+
+#  Copyright 2026 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 -euo pipefail
+
+readonly PREFIX="${1:-tools/setup-envtest/}"
+readonly REF="${2:-${GITHUB_REF}}"
+readonly SHA="${3:-${GITHUB_SHA}}"
+readonly REPO="${4:-${GITHUB_REPOSITORY}}"
+
+ORIGINAL_TAG="${REF#refs/tags/}"
+NEW_TAG="${PREFIX}${ORIGINAL_TAG}"
+if git show-ref --verify --quiet "refs/tags/${NEW_TAG}"; then
+  echo "Tag ${NEW_TAG} already exists, nothing to do."
+  exit 0
+fi
+
+echo "Creating new tag: '${NEW_TAG}' at SHA: ${SHA}"
+
+gh api \
+  --method POST \
+  -H "Accept: application/vnd.github+json" \
+  -H "X-GitHub-Api-Version: 2022-11-28" \
+  "/repos/${REPO}/git/refs" \
+  -f ref="refs/tags/${NEW_TAG}" \
+  -f sha="${SHA}"
+echo
+echo "Successfully created ${NEW_TAG}"