Add markdownlint CI for blog posts

Author: TineoC

.github/workflows/verify-blog.yml

@@ -0,0 +1,17 @@
+name: Verify blog posts
+on:
+  pull_request:
+    paths:
+      - 'content/*/blog/**/*.md'
+jobs:
+  markdownlint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e
+        with:
+          node-version: '20'
+      - run: npm ci
+      - run: make lint-blogs BASE_REF=${{ github.base_ref }}

.markdownlint.json

@@ -0,0 +1,8 @@
+{
+  "default": true,
+  "MD013": false,
+  "MD033": false,
+  "MD041": false,
+  "MD024": false,
+  "MD046": false
+}

Makefile

@@ -49,7 +49,7 @@ BLOCK_STDOUT_CMD	:= python -c "import os,sys,fcntl; \
 .DEFAULT_GOAL	:= help
 
 .PHONY: targets container-targets
-targets: help gen-content render server clean clean-all production-build preview-build
+targets: help gen-content render server lint-blogs clean clean-all production-build preview-build
 container-targets: container-image container-push container-gen-content container-render container-server
 
 help: ## Show this help text.
@@ -58,6 +58,9 @@ help: ## Show this help text.
 dependencies:
 	npm ci
 
+lint-blogs: ## Run markdownlint on changed blog posts.
+	hack/lint-blogs.sh $(BASE_REF)
+
 gen-content: ## Generates content from external sources.
 	hack/gen-content.sh
 

hack/lint-blogs.sh

@@ -0,0 +1,29 @@
+#!/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 -o errexit
+set -o nounset
+
+BASE_REF="${1:-main}"
+
+CHANGED=$(git diff --name-only "origin/${BASE_REF}...HEAD" -- 'content/*/blog/*.md')
+
+if [ -z "${CHANGED}" ]; then
+  echo "No blog files changed."
+  exit 0
+fi
+
+echo "Linting blog files changed against ${BASE_REF}..."
+echo "${CHANGED}" | xargs markdownlint --config .markdownlint.json