From cca78a2264d1a5f139b6eca41a4952bbf2f152c6 Mon Sep 17 00:00:00 2001
From: Valera V Harseko <vharseko@3a-systems.ru>
Date: Wed, 30 Sep 2026 20:54:38 +0300
Subject: [PATCH] Add a custom 404 page

- Add 404.html on the home layout with links to Home, Blog,
  Documentation, Support, GitHub Discussions and the product pages
  (Fixes #235)
- Skip pages with sitemap: false in sitemap.xml
- Render <meta name="robots"> from page.robots, used as noindex on the
  404 page
---
 404.html              | 45 +++++++++++++++++++++++++++++++++++++++++++
 _includes/header.html |  3 +++
 sitemap.xml           |  2 +-
 3 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 404.html

diff --git a/404.html b/404.html
new file mode 100644
index 0000000..e7e5629
--- /dev/null
+++ b/404.html
@@ -0,0 +1,45 @@
+---
+layout: home
+title: Page Not Found
+description: "The page you are looking for does not exist or has moved. Find Open Identity Platform products, documentation, blog articles and community help."
+permalink: /404.html
+sitemap: false
+robots: noindex
+---
+{% comment %}
+  The contents of this file are subject to the terms of the Common Development and
+  Distribution License (the License). You may not use this file except in compliance with the
+  License.
+
+  You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
+  specific language governing permission and limitations under the License.
+
+  When distributing Covered Software, include this CDDL Header Notice in each file and include
+  the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
+  Header, with the fields enclosed by brackets [] replaced by your own identifying
+  information: "Portions copyright [year] [name of copyright owner]".
+
+  Copyright 2026 3A Systems, LLC.
+{% endcomment %}
+<h1>Page Not Found</h1>
+
+<p class="lead">The page you are looking for does not exist or has moved.</p>
+
+<p>If you followed an old link to a blog article or a GitHub wiki page, the article has most likely
+moved to the <a href="/blog/">blog</a>. Otherwise, try one of the pages below.</p>
+
+<h2 class="mt-4">Where to go next</h2>
+<ul>
+  <li><a href="/">Home</a></li>
+  <li><a href="/blog/">Blog</a> &mdash; release notes, how-tos and technical articles</li>
+  <li><a href="https://doc.openidentityplatform.org" target="_blank" rel="noopener">Documentation</a></li>
+  <li><a href="/support">Support</a> &mdash; community help and commercial support</li>
+  <li><a href="https://github.com/orgs/OpenIdentityPlatform/discussions" target="_blank" rel="noopener">GitHub Discussions</a> &mdash; ask the community</li>
+</ul>
+
+<h2 class="mt-4">Products</h2>
+<ul>
+  {%- for product in site.data.products %}
+  <li><a href="{{ product.details_link }}">{{ product.short_description }}</a></li>
+  {%- endfor %}
+</ul>
diff --git a/_includes/header.html b/_includes/header.html
index 5951ac5..b641d47 100644
--- a/_includes/header.html
+++ b/_includes/header.html
@@ -22,6 +22,9 @@
 
 
 <meta name="description" content="{{ page_description }}">
+{%- if page.robots %}
+<meta name="robots" content="{{ page.robots }}">
+{%- endif %}
 <meta name="keywords" content="{{ page.keywords | default: site.keywords }}">
 <meta name="author" content="{{ site.authors }}">
 <meta name="generator" content="Jekyll v{{ jekyll.version }}">
diff --git a/sitemap.xml b/sitemap.xml
index 18f1267..f492f9a 100644
--- a/sitemap.xml
+++ b/sitemap.xml
@@ -26,7 +26,7 @@ layout: null
     </url>
   {% endfor %}
   {% for page in site.pages %}
-    {% if page.layout != null and page.layout != empty and page.layout != "redirect" %}
+    {% if page.layout != null and page.layout != empty and page.layout != "redirect" and page.sitemap != false %}
       <url>
         <loc>{{ site.url }}{{ page.url | remove: "index.html" | remove: ".html" }}</loc>
         {% if page.lastmod %}