feat(blog): external canonical for syndicated posts (nodejs#7879)

* feat(blog): external canonical for syndicated posts

* docs(frontmatter): external canonical for syndicated posts

* docs(frontmatter): clarify syndicated context

Signed-off-by: Matt Cowley <[email protected]>

---------

Signed-off-by: Matt Cowley <[email protected]>

Author: MattIPv4

apps/site/next.dynamic.mjs

@@ -230,7 +230,8 @@ const getDynamicRouter = async () => {
     ];
 
     // Default canonical URL for the page
-    pageMetadata.alternates.canonical = getUrlForPathname(locale, path);
+    pageMetadata.alternates.canonical =
+      data.canonical ?? getUrlForPathname(locale, path);
 
     // Default alternate URL for the page in the default locale
     pageMetadata.alternates.languages['x-default'] = getUrlForPathname(

apps/site/pages/en/blog/announcements/mikeal.md

@@ -4,6 +4,7 @@ category: announcements
 title: 'In Memory of Mikeal Rogers: A Builder of Communities'
 layout: blog-post
 author: Robin Bender Ginn
+canonical: https://openjsf.org/blog/in-memory-of-mikeal-rogers
 ---
 
 ![][mikeal-rogers-image]

docs/adding-pages.md

@@ -63,6 +63,10 @@ The frontmatter (YAML block at the top) configures page metadata:
 - `description`: Optional meta description for SEO
 - `authors`: For learn pages, list of GitHub usernames
 
+In cases where content has been syndicated from another source, you should also include:
+
+- `canonical`: The original URL of the content
+
 ### 3. Choose the Appropriate Layout
 
 Available layouts are defined in `apps/site/layouts/`, and mapped in `components/withLayout`.