Builds feed URL from site URL to reduce replication

_data/metadata.json

@@ -6,7 +6,6 @@
     "subtitle": "I am writing about my experiences as a naval navel-gazer.",
     "filename": "feed.xml",
     "path": "/feed/feed.xml",
-    "url": "https://myurl.com/feed/feed.xml",
     "id": "https://myurl.com/"
   },
   "author": {

feed/feed.njk

@@ -6,7 +6,8 @@ eleventyExcludeFromCollections: true
 <feed xmlns="http://www.w3.org/2005/Atom">
 	<title>{{ metadata.title }}</title>
 	<subtitle>{{ metadata.feed.subtitle }}</subtitle>
-	<link href="{{ metadata.feed.url }}" rel="self"/>
+	{% set absoluteUrl %}{{ metadata.feed.path | url | absoluteUrl(metadata.url) }}{% endset %}
+	<link href="{{ absoluteUrl }}" rel="self"/>
 	<link href="{{ metadata.url }}"/>
 	<updated>{{ collections.posts | rssLastUpdatedDate }}</updated>
 	<id>{{ metadata.feed.id }}</id>