fix(sitemap): publish sitemap.xml alias alongside sitemap index

Author: Clickin

package.json

@@ -8,7 +8,7 @@
     "dev": "astro dev",
     "prebuild": "node scripts/copy-post-assets.mjs",
     "build": "astro build",
-    "postbuild": "pagefind --site dist",
+    "postbuild": "node scripts/postbuild-sitemap-alias.mjs && pagefind --site dist",
     "preview": "astro preview",
     "perf:baseline": "node scripts/perf/lighthouse-baseline.mjs"
   },
@@ -30,4 +30,4 @@
     "sharp": "^0.34.5",
     "typescript": "^5.9.3"
   }
-}
+}

scripts/postbuild-sitemap-alias.mjs

@@ -0,0 +1,35 @@
+import fs from "node:fs";
+import path from "node:path";
+
+const distDir = path.join(process.cwd(), "dist");
+const sitemapIndexPath = path.join(distDir, "sitemap-index.xml");
+const sitemapAliasPath = path.join(distDir, "sitemap.xml");
+
+if (!fs.existsSync(sitemapIndexPath)) {
+  console.log("[sitemap-alias] skipped: sitemap-index.xml was not found.");
+  process.exit(0);
+}
+
+const sitemapIndexXml = fs.readFileSync(sitemapIndexPath, "utf8");
+const locMatches = [...sitemapIndexXml.matchAll(/<loc>([^<]+)<\/loc>/g)];
+const childSitemapLocs = locMatches.map((match) => match[1].trim()).filter(Boolean);
+
+let sourcePath = sitemapIndexPath;
+
+if (childSitemapLocs.length === 1) {
+  try {
+    const childUrl = new URL(childSitemapLocs[0]);
+    const childRelativePath = childUrl.pathname.replace(/^\//, "");
+    const childSitemapPath = path.join(distDir, childRelativePath);
+    if (fs.existsSync(childSitemapPath)) {
+      sourcePath = childSitemapPath;
+    }
+  } catch {
+    console.log(`[sitemap-alias] using index fallback: invalid child sitemap URL (${childSitemapLocs[0]}).`);
+  }
+}
+
+fs.copyFileSync(sourcePath, sitemapAliasPath);
+console.log(
+  `[sitemap-alias] wrote sitemap.xml from ${path.basename(sourcePath)}.`
+);

src/layouts/BaseLayout.astro

@@ -16,7 +16,7 @@ const {
 } = Astro.props;
 const siteUrl = Astro.site ?? Astro.url;
 const baseUrl = new URL(import.meta.env.BASE_URL, siteUrl);
-const sitemapUrl = new URL("sitemap-index.xml", baseUrl).href;
+const sitemapUrl = new URL("sitemap.xml", baseUrl).href;
 const pathWithoutTrailingSlash = Astro.url.pathname.replace(/\/+$/, "") || "/";
 const defaultOgImage = `/og${pathWithoutTrailingSlash === "/" ? "/index" : pathWithoutTrailingSlash}.png`;
 const resolvedOgImage = ogImage ?? defaultOgImage;

src/pages/robots.txt.ts

@@ -1,9 +1,10 @@
 import type { APIRoute } from "astro";
 
-const getRobotsTxt = (sitemapUrl: URL) => `User-agent: *
+const getRobotsTxt = (sitemapUrl: URL, sitemapIndexUrl: URL) => `User-agent: *
 Allow: /
 
 Sitemap: ${sitemapUrl.href}
+Sitemap: ${sitemapIndexUrl.href}
 `;
 
 export const GET: APIRoute = ({ site }) => {
@@ -12,9 +13,10 @@ export const GET: APIRoute = ({ site }) => {
   }
 
   const siteWithBase = new URL(import.meta.env.BASE_URL, site);
-  const sitemapUrl = new URL("sitemap-index.xml", siteWithBase);
+  const sitemapUrl = new URL("sitemap.xml", siteWithBase);
+  const sitemapIndexUrl = new URL("sitemap-index.xml", siteWithBase);
 
-  return new Response(getRobotsTxt(sitemapUrl), {
+  return new Response(getRobotsTxt(sitemapUrl, sitemapIndexUrl), {
     headers: {
       "Content-Type": "text/plain; charset=utf-8",
     },