tplimpl: Add translation links to the default sitemap template

For pages with translations, add links with hreflang attributes to the
default sitemap template. This helps Google to show the correct
language page in its search results. The syntax used is based on
Google's example at [1].

Also update the sitemap template docs to reflect the changes in the
default template.

[1]
https://support.google.com/webmasters/answer/2620865?hl=en&topic=2370587&ctx=topic

Fixes #2569

diff --git a/docs/content/templates/sitemap.md b/docs/content/templates/sitemap.md
index 1ecbfb3bef176b089f30dcfb7da9257207442a87..c893f3155419f54c39a4c89c72165e3856210a0e 100644 (file)
--- a/docs/content/templates/sitemap.md
+++ b/docs/content/templates/sitemap.md
@@ -31,16 +31,29 @@ one.
 
 ## Hugo’s sitemap.xml
 
-This template respects the version 0.9 of the [Sitemap
-Protocol](http://www.sitemaps.org/protocol.html).
+This template uses the version 0.9 of the [Sitemap
+Protocol](http://www.sitemaps.org/protocol.html) with Google's [hreflang
+attributes](https://support.google.com/webmasters/answer/2620865?hl=en&topic=2370587&ctx=topic)
+for linking to translated content.
 
-    <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+    <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
+      xmlns:xhtml="http://www.w3.org/1999/xhtml">
       {{ range .Data.Pages }}
       <url>
         <loc>{{ .Permalink }}</loc>{{ if not .Lastmod.IsZero }}
         <lastmod>{{ safeHTML ( .Lastmod.Format "2006-01-02T15:04:05-07:00" ) }}</lastmod>{{ end }}{{ with .Sitemap.ChangeFreq }}
         <changefreq>{{ . }}</changefreq>{{ end }}{{ if ge .Sitemap.Priority 0.0 }}
-        <priority>{{ .Sitemap.Priority }}</priority>{{ end }}
+        <priority>{{ .Sitemap.Priority }}</priority>{{ end }}{{ if .IsTranslated }}{{ range .Translations }}
+        <xhtml:link
+                    rel="alternate"
+                    hreflang="{{ .Lang }}"
+                    href="{{ .Permalink }}"
+                    />{{ end }}
+        <xhtml:link
+                    rel="alternate"
+                    hreflang="{{ .Lang }}"
+                    href="{{ .Permalink }}"
+                    />{{ end }}
       </url>
       {{ end }}
     </urlset>

diff --git a/tpl/tplimpl/template_embedded.go b/tpl/tplimpl/template_embedded.go
index 2d4769f788922d9739ecb5ca1cefd50f04381302..c02e6569a523b7fa84ce9c6d4d0370fb897a11f5 100644 (file)
--- a/tpl/tplimpl/template_embedded.go
+++ b/tpl/tplimpl/template_embedded.go
@@ -87,13 +87,24 @@ func (t *templateHandler) embedTemplates() {
   </channel>
 </rss>`)
 
-       t.addInternalTemplate("_default", "sitemap.xml", `<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+       t.addInternalTemplate("_default", "sitemap.xml", `<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
+  xmlns:xhtml="http://www.w3.org/1999/xhtml">
   {{ range .Data.Pages }}
   <url>
     <loc>{{ .Permalink }}</loc>{{ if not .Lastmod.IsZero }}
     <lastmod>{{ safeHTML ( .Lastmod.Format "2006-01-02T15:04:05-07:00" ) }}</lastmod>{{ end }}{{ with .Sitemap.ChangeFreq }}
     <changefreq>{{ . }}</changefreq>{{ end }}{{ if ge .Sitemap.Priority 0.0 }}
-    <priority>{{ .Sitemap.Priority }}</priority>{{ end }}
+    <priority>{{ .Sitemap.Priority }}</priority>{{ end }}{{ if .IsTranslated }}{{ range .Translations }}
+    <xhtml:link
+                rel="alternate"
+                hreflang="{{ .Lang }}"
+                href="{{ .Permalink }}"
+                />{{ end }}
+    <xhtml:link
+                rel="alternate"
+                hreflang="{{ .Lang }}"
+                href="{{ .Permalink }}"
+                />{{ end }}
   </url>
   {{ end }}
 </urlset>`)