>>> [!note] Migrated issue <!-- Drupal.org comment --> <!-- Migrated from issue #1245660. --> Reported by: [jwilson3](https://www.drupal.org/user/220177) >>> <p>There is a very old request for the Domain Access module to support Canonical URLs to improve SEO: <span class="drupalorg-gitlab-issue-link project-issue-status-info project-issue-status-5"><a href="https://www.drupal.org/project/domain/issues/414882" title="Status: Closed (won't fix)">#414882: Include Canonical URL tag in links extra-domains</a></span>.</p> <p>To explain the background, the basic issue is that when you install Domain Access, essentially *ALL* Drupal requests -- be them node pages, views, taxonomy term pages, error pages, or literally ANYTHING -- could be considered duplicate content from the primary domain by search engines. Often the case is that the entire page is exactly the same, but the layout (eg block positions) and style (theme) are different. This presents a serious problem for people that use the Domain Access module, that they may not be aware of.</p> <p>One would think you can get around this problem through proper configuration of Domain Access, and certainly you can prevent duplication of node content, by ensuring that nodes are never 'sent to all affiliates' and that only one piece of content is visible from each domain. However this is only one of many possible use-cases that Domain Access enables. What about content that is sent to all affiliates, or content that is sent to two affiliates, but specifically not to be seen on the primary domain.</p> <p>The problem is exacerbated by the fact that ANY PAGE REQUEST from subdomains that is NOT a node, is a copy of the same page from the primary domain. Modules that provide specific pages like Ubercarts /cart url, or Contact modules /contact URL, are (without further customization) available at all the domains. There should be an easy way to ensure users are not penalized for these types of configurations.</p> <p>Sadly, the conclusion on <span class="drupalorg-gitlab-issue-link project-issue-status-info project-issue-status-5"><a href="https://www.drupal.org/project/domain/issues/414882" title="Status: Closed (won't fix)">#414882: Include Canonical URL tag in links extra-domains</a></span> was that this functionality is something for a sub-module to handle, not Domain Access directly. Furthermore, since NodeWords is built to handle Canonical URLs and this module is the bridge between Nodewords and Domain Access, I present a proposal to make this module the key for Canonical URLs support for Domain Access.</p> <p>I've written a working proof of concept that adds Canonical URL support to domain_meta, by hooking into hook_nodewords_tag_alter. There are currently two specific cases supported:</p> <ul> <li>Nodes that distribute content to multiple domains, should have a canonical url that points to the primary domain.</li> <li>All non-node pages on the non-primary domain should have a canonical url that points to the primary domain.</li> </ul> <p>There may be more special cases (eg taxonomy and users) however the current client's needs did not demand a solution for this at the moment, so they are relegated to the second rule above for non-node pages.</p> <p>There are a few changes in the NodeWords queue that may have an effect on how the canonical urls work going forward so we need to keep an eye on <span class="drupalorg-gitlab-issue-link project-issue-status-info project-issue-status-7"><a href="https://www.drupal.org/project/nodewords/issues/1244132" title="Status: Closed (fixed)">#1244132: Change Canonical URL handling with option to use the url_alias, full path</a></span>.</p> <p>Otherwise, the patch in the first comment is a great starting point, and has been heavily tested already by myself. </p>