Discourse will now reply with a X-Robots-Tag: noindex header when the requested page isn’t the canonical page for a resource.
While Discourse uses an automatic scrolling design for both topic lists and topics, this isn’t what we show search engine crawlers, like GoogleBot. Search engines see paginated topics, with 20 posts in each page. However, since users can link to specific posts in their own posts and will do so using the /t/title/topic_id/post_id URL format, those will be picked by the crawlers and add duplicated content into your site search results and waste the precious and limited crawl budget your domain have.
To alleviate this issue, our community of users suggested adding the X-Robots-Tag: noindex to URLs like post specific URLs, which we managed to expand to all non-canonical URLs in Discourse. This was released as a hidden site setting and disabled by default 3 months ago, during which we experimented having this header enabled in community sites as well as on meta.discourse.org.
Since results of this period are looking good so far, we just flipped this setting to be in effect by default.
If you for some reason don’t want this behavior on your instance you can still enable indexing of non-canonical pages by running docker exec -i app rails runner "SiteSetting.allow_indexing_non_canonical_urls = true" on your server.
Don’t expect any drastic changes on crawling and search results overnight, but over the next months you should see a decrease of crawls and search results on post specific pages, which will result in more crawl time spent on your site new topics and on content that wasn’t yet indexed because of crawl budget constraints on your domain.
TL;DR: Don’t block non-canonical pages - just point them to a correct url via <link rel="canonical" … > - that’s what it’s made for.
This feature might harm the SEO link-building in the long run:
All deep-links to answers inside topics are on noindex pages now! Does Google like this?
Actually a canonical tag always pointing to the topic url - even for pages deep-linking on an answer - should perfectly do the job – without adding X-Robots-Tag: noindex:
On first crawl of a deep-linking answer page Google recognizes that the page url (answer inside topic) does not fit the canonical-url and then decides to only crawl the canonical-url (topic).
May we add <a rel="nofollow" …> to all links doing this topic-answer deep-linking? Edit: no, see Search engines now blocked from indexing non-canonical pages - #9 by j127
Thereby we might save even more of this precious and limited crawl budget of search engines:
the search engine would neither extract the link in the first place nor do a call to the url. As calling the url results in a response with a X-Robots-Tag: noindex http-header causing the response to be ‘trashed’ by adding the url to the search engines internal ‘noindex’-list.
Some more savings on crawl budget with nofollow added to RSS-feed urls:
I think that the feature shouldn’t be on by default. It’s dangerous from a traffic standpoint, even if it’s only on for a brief time, so anyone who updates now might get an unwelcome surprise.
The canonical tag is the way Google recommends dealing with that problem, and it appears to be working already. Doing weird things with canonical tags can lead to strange problems with Google, and a noindex mistake could be difficult to recover from.
I agree with the first part of your post, but I don’t think internal nofollow is ideal. Internal links help tell search engines which pages on the site are important. Google isn’t going to follow every link it sees, because it knows that it’s seen them before. If they see a URL like example.com/t/1234/5 but have already crawled it and knows that its canonical URL is example.com/t/1234, they probably aren’t going to waste their computing resources visiting the non-canonical version multiple times.
Remove ‘noindex’ for URLs linked to by external websites
Sorry by “answers” I mean “posts” in a topic:
All deep-links from external domains to posts (e.g. forum.example.com/t/example-topic/5/11) have a http-header X-Robots-Tag: noindex now! I suggest to remove this http-header again.
I suggest for <link rel="canonical" … > to never use an URL with a post anchor (the last number in …/t/example-topic/1234/5 ) anywhere. Canonical URLs should always point to the topic url itself (…/t/example-topic/1234 ). I think it is already implemented like this.
Rewrite links for search engines if target url is “redirected” by <link rel="canonical" … >
Very good point, better don’t add rel="nofollow" here.
Discourse has a special view for crawlers. New suggestion for crawler view only:
Convert all internal links pointing to a post-URL (example.com/t/1234/5) to point to the corresponding topic-URL (example.com/t/1234) instead.
Intention: Don’t announce extra URLs to search engines when these extra URLs are “redirected” by <link rel="canonical" … > anyway.
Locations where such links to posts are found:
manually added links in user content
automatically generated links in
first post of topic: “inbound tracked links” from other topics
first post of topic: “selected answer”
first post of topic - topic map open: “topic links”/“liked links”
Excursus: Where does Google find all those URLs?
“inbound tracked links” for search engines
For exactly this reason the automatically generated “inbound tracked links from other topics” on the first post of a topic should also be visible by search engines. Right now these “inbound tracked links” are missing in the crawler view. Edit: They are already in the crawler view.
But pointing to the post-url instead of topic-url (see html source)
<div class="crawler-linkback-list" itemscope="" itemtype="http://schema.org/ItemList">
<div itemprop="itemListElement" itemscope="" itemtype="http://schema.org/ListItem">
<a href="https://meta.discourse.org/t/removing-the-2-3-4-etc-links-for-each-reply-within-a-topic-url/209648/26" itemscope="" itemtype="http://schema.org/DiscussionForumPosting" itemprop="item">
<meta itemprop="url" content="https://meta.discourse.org/t/removing-the-2-3-4-etc-links-for-each-reply-within-a-topic-url/209648/26">
<span itemprop="name">Removing the /2, /3, /4, etc links for each reply within a topic URL</span>
<meta itemprop="position" content="2">
This is a crucial point. It’s one thing to get all of your pages indexed and another to get a relevant ranking for them. In my experience (with big publisher sites), smart internal linking is key to achieve this.
We tested the change in a tech news community over a few months, and we saw a large peak-to-peak increase in anon page views. Our end goal is always to make all Discourse communities healthier in all fronts.
Keep canonical tags always pointing to the topic-url.
– decreasing crawls [A] and considering [C] –
For crawler view only: Convert automatically generated links to always link to topic-url instead of post-url - for all links in first post of topic “inbound tracked links from other topics" and “topic map open: topic link/liked links”.
– decreasing crawls [A] and considering [D], but willfully disregarding [B] –
On [B]: CPU expenses are for crawler-visits only and consist of doing a regex-replace to cut off the last number of internal urls ending in two numbers e.g. …/t/example-topic/1234/5 → …/t/example-topic/1234 in the confined borders of first post of topic “inbound tracked links from other topics” and “topic map open” only.
for all views: add internal nofollow to quotes and manually added links in user content.
– decreasing crawls [A] and considering [B], but slightly disregarding [D] –
On [D]: important links are already automatically duplicated to first topic in "topic map open: topic link/liked links”-section [see 3.] and most quotes stay inside the topic itself anyway.