Adding OpenGraph previews to Jekyll

I’m on a tear adding support for open web standards to my website(s) - if I’ve missed one, let me know. I’ve just added RSS meta tags which allow for feed reading plugins to suggest the RSS feed - rather than people having to find the RSS link (it’s at the bottom of the page) and paste that into their feed reader. There must be dozens of people who haven’t been reading my amazing content because it was too hard to add my site into their feed reader.

The other standard is OpenGraph which tells other services how to build a rich preview of your site. The obvious examples are links from social media sites (like Facebook, the author of the standard), or messaging apps:

a screenshot of an message showing a link to one of my blog posts, with a title and preview image

This is fairly simple to do, you just need to add some <meta> tags to the <head> of your site, for example my Jekyll template:

<meta property="og:url" content="{{ page.url | absolute_url }}">
<meta property="og:type" content="{% if page.type != null %}{{ page.type }}{% elsif page.layout == "post" %}article{% else %}website{% endif %}">
<meta property="og:title" content="{{ page.title }}">
<meta property="og:description" content="{{ site.description }}">
<meta property="og:image" content="{% if page.image != null %}{{ page.image }}{% else %}/images/me.jpg{% endif %}">

This will populate the correct URL (the absolute URL for the current page), guess the type either from a field on the page or whether it’s a post, and show a default image of me or a custom one specified by the page. This lets me customise posts with frontmatter:

title: "A custom OpenGraph post"
type: article
layout: post
image: /images/some-image.jpeg
# ... content of the post

I then checked using that my formatting was correct. As with most standards, different implementations with have varying quirks and may display things differently. Since I’m just adding a preview image, I’m not too fussed about 100% correctness.

This has also been done to my photos website so if a particular post is shared from there, it will get the preview thumbnail.

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