runtimeterror/content/posts/using-custom-font-hugo/index.md

title	date	draft	description	featured	toc	comments	categories	tags
Configuring a Custom Font in Hugo	2024-04-23	true	This is a new post about...	false	true	true	Tips	bunny cloudflare hugo meta tailscale

Last week, I came across and immediately fell in love with a delightfully-retro monospace font called Berkeley Mono. I promptly purchased a "personal developer" license and set to work applying the font in my IDE and terminal. I didn't want to stop there, though; the license also permits me to use the font on my personal site, and Berkeley Mono will fit in beautifully with the whole runtimeterror aesthetic.

Long story short, you're looking at a slick new font here. Long story long: I'm about to tell you how I added the font both to the site and to the dynamically-generated OpenGraph share images setup. It wasn't terribly hard to implement, but the Hugo documentation is a bit light on how to do it (and I'm kind of inept at this whole web development thing).

Web Font

The risotto theme for Hugo upon which this site is based defines the default font face(s) as the variable --font-monospace in themes/risotto/static/css/typography.css, and then that variable is inserted wherever the font may need to be set:

/* torchlight! {"lineNumbers":true} */
/* Fonts */
:root {
    --font-monospace: "Fira Mono", monospace; /* [tl! **] */
}

body {
    font-family: var(--font-monospace); /* [tl! **] */
    font-size: 16px;
    line-height: 1.5rem;
}

This makes it easy to override the theme's font by referencing my preferred font in static/custom.css:

/* font overrides */
:root {
  --font-monospace: 'Berkeley Mono', 'Fira Mono', monospace; /* [tl! **] */
}

And that would be the end of things if I could expect that everyone who visited my site already had the Berkeley Mono font installed; if they don't, though, the site will fallback to either the Fira Mono font or whatever generic monospace font is on the system. So maybe I'll add a few other monospace fonts just for good measure:

/* font overrides */
:root {
  --font-monospace: 'Berkeley Mono', 'IBM Plex Mono', 'Cascadia Mono', 'Roboto Mono', 'Source Code Pro', 'Fira Mono', 'Courier New', monospace; /* [tl! **] */
}

That gives me a few more fallback fonts to fall back to if my preferred font isn't available. But let's see about making that font available.

Hosted Locally

I can use a @font-face rule to tell the browser how to find the .woff2/.woff files for my preferred web font, and I could just set the src: url parameter to point to a local path in my Hugo environment:

/* load preferred font */
@font-face {
  font-family: 'Berkeley Mono';
  font-style: normal;
  font-weight: 400;
  src: local('Berkeley Mono'),
    url('/fonts/BerkeleyMono.woff2') format('woff2'),
    url('/fonts/BerkeleyMono.woff') format('woff')
}

And that would work just fine... but it would require storing those web font files in the GitHub repo which powers my site, and I'd rather not host any paid font files in such a way.

So instead, I opted to store the web font files in a CDN, where I could exercise some degree of access control, learn more about a web technology I haven't played with a whole lot, and make use of a cool cdn.runtimeterror.dev subdomain in the process.

{{% notice note "Double the CDN, double the fun" %}} Of course, while writing this post I gave in to my impulsive nature and migrated the site from Cloudflare to Bunny.net. So I'm going to briefly describe how I set this up first on Cloudflare R2 and later on Bunny Storage. {{% /notice %}}

Cloudflare R2

Getting started with R2 was really easy; I just created a new R2 bucket called runtimeterror and connected it to the custom domain cdn.runtimeterror.dev. I put the two web font files in a folder titled fonts and uploaded them to the bucket so that they can be accessed under https://cdn.runtimeterror.dev/fonts/.

I could then employ a Cross-Origin Resource Sharing (CORS) policy to ensure the fonts hosted on my fledgling CDN can only be loaded on my site. I configured the policy to also allow access from my localhost Hugo build environment as well as a preview Neocities environment I use for testing such major changes:

[
  {
    "AllowedOrigins": [
      "http://localhost:1313",
      "https://secret--runtimeterror--preview.neocities.org",
      "https://runtimeterror.dev"
    ],
    "AllowedMethods": [
      "GET"
    ]
  }
]

Then I just needed to update the @font-face rule accordingly:

/* load preferred font */
@font-face {
  font-family: 'Berkeley Mono';
  font-style: normal;
  font-weight: 400;
  font-display: fallback; /* [tl! ++] */
  src: local('Berkeley Mono'),
    url('/fonts/BerkeleyMono.woff2') format('woff2'), /* [tl! --] */
    url('https://cdn.runtimeterror.dev/fonts/BerkeleyMono.woff2') format('woff2'), /* [tl! ++] */
    url('/fonts/BerkeleyMono.woff') format('woff') /* [tl! --] */
    url('https://cdn.runtimeterror.dev/fonts/BerkeleyMono.woff') format('woff') /* [tl! ++] */
}

I added in the font-display: fallback; descriptor to address the fact that the site will now be loading a remote font. Rather than blocking and not rendering text until the preferred font is loaded, it will show text in one of the available fallback fonts. If the preferred font loads quickly enough, it will be swapped in; otherwise, it will just show up on the next page load. I figured this was a good middle-ground between wanting the site to load quickly while also looking the way I want it to.

To test my work, I ran hugo server to build and serve the site locally on http://localhost:1313... and promptly encountered a cascade of CORS-related errors. I kept tweaking the policy and trying to learn more about what I'm doing (reminder: I'm bad at this), but just couldn't figure out what was preventing the font from being loaded.

I eventually discovered that sometimes you need to clear Cloudflare's cache so that new policy changes will take immediate effect. Once I purged everything, the errors went away and the font loaded successfully.

Bunny Storage

After migrating my domain to Bunny.net, the CDN font setup was pretty similar - but also different enough that it's worth mentioning. I started by creating a new Storage Zone named runtimeterror-storage, and selecting an appropriate-seeming set of replication regions. I then uploaded the same fonts/ folder as before.

To be able to access the files in Bunny Storage, I then connected a new Pull Zone (called runtimeterror-pull) and linked that Pull Zone with the cdn.runtimeterror.dev hostname. I also made sure to enable the option to automatically generate a certificate for this host.

Rather than needing me to understand CORS and craft a viable policy file, Bunny provides a clean UI with easy-to-understand options for configuring the pull zone security. I enabled the options to block root path access, block POST requests, and block direct file access, and also added the same trusted referrers as before:

I made sure to use the same paths as I had on Cloudflare so I didn't need to update the Hugo config at all even after changing CDNs. That same CSS from before still works:

/* load preferred font */
@font-face {
  font-family: 'Berkeley Mono';
  font-style: normal;
  font-weight: 400;
  font-display: fallback;
  src: local('Berkeley Mono'),
    url('https://cdn.runtimeterror.dev/fonts/BerkeleyMono.woff2') format('woff2'),
    url('https://cdn.runtimeterror.dev/fonts/BerkeleyMono.woff') format('woff')
}

So that's the web font for the web site sorted; now let's tackle the font in the dynamically-generated OpenGraph share images.

OpenGraph Image Filter Text

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