From 447a2e160014c7fd74b404800185bfedd7597540 Mon Sep 17 00:00:00 2001
From: Rohan Kumar <seirdy@seirdy.one>
Date: Thu, 28 Mar 2024 00:16:48 -0400
Subject: [PATCH] New note: short cache busting fingerprints

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+---
+title: "Short cache busting fingerprints in Hugo"
+date: 2024-03-28T00:16:48-04:00
+replyURI: "https://github.com/gohugoio/hugo/issues/6241"
+replyTitle: "Shorter fingerprinting (Hugo issue 6241)"
+replyType: "DiscussionForumPosting"
+replyAuthor: "XhmikosR"
+replyAuthorURI: "https://github.com/XhmikosR"
+---
+
+I use a quick `crypto.FNV32a`-based fix for short cache-busting fingerprints that doesn't directly rely on the unstable `.Key` method.
+
+{{<codefigure>}}{{<codecaption lang="Go template">}}
+
+I use Hugo's `crypto.FNV32a` to generate a short hash, then copy the resource to a new path with that fingerprint.
+
+{{</codecaption>}}
+
+```figure
+{{ $resource := resources.Get . -}}
+{{- $target_path_formatStr := (replaceRE `(\.[^\.]*)$` ".%d$1" .) -}}
+{{- $cacheBuster := $resource.Content | crypto.FNV32a -}}
+{{- $target_path := printf $target_path_formatStr $cacheBuster -}}
+{{- return resources.Copy $target_path $resource -}}
+```
+
+{{</codefigure>}}
+
+{{<codefigure>}}{{<codecaption lang="Go template">}}
+
+You can [see it used in my site's <code>head</code> element](https://git.sr.ht/~seirdy/seirdy.one/blob/master/layouts/partials/head.html). I invoke it using `partialCached` so the fingerprinting only happens once per resource:
+
+{{</codecaption>}}
+
+```figure
+{{ $icon_svg := partialCached "cache-bust.html" "/favicon.svg" "/favicon.svg" }}
+{{- printf `<link rel="icon" sizes="any" href="%s" type="image/svg+xml" />` $icon_svg.RelPermalink | safeHTML }}
+```
+
+{{</codefigure>}}
+
+{{<codefigure>}}{{<codecaption lang="HTML">}}
+
+Here's a snippet of the final rendered result:
+
+{{</codecaption>}}
+
+```figure
+<link rel="icon" sizes="any" href="/favicon.2229316949.svg" type="image/svg+xml"/>
+```
+
+{{</codefigure>}}
+
+Encoding it to a higher base and using alphanumerics could shave off 1-2&nbsp;ch.