Extend custom CSS cache time with digest paths (#33207)

app/controllers/custom_css_controller.rb

@@ -2,7 +2,7 @@
 
 class CustomCssController < ActionController::Base # rubocop:disable Rails/ApplicationController
   def show
-    expires_in 3.minutes, public: true
+    expires_in 1.month, public: true
     render content_type: 'text/css'
   end
 

app/helpers/theme_helper.rb

@@ -23,8 +23,31 @@ module ThemeHelper
     end
   end
 
+  def custom_stylesheet
+    if active_custom_stylesheet.present?
+      stylesheet_link_tag(
+        custom_css_path(active_custom_stylesheet),
+        host: root_url,
+        media: :all,
+        skip_pipeline: true
+      )
+    end
+  end
+
   private
 
+  def active_custom_stylesheet
+    if cached_custom_css_digest.present?
+      [:custom, cached_custom_css_digest.to_s.first(8)]
+        .compact_blank
+        .join('-')
+    end
+  end
+
+  def cached_custom_css_digest
+    Rails.cache.read(:setting_digest_custom_css)
+  end
+
   def theme_color_for(theme)
     theme == 'mastodon-light' ? Themes::THEME_COLORS[:light] : Themes::THEME_COLORS[:dark]
   end

app/models/form/admin_settings.rb

@@ -69,6 +69,10 @@ class Form::AdminSettings
     favicon
   ).freeze
 
+  DIGEST_KEYS = %i(
+    custom_css
+  ).freeze
+
   OVERRIDEN_SETTINGS = {
     authorized_fetch: :authorized_fetch_mode?,
   }.freeze
@@ -122,6 +126,8 @@ class Form::AdminSettings
     KEYS.each do |key|
       next unless instance_variable_defined?(:"@#{key}")
 
+      cache_digest_value(key) if DIGEST_KEYS.include?(key)
+
       if UPLOAD_KEYS.include?(key)
         public_send(key).save
       else
@@ -133,6 +139,18 @@ class Form::AdminSettings
 
   private
 
+  def cache_digest_value(key)
+    Rails.cache.delete(:"setting_digest_#{key}")
+
+    key_value = instance_variable_get(:"@#{key}")
+    if key_value.present?
+      Rails.cache.write(
+        :"setting_digest_#{key}",
+        Digest::SHA256.hexdigest(key_value)
+      )
+    end
+  end
+
   def typecast_value(key, value)
     if BOOLEAN_KEYS.include?(key)
       value == '1'

app/views/layouts/application.html.haml

@@ -34,7 +34,7 @@
     = csrf_meta_tags unless skip_csrf_meta_tags?
     %meta{ name: 'style-nonce', content: request.content_security_policy_nonce }
 
-    = stylesheet_link_tag custom_css_path, skip_pipeline: true, host: root_url, media: 'all'
+    = custom_stylesheet
 
     = yield :header_tags