FIX: on 404 from brotli asset path return a correctly encoded doc

old implementation would cache the 404 for 1 year with incorrect encoding

hilarity would ensue

app/controllers/static_controller.rb

@@ -135,23 +135,25 @@ class StaticController < ApplicationController
     opts = { disposition: nil }
     opts[:type] = "application/javascript" if path =~ /\.js.br$/
 
-    response.headers["Expires"] = 1.year.from_now.httpdate
-    response.headers["Cache-Control"] = 'max-age=31557600, public'
-    response.headers["Content-Encoding"] = 'br'
     begin
       response.headers["Last-Modified"] = File.ctime(path).httpdate
       response.headers["Content-Length"] = File.size(path).to_s
     rescue Errno::ENOENT
-      raise Discourse::NotFound
+      response.headers["Expires"] = 5.seconds.from_now.httpdate
+      response.headers["Cache-Control"] = 'max-age=5, public'
+      expires_in 5.seconds, public: true, must_revalidate: false
+
+      render text: "missing brotli asset", status: 404
+      return
     end
 
+    response.headers["Expires"] = 1.year.from_now.httpdate
+    response.headers["Cache-Control"] = 'max-age=31557600, public'
+    response.headers["Content-Encoding"] = 'br'
+
     expires_in 1.year, public: true, must_revalidate: false
 
-    if File.exists?(path)
     send_file(path, opts)
-    else
-      raise Discourse::NotFound
-    end
   end
 
 

spec/controllers/static_controller_spec.rb

@@ -3,6 +3,15 @@ require 'rails_helper'
 describe StaticController do
 
   context 'brotli_asset' do
+    it 'returns a brotli encoded 404 if asset is missing' do
+
+        get :brotli_asset, path: 'missing.js'
+
+        expect(response.status).to eq(404)
+        expect(response.headers['Content-Encoding']).not_to eq('br')
+        expect(response.headers["Cache-Control"]).to match(/max-age=5/)
+    end
+
     it 'has correct headers for brotli assets' do
       begin
         assets_path = Rails.root.join("public/assets")