From 8580fb5e42f3cc0b11fd20241f0e53a8a2ccbcbf Mon Sep 17 00:00:00 2001
From: Peter Bengtsson <mail@peterbe.com>
Date: Fri, 13 May 2022 10:46:57 -0400
Subject: [PATCH 1/2] fast HEAD requests (#27672)

* fast HEAD requests

* update test
---
 middleware/fast-head.js   | 16 ++++++++++++++++
 middleware/index.js       |  5 +++++
 tests/rendering/server.js |  7 ++++++-
 3 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 middleware/fast-head.js

diff --git a/middleware/fast-head.js b/middleware/fast-head.js
new file mode 100644
index 0000000000..b39676a808
--- /dev/null
+++ b/middleware/fast-head.js
@@ -0,0 +1,16 @@
+import { cacheControlFactory } from './cache-control.js'
+
+const cacheControl = cacheControlFactory(60 * 60 * 24)
+
+export default function fastHead(req, res, next) {
+  const { context } = req
+  const { page } = context
+  if (page) {
+    // Since the *presence* is not affected by the request, we can cache
+    // this and allow the CDN to hold on to it.
+    cacheControl(res)
+
+    return res.status(200).send('')
+  }
+  next()
+}
diff --git a/middleware/index.js b/middleware/index.js
index 6aa26dc383..16f30a7011 100644
--- a/middleware/index.js
+++ b/middleware/index.js
@@ -65,6 +65,7 @@ import archivedAssetRedirects from './archived-asset-redirects.js'
 import favicons from './favicons.js'
 import setStaticAssetCaching from './static-asset-caching.js'
 import protect from './overload-protection.js'
+import fastHead from './fast-head.js'
 
 const { DEPLOYMENT_ENV, NODE_ENV } = process.env
 const isDevelopment = NODE_ENV === 'development'
@@ -309,6 +310,10 @@ export default function (app) {
   // Check for a dropped connection before proceeding (again)
   app.use(haltOnDroppedConnection)
 
+  // Specifically deal with HEAD requests before doing the slower
+  // full page rendering.
+  app.head('/*', fastHead)
+
   // *** Preparation for render-page: contextualizers ***
   app.use(asyncMiddleware(instrument(releaseNotes, './contextualizers/release-notes')))
   app.use(instrument(graphQL, './contextualizers/graphql'))
diff --git a/tests/rendering/server.js b/tests/rendering/server.js
index 22a5dbc977..aab3c7f5e6 100644
--- a/tests/rendering/server.js
+++ b/tests/rendering/server.js
@@ -29,8 +29,13 @@ describe('server', () => {
   test('supports HEAD requests', async () => {
     const res = await head('/en')
     expect(res.statusCode).toBe(200)
-    expect(res.headers).not.toHaveProperty('content-length')
+    expect(res.headers['content-length']).toBe('0')
     expect(res.text).toBe('')
+    // Because the HEAD requests can't be different no matter what's
+    // in the request headers (Accept-Language or Cookies)
+    // it's safe to let it cache. The only key is the URL.
+    expect(res.headers['cache-control']).toContain('public')
+    expect(res.headers['cache-control']).toMatch(/max-age=\d+/)
   })
 
   test('renders the homepage', async () => {

From 1108ecda90ef8a30a8e04b2fce5125bf57f7c80a Mon Sep 17 00:00:00 2001
From: Peter Bengtsson <mail@peterbe.com>
Date: Fri, 13 May 2022 11:16:19 -0400
Subject: [PATCH 2/2] remove loader.io middleware (#27678)

---
 middleware/index.js                 | 2 --
 middleware/loaderio-verification.js | 6 ------
 2 files changed, 8 deletions(-)
 delete mode 100644 middleware/loaderio-verification.js

diff --git a/middleware/index.js b/middleware/index.js
index 16f30a7011..5ede4d9bd4 100644
--- a/middleware/index.js
+++ b/middleware/index.js
@@ -44,7 +44,6 @@ import archivedEnterpriseVersions from './archived-enterprise-versions.js'
 import robots from './robots.js'
 import earlyAccessLinks from './contextualizers/early-access-links.js'
 import categoriesForSupport from './categories-for-support.js'
-import loaderio from './loaderio-verification.js'
 import triggerError from './trigger-error.js'
 import releaseNotes from './contextualizers/release-notes.js'
 import whatsNewChangelog from './contextualizers/whats-new-changelog.js'
@@ -304,7 +303,6 @@ export default function (app) {
     '/categories.json',
     asyncMiddleware(instrument(categoriesForSupport, './categories-for-support'))
   )
-  app.use(instrument(loaderio, './loaderio-verification'))
   app.get('/_500', asyncMiddleware(instrument(triggerError, './trigger-error')))
 
   // Check for a dropped connection before proceeding (again)
diff --git a/middleware/loaderio-verification.js b/middleware/loaderio-verification.js
deleted file mode 100644
index 346f612fe2..0000000000
--- a/middleware/loaderio-verification.js
+++ /dev/null
@@ -1,6 +0,0 @@
-// prove to loader.io that we own this site
-// by responding to requests like `/loaderio-12345/` with `loaderio-12345`
-export default function loaderIoVerification(req, res, next) {
-  if (!req.path.startsWith('/loaderio-')) return next()
-  return res.send(req.path.replace(/\//g, ''))
-}