Branch was updated using the 'autoupdate branch' Actions workflow.

middleware/archived-enterprise-versions-assets.js

@@ -3,6 +3,8 @@ const patterns = require('../lib/patterns')
 const isArchivedVersion = require('../lib/is-archived-version')
 const got = require('got')
 
+const ONE_DAY = 24 * 60 * 60 // 1 day in seconds
+
 // This module handles requests for the CSS and JS assets for
 // deprecated GitHub Enterprise versions by routing them to static content in
 // help-docs-archived-enterprise-versions
@@ -26,8 +28,10 @@ module.exports = async (req, res, next) => {
     res.set('content-length', r.headers['content-length'])
     res.set('x-is-archived', 'true')
     res.set('x-robots-tag', 'noindex')
-    res.send(r.body)
+    // Allow the browser and Fastly to cache these
+    res.set('cache-control', `public, max-age=${ONE_DAY}`)
+    return res.send(r.body)
   } catch (err) {
-    next()
+    return next()
   }
 }

middleware/archived-enterprise-versions.js

@@ -46,7 +46,7 @@ module.exports = async (req, res, next) => {
       res.set('location', staticRedirect[1])
     }
 
-    res.send(r.body)
+    return res.send(r.body)
   } catch (err) {
     for (const fallbackRedirect of getFallbackRedirects(req, requestedVersion) || []) {
       try {
@@ -54,7 +54,7 @@ module.exports = async (req, res, next) => {
         return res.redirect(301, fallbackRedirect)
       } catch (err) { } // noop
     }
-    next()
+    return next()
   }
 }
 

middleware/disable-caching-on-safari.js

@@ -3,5 +3,5 @@ module.exports = (req, res, next) => {
   if (isSafari) {
     res.header('Last-Modified', (new Date()).toUTCString())
   }
-  next()
+  return next()
 }

middleware/index.js

@@ -37,8 +37,10 @@ module.exports = function (app) {
   app.use(require('./handle-csrf-errors')) // Must come before regular handle-errors
 
   // *** Headers ***
+  app.set('etag', false) // We will manage our own ETags if desired
   app.use(require('compression')())
   app.use(require('./disable-caching-on-safari'))
+  app.use(require('./set-fastly-surrogate-key'))
 
   // *** Config and context for redirects ***
   app.use(require('./req-utils')) // Must come before record-redirect and events
@@ -66,10 +68,20 @@ module.exports = function (app) {
     etag: false,
     immutable: true,
     lastModified: false,
-    maxAge: '28 days'
+    maxAge: '28 days' // Could be infinite given our fingerprinting
+  }))
+  app.use('/assets', express.static('assets', {
+    index: false,
+    etag: false,
+    lastModified: false,
+    maxAge: '1 day' // Relatively short in case we update images
+  }))
+  app.use('/public', express.static('data/graphql', {
+    index: false,
+    etag: false,
+    lastModified: false,
+    maxAge: '7 days' // A bit longer since releases are more sparse
   }))
-  app.use('/assets', express.static('assets'))
-  app.use('/public', express.static('data/graphql'))
   app.use('/events', instrument('./events'))
   app.use('/csrf', instrument('./csrf-route'))
   app.use('/search', instrument('./search'))

middleware/render-page.js

@@ -115,6 +115,7 @@ module.exports = async function renderPage (req, res, next) {
   const output = await liquid.parseAndRender(layout, context)
 
   // First, send the response so the user isn't waiting
+  // NOTE: Do NOT `return` here as we still need to cache the response afterward!
   res.send(output)
 
   // Finally, save output to cache for the next time around

middleware/set-fastly-surrogate-key.js

@@ -0,0 +1,12 @@
+module.exports = (req, res, next) => {
+  // Fastly provides a Soft Purge feature that allows you to mark content as outdated (stale) instead of permanently
+  // purging and thereby deleting it from Fastly's caches. Objects invalidated with Soft Purge will be treated as
+  // outdated (stale) while Fastly fetches a new version from origin.
+  //
+  // Use of a surrogate key is required for soft purging
+  // https://docs.fastly.com/en/guides/soft-purges
+  // https://docs.fastly.com/en/guides/getting-started-with-surrogate-keys
+  res.set('surrogate-key', 'all-the-things')
+
+  return next()
+}

tests/rendering/server.js

@@ -66,7 +66,7 @@ describe('server', () => {
     const res = await get('/en')
     expect(res.headers['cache-control']).toBe('private, no-store')
     expect(res.headers['surrogate-control']).toBe('private, no-store')
-    expect(res.headers).not.toHaveProperty('surrogate-key')
+    expect(res.headers['surrogate-key']).toBe('all-the-things')
   })
 
   test('does not render duplicate <html> or <body> tags', async () => {