cache asset images more aggressively (#23553)

* cache asset images more aggressively

* more careful about which gets the manual surrogate key

* fix rendered-content-link-checker script too

* feedbacked

middleware/index.js

@@ -14,7 +14,10 @@ import csrf from './csrf.js'
 import handleCsrfErrors from './handle-csrf-errors.js'
 import compression from 'compression'
 import disableCachingOnSafari from './disable-caching-on-safari.js'
-import setDefaultFastlySurrogateKey from './set-fastly-surrogate-key.js'
+import {
+  setDefaultFastlySurrogateKey,
+  setManualFastlySurrogateKey,
+} from './set-fastly-surrogate-key.js'
 import setFastlyCacheHeaders from './set-fastly-cache-headers.js'
 import catchBadAcceptLanguage from './catch-bad-accept-language.js'
 import reqUtils from './req-utils.js'
@@ -57,6 +60,7 @@ import featuredLinks from './featured-links.js'
 import learningTrack from './learning-track.js'
 import next from './next.js'
 import renderPage from './render-page.js'
+import assetPreprocessing from './asset-preprocessing.js'
 
 const { NODE_ENV } = process.env
 const isDevelopment = NODE_ENV === 'development'
@@ -95,17 +99,25 @@ export default function (app) {
       instrument(archivedEnterpriseVersionsAssets, './archived-enterprise-versions-assets')
     )
   )
+  // This must come before the express.static('assets') middleware.
+  app.use(assetPreprocessing)
+  // By specifying '/assets/cb-' and not just '/assets/' we
+  // avoid possibly legacy enterprise assets URLs and asset image URLs
+  // that don't have the cache-busting piece in it.
+  app.use('/assets/cb-', setManualFastlySurrogateKey)
   app.use(
-    '/assets',
+    '/assets/',
     express.static('assets', {
       index: false,
       etag: false,
       lastModified: false,
-      maxAge: '1 day', // Relatively short in case we update images
+      // Can be aggressive because images inside the content get unique
+      // URLs with a cache busting prefix.
+      maxAge: '7 days',
     })
   )
   app.use(
-    '/public',
+    '/public/',
     express.static('data/graphql', {
       index: false,
       etag: false,