aggressive cache-control on archived redirects (#23091)

Part of #1271

Author: Peter Bengtsson

middleware/archived-enterprise-versions-assets.js

@@ -1,9 +1,12 @@
 import path from 'path'
+
+import got from 'got'
+
 import patterns from '../lib/patterns.js'
 import isArchivedVersion from '../lib/is-archived-version.js'
-import got from 'got'
+import { cacheControlFactory } from './cache-control.js'
 
-const ONE_DAY = 24 * 60 * 60 // 1 day in seconds
+const cacheControl = cacheControlFactory(60 * 60 * 24)
 
 // This module handles requests for the CSS and JS assets for
 // deprecated GitHub Enterprise versions by routing them to static content in
@@ -31,7 +34,7 @@ export default async function archivedEnterpriseVersionsAssets(req, res, next) {
     res.set('x-is-archived', 'true')
     res.set('x-robots-tag', 'noindex')
     // Allow the browser and Fastly to cache these
-    res.set('cache-control', `public, max-age=${ONE_DAY}`)
+    cacheControl(res)
     return res.send(r.body)
   } catch (err) {
     return next(404)

middleware/archived-enterprise-versions.js

@@ -9,13 +9,16 @@ import versionSatisfiesRange from '../lib/version-satisfies-range.js'
 import isArchivedVersion from '../lib/is-archived-version.js'
 import got from 'got'
 import readJsonFile from '../lib/read-json-file.js'
+import { cacheControlFactory } from './cache-control.js'
 const archivedRedirects = readJsonFile(
   './lib/redirects/static/archived-redirects-from-213-to-217.json'
 )
 const archivedFrontmatterFallbacks = readJsonFile(
   './lib/redirects/static/archived-frontmatter-fallbacks.json'
 )
 
+const cacheControl = cacheControlFactory(60 * 60 * 24 * 365)
+
 async function getRemoteJSON(url) {
   if (_getRemoteJSONCache.has(url)) {
     return _getRemoteJSONCache.get(url)
@@ -42,6 +45,7 @@ export default async function archivedEnterpriseVersions(req, res, next) {
     req.path.startsWith('/en/') &&
     versionSatisfiesRange(requestedVersion, `<${firstVersionDeprecatedOnNewSite}`)
   ) {
+    cacheControl(res)
     return res.redirect(301, req.baseUrl + req.path.replace(/^\/en/, ''))
   }
 
@@ -53,6 +57,7 @@ export default async function archivedEnterpriseVersions(req, res, next) {
   ) {
     const redirect = archivedRedirects[req.path]
     if (redirect && redirect !== req.path) {
+      cacheControl(res)
       return res.redirect(301, redirect)
     }
   }
@@ -64,6 +69,7 @@ export default async function archivedEnterpriseVersions(req, res, next) {
       // make redirects found via redirects.json redirect with a 301
       if (redirectJson[req.path]) {
         res.set('x-robots-tag', 'noindex')
+        cacheControl(res)
         return res.redirect(301, redirectJson[req.path])
       }
     } catch (err) {
@@ -78,6 +84,7 @@ export default async function archivedEnterpriseVersions(req, res, next) {
     // make stubbed redirect files (which exist in versions <2.13) redirect with a 301
     const staticRedirect = r.body.match(patterns.staticRedirect)
     if (staticRedirect) {
+      cacheControl(res)
       return res.redirect(301, staticRedirect[1])
     }
 
@@ -87,6 +94,7 @@ export default async function archivedEnterpriseVersions(req, res, next) {
     for (const fallbackRedirect of getFallbackRedirects(req, requestedVersion) || []) {
       try {
         await got(getProxyPath(fallbackRedirect, requestedVersion))
+        cacheControl(res)
         return res.redirect(301, fallbackRedirect)
       } catch (err) {
         // noop

middleware/cache-control.js

@@ -0,0 +1,13 @@
+// Return a function you can pass a Response object to and it will
+// set the `Cache-Control` header.
+//
+// For example:
+//
+//    const cacheControlYear = getCacheControl(60 * 60 * 24 * 365)
+//    ...
+//    cacheControlYear(res)
+//    res.send(body)
+//
+export function cacheControlFactory(maxAge = 60 * 60, public_ = true) {
+  return (res) => res.set('cache-control', `${public_ ? 'public, ' : ''}max-age=${maxAge}`)
+}