udpate middleware to read redirects from top-level redirects.json in archival repo

Author: sarahs

lib/enterprise-server-releases.js

@@ -47,8 +47,8 @@ const nextDeprecationDate = dates[oldestSupported].deprecationDate
 const isOldestReleaseDeprecated = new Date() > new Date(nextDeprecationDate)
 const deprecatedOnNewSite = deprecated.filter(version => versionSatisfiesRange(version, '>=2.13'))
 const firstVersionDeprecatedOnNewSite = '2.13'
-// starting from 2.18, we updated the archival script to create stubbed HTML redirect files
-const lastVersionWithoutStubbedRedirectFiles = '2.17'
+// starting from 2.18, we updated the archival script to create a redirects.json top-level file in the archived repo
+const lastVersionWithoutArchivedRedirectsFile = '2.17'
 // last version using paths like /enterprise/<release>/<user>/<product>/<category>/<article>
 // instead of /enterprise-server@<release>/<product>/<category>/<article>
 const lastReleaseWithLegacyFormat = '2.18'
@@ -68,7 +68,7 @@ module.exports = {
   deprecatedOnNewSite,
   dates,
   firstVersionDeprecatedOnNewSite,
-  lastVersionWithoutStubbedRedirectFiles,
+  lastVersionWithoutArchivedRedirectsFile,
   lastReleaseWithLegacyFormat,
   deprecatedReleasesWithLegacyFormat,
   deprecatedReleasesWithNewFormat,

middleware/archived-enterprise-versions.js

@@ -1,6 +1,6 @@
 const path = require('path')
 const slash = require('slash')
-const { firstVersionDeprecatedOnNewSite, lastVersionWithoutStubbedRedirectFiles } = require('../lib/enterprise-server-releases')
+const { firstVersionDeprecatedOnNewSite, lastVersionWithoutArchivedRedirectsFile } = require('../lib/enterprise-server-releases')
 const patterns = require('../lib/patterns')
 const versionSatisfiesRange = require('../lib/version-satisfies-range')
 const isArchivedVersion = require('../lib/is-archived-version')
@@ -25,21 +25,37 @@ module.exports = async (req, res, next) => {
   }
 
   // find redirects for versions between 2.13 and 2.17
-  // starting with 2.18, we updated the archival script to create stubbed HTML redirect files
+  // starting with 2.18, we updated the archival script to create a redirects.json file
   if (versionSatisfiesRange(requestedVersion, `>=${firstVersionDeprecatedOnNewSite}`) &&
-    versionSatisfiesRange(requestedVersion, `<=${lastVersionWithoutStubbedRedirectFiles}`)) {
+    versionSatisfiesRange(requestedVersion, `<=${lastVersionWithoutArchivedRedirectsFile}`)) {
     const redirect = archvivedRedirects[req.path]
     if (redirect && redirect !== req.path) {
       return res.redirect(301, redirect)
     }
   }
 
+  let reqPath = req.path
+  let isRedirect = false
+  if (versionSatisfiesRange(requestedVersion, `>${lastVersionWithoutArchivedRedirectsFile}`)) {
+    const redirectJson = await got(getProxyPath('redirects.json', requestedVersion))
+    if (redirectJson[req.path]) {
+      isRedirect = true
+    }
+    reqPath = redirectJson[req.path] || req.path
+  }
+
   try {
-    const r = await got(getProxyPath(req.path, requestedVersion))
+    const r = await got(getProxyPath(reqPath, requestedVersion))
     res.set('content-type', r.headers['content-type'])
     res.set('x-robots-tag', 'noindex')
 
-    // make the stubbed redirect files added in >=2.18 return 301 instead of 200
+    // make redirects found via redirects.json return 301 instead of 200
+    if (isRedirect) {
+      res.status(301)
+      res.set('location', reqPath)
+    }
+
+    // make stubbed redirect files (which exist in versions <2.13) return 301 instead of 200
     const staticRedirect = r.body.match(patterns.staticRedirect)
     if (staticRedirect) {
       res.status(301)
@@ -73,7 +89,7 @@ function getProxyPath (reqPath, requestedVersion) {
 // this workaround finds potentially relevant frontmatter redirects in currently supported pages
 function getFallbackRedirects (req, requestedVersion) {
   if (versionSatisfiesRange(requestedVersion, `<${firstVersionDeprecatedOnNewSite}`)) return
-  if (versionSatisfiesRange(requestedVersion, `>${lastVersionWithoutStubbedRedirectFiles}`)) return
+  if (versionSatisfiesRange(requestedVersion, `>${lastVersionWithoutArchivedRedirectsFile}`)) return
 
   return archivedFrontmatterFallbacks.find(arrayOfFallbacks => arrayOfFallbacks.includes(req.path))
 }