feat: add nextjs middleware handling (github#19139)

* feat: add nextjs middleware handling split

* fix: eslint errors

* fix: filter boolean from csp list

* fix: feature flag nextjs server start

* feat: add prettier rules for ts,tsx files

* fix: remove unnecessary async from next middleware

* fix: next middleware name

* Update tsconfig.json

Co-authored-by: James M. Greene <JamesMGreene@github.com>

* Update next-env.d.ts

Co-authored-by: James M. Greene <JamesMGreene@github.com>

* fix: add typescript linting to lint command

* add comment for unsafe-eval, update webpack to use eval in development

* fix: feature flag typo

Co-authored-by: James M. Greene <JamesMGreene@github.com>

.gitignore

@@ -10,6 +10,7 @@ coverage/
 /content/early-access
 /data/early-access
 dist
+.next
 
 # blc: broken link checker
 blc_output.log

.prettierrc.json

@@ -1,12 +1,20 @@
 {
   "overrides": [
     {
-      "files":[
-        "**/*.{yml,yaml}"
-      ],
+      "files": ["**/*.{yml,yaml}"],
       "options": {
         "singleQuote": true
       }
+    },
+    {
+      "files": ["**/*.{ts,tsx}"],
+      "options": {
+        "semi": false,
+        "singleQuote": true,
+        "printWidth": 100,
+        "jsxBracketSameLine": false,
+        "arrowParens": "always"
+      }
     }
   ]
 }

components/ExampleComponent.tsx

@@ -0,0 +1,3 @@
+export const ExampleComponent = () => {
+  return <div>Welcome to Next.JS land!</div>
+}

feature-flags.json

@@ -1,5 +1,6 @@
 {
   "FEATURE_TEST_TRUE": true,
   "FEATURE_TEST_FALSE": false,
-  "FEATURE_NEW_SITETREE": false
+  "FEATURE_NEW_SITETREE": false,
+  "FEATURE_NEXTJS": false
 }

middleware/csp.js

@@ -35,8 +35,11 @@ module.exports = function csp (req, res, next) {
       ],
       scriptSrc: [
         "'self'",
-        'data:'
-      ],
+        'data:',
+        // For use during development only! This allows us to use a performant webpack devtool setting (eval)
+        // https://webpack.js.org/configuration/devtool/#devtool
+        process.env.NODE_ENV === 'development' && "'unsafe-eval'"
+      ].filter(Boolean),
       frameSrc: [ // exceptions for GraphQL Explorer
         'https://graphql-explorer.githubapp.com', // production env
         'https://graphql.github.com/',

middleware/index.js

@@ -137,6 +137,11 @@ module.exports = function (app) {
   // *** Headers for pages only ***
   app.use(require('./set-fastly-cache-headers'))
 
+  // handle serving NextJS bundled code (/_next/*)
+  if (process.env.FEATURE_NEXTJS) {
+    app.use(instrument('./next'))
+  }
+
   // Check for a dropped connection before proceeding (again)
   app.use(haltOnDroppedConnection)
 

middleware/next.js

@@ -0,0 +1,21 @@
+const next = require('next')
+
+const { NODE_ENV, FEATURE_NEXTJS } = process.env
+const isDevelopment = NODE_ENV === 'development'
+
+let nextHandleRequest
+if (FEATURE_NEXTJS) {
+  const nextApp = next({ dev: isDevelopment })
+  nextHandleRequest = nextApp.getRequestHandler()
+  nextApp.prepare()
+}
+
+module.exports = function renderPageWithNext (req, res, next) {
+  if (req.path.startsWith('/_next/')) {
+    return nextHandleRequest(req, res)
+  }
+
+  next()
+}
+
+module.exports.nextHandleRequest = nextHandleRequest

middleware/render-page.js

@@ -7,8 +7,9 @@ const Page = require('../lib/page')
 const statsd = require('../lib/statsd')
 const RedisAccessor = require('../lib/redis-accessor')
 const { isConnectionDropped } = require('./halt-on-dropped-connection')
+const { nextHandleRequest } = require('./next')
 
-const { HEROKU_RELEASE_VERSION } = process.env
+const { HEROKU_RELEASE_VERSION, FEATURE_NEXTJS } = process.env
 const pageCacheDatabaseNumber = 1
 const pageCacheExpiration = 24 * 60 * 60 * 1000 // 24 hours
 
@@ -25,6 +26,12 @@ const pageCache = new RedisAccessor({
 // a list of query params that *do* alter the rendered page, and therefore should be cached separately
 const cacheableQueries = ['learn']
 
+const renderWithNext = FEATURE_NEXTJS
+  ? [
+      '/en/rest'
+    ]
+  : []
+
 function addCsrf (req, text) {
   return text.replace('$CSRFTOKEN$', req.csrfToken())
 }
@@ -65,7 +72,10 @@ module.exports = async function renderPage (req, res, next) {
   // Is the request for JSON debugging info?
   const isRequestingJsonForDebugging = 'json' in req.query && process.env.NODE_ENV !== 'production'
 
-  if (isCacheable && !isRequestingJsonForDebugging) {
+  // Should the current path be rendered by NextJS?
+  const isNextJsRequest = renderWithNext.includes(req.path)
+
+  if (isCacheable && !isRequestingJsonForDebugging && !(FEATURE_NEXTJS && isNextJsRequest)) {
     // Stop processing if the connection was already dropped
     if (isConnectionDropped(req, res)) return
 
@@ -136,15 +146,19 @@ module.exports = async function renderPage (req, res, next) {
     }
   }
 
-  // currentLayout is added to the context object in middleware/contextualizers/layouts
-  const output = await liquid.parseAndRender(req.context.currentLayout, context)
+  if (FEATURE_NEXTJS && isNextJsRequest) {
+    nextHandleRequest(req, res)
+  } else {
+    // currentLayout is added to the context object in middleware/contextualizers/layouts
+    const output = await liquid.parseAndRender(req.context.currentLayout, 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(addCsrf(req, output))
+    // 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(addCsrf(req, output))
 
-  // Finally, save output to cache for the next time around
-  if (isCacheable) {
-    await pageCache.set(originalUrl, output, { expireIn: pageCacheExpiration })
+    // Finally, save output to cache for the next time around
+    if (isCacheable) {
+      await pageCache.set(originalUrl, output, { expireIn: pageCacheExpiration })
+    }
   }
 }

next-env.d.ts

@@ -0,0 +1,2 @@
+/// <reference types="next" />
+/// <reference types="next/types/global" />

next.config.js

@@ -0,0 +1,17 @@
+const { productIds } = require('./lib/all-products')
+
+module.exports = {
+  i18n: {
+    locales: ['en', 'ja'],
+    defaultLocale: 'en'
+  },
+  async rewrites () {
+    const defaultVersionId = 'free-pro-team@latest'
+    return productIds.map((productId) => {
+      return {
+        source: `/${productId}/:path*`,
+        destination: `/${defaultVersionId}/${productId}/:path*`
+      }
+    })
+  }
+}