feat: add experimental support for TTL (#833)

* feat: wip ttl support

* chore: add debug headers

* fix: ttl parsing

* chore: move utils into helpers file

* chore: add jest ts support

* chore: change from review

Author: ascorbic

babel.config.js

@@ -1,4 +1,4 @@
 // This is just for jest
 module.exports = {
-  presets: [['@babel/preset-env', { targets: { node: 'current' } }]],
+  presets: [['@babel/preset-env', { targets: { node: 'current' } }], '@babel/preset-typescript'],
 }

demos/default/pages/getStaticProps/withRevalidate/[id].js

@@ -8,7 +8,7 @@ const Show = ({ show, time }) => (
 
     <h1>Show #{show.id}</h1>
     <p>{show.name}</p>
-    <p>Rendered at {time}</p>
+    <p>Rendered at {time} (slowly)</p>
     <hr />
 
     <Link href="/">
@@ -33,7 +33,7 @@ export async function getStaticProps({ params }) {
   const res = await fetch(`https://api.tvmaze.com/shows/${id}`)
   const data = await res.json()
   const time = new Date().toLocaleTimeString()
-  await new Promise((resolve) => setTimeout(resolve, 1000))
+  await new Promise((resolve) => setTimeout(resolve, 3000))
   return {
     props: {
       show: data,

package-lock.json

@@ -72,6 +72,7 @@
   "devDependencies": {
     "@babel/core": "^7.15.8",
     "@babel/preset-env": "^7.15.8",
+    "@babel/preset-typescript": "^7.16.0",
     "@netlify/build": "^18.25.2",
     "@netlify/eslint-config-node": "^3.3.7",
     "@testing-library/cypress": "^8.0.1",

package.json

@@ -129,7 +129,7 @@ exports.generateRedirects = async ({ netlifyConfig, basePath, i18n }) => {
     // ISR redirects are handled by the regular function. Forced to avoid pre-rendered pages
     ...isrRedirects.map((redirect) => ({
       from: `${basePath}${redirect}`,
-      to: HANDLER_FUNCTION_PATH,
+      to: process.env.EXPERIMENTAL_ODB_TTL ? ODB_FUNCTION_PATH : HANDLER_FUNCTION_PATH,
       status: 200,
       force: true,
     })),

src/helpers/config.js

@@ -2,7 +2,7 @@
 const { cpus } = require('os')
 
 const { yellowBright } = require('chalk')
-const { existsSync, readJson, move, cpSync, copy, writeJson } = require('fs-extra')
+const { existsSync, readJson, move, cpSync, copy, writeJson, readFile, writeFile } = require('fs-extra')
 const globby = require('globby')
 const { outdent } = require('outdent')
 const pLimit = require('p-limit')
@@ -219,6 +219,57 @@ exports.moveStaticPages = async ({ netlifyConfig, target, i18n }) => {
   }
 }
 
+const patchFile = async ({ file, from, to }) => {
+  if (!existsSync(file)) {
+    return
+  }
+  const content = await readFile(file, 'utf8')
+  if (content.includes(to)) {
+    return
+  }
+  const newContent = content.replace(from, to)
+  await writeFile(`${file}.orig`, content)
+  await writeFile(file, newContent)
+}
+
+const getServerFile = (root) => {
+  let serverFile
+  try {
+    serverFile = require.resolve('next/dist/server/next-server', { paths: [root] })
+  } catch {
+    // Ignore
+  }
+  if (!serverFile) {
+    try {
+      // eslint-disable-next-line node/no-missing-require
+      serverFile = require.resolve('next/dist/next-server/server/next-server', { paths: [root] })
+    } catch {
+      // Ignore
+    }
+  }
+  return serverFile
+}
+
+exports.patchNextFiles = async (root) => {
+  const serverFile = getServerFile(root)
+  console.log(`Patching ${serverFile}`)
+  if (serverFile) {
+    await patchFile({
+      file: serverFile,
+      from: `let ssgCacheKey = `,
+      to: `let ssgCacheKey = process.env._BYPASS_SSG || `,
+    })
+  }
+}
+
+exports.unpatchNextFiles = async (root) => {
+  const serverFile = getServerFile(root)
+  const origFile = `${serverFile}.orig`
+  if (existsSync(origFile)) {
+    await move(origFile, serverFile, { overwrite: true })
+  }
+}
+
 exports.movePublicFiles = async ({ appDir, publish }) => {
   const publicDir = join(appDir, 'public')
   if (existsSync(publicDir)) {

src/helpers/files.js

@@ -3,7 +3,7 @@ const { join, relative } = require('path')
 const { ODB_FUNCTION_NAME } = require('./constants')
 const { restoreCache, saveCache } = require('./helpers/cache')
 const { getNextConfig, configureHandlerFunctions, generateRedirects } = require('./helpers/config')
-const { moveStaticPages, movePublicFiles } = require('./helpers/files')
+const { moveStaticPages, movePublicFiles, patchNextFiles, unpatchNextFiles } = require('./helpers/files')
 const { generateFunctions, setupImageFunction, generatePagesResolver } = require('./helpers/functions')
 const {
   verifyNetlifyBuildVersion,
@@ -56,6 +56,10 @@ module.exports = {
 
     await movePublicFiles({ appDir, publish })
 
+    if (process.env.EXPERIMENTAL_ODB_TTL) {
+      await patchNextFiles(basePath)
+    }
+
     if (process.env.EXPERIMENTAL_MOVE_STATIC_PAGES) {
       console.log(
         "The flag 'EXPERIMENTAL_MOVE_STATIC_PAGES' is no longer required, as it is now the default. To disable this behavior, set the env var 'SERVE_STATIC_FILES_FROM_ORIGIN' to 'true'",
@@ -75,10 +79,12 @@ module.exports = {
     })
   },
 
-  async onPostBuild({ netlifyConfig, utils: { cache, functions }, constants: { FUNCTIONS_DIST } }) {
+  async onPostBuild({ netlifyConfig, utils: { cache, functions, failBuild }, constants: { FUNCTIONS_DIST } }) {
     await saveCache({ cache, publish: netlifyConfig.build.publish })
     await checkForOldFunctions({ functions })
     await checkZipSize(join(FUNCTIONS_DIST, `${ODB_FUNCTION_NAME}.zip`))
+    const { basePath } = await getNextConfig({ publish: netlifyConfig.build.publish, failBuild })
+    await unpatchNextFiles(basePath)
   },
   onEnd() {
     logBetaMessage()

src/index.js

@@ -5,7 +5,7 @@ const path = require('path')
 
 const { Bridge } = require('@vercel/node/dist/bridge')
 
-const { downloadFile } = require('./handlerUtils')
+const { downloadFile, getMaxAge, getMultiValueHeaders } = require('./handlerUtils')
 
 const makeHandler =
   () =>
@@ -17,6 +17,10 @@ const makeHandler =
       // eslint-disable-next-line node/no-missing-require
       require.resolve('./pages.js')
     } catch {}
+    // eslint-disable-next-line no-underscore-dangle
+    process.env._BYPASS_SSG = 'true'
+
+    const ONE_YEAR_IN_SECONDS = 31536000
 
     // We don't want to write ISR files to disk in the lambda environment
     conf.experimental.isrFlushToDisk = false
@@ -106,6 +110,7 @@ const makeHandler =
     bridge.listen()
 
     return async (event, context) => {
+      let requestMode = mode
       // Ensure that paths are encoded - but don't double-encode them
       event.path = new URL(event.path, event.rawUrl).pathname
       // Next expects to be able to parse the query from the URL
@@ -118,17 +123,12 @@ const makeHandler =
         base = `${protocol}://${host}`
       }
       const { headers, ...result } = await bridge.launcher(event, context)
+
       /** @type import("@netlify/functions").HandlerResponse */
 
       // Convert all headers to multiValueHeaders
-      const multiValueHeaders = {}
-      for (const key of Object.keys(headers)) {
-        if (Array.isArray(headers[key])) {
-          multiValueHeaders[key] = headers[key]
-        } else {
-          multiValueHeaders[key] = [headers[key]]
-        }
-      }
+
+      const multiValueHeaders = getMultiValueHeaders(headers)
 
       if (multiValueHeaders['set-cookie']?.[0]?.includes('__prerender_bypass')) {
         delete multiValueHeaders.etag
@@ -137,12 +137,20 @@ const makeHandler =
 
       // Sending SWR headers causes undefined behaviour with the Netlify CDN
       const cacheHeader = multiValueHeaders['cache-control']?.[0]
+
       if (cacheHeader?.includes('stale-while-revalidate')) {
-        console.log({ cacheHeader })
+        if (requestMode === 'odb' && process.env.EXPERIMENTAL_ODB_TTL) {
+          requestMode = 'isr'
+          const ttl = getMaxAge(cacheHeader)
+          // Long-expiry TTL is basically no TTL
+          if (ttl > 0 && ttl < ONE_YEAR_IN_SECONDS) {
+            result.ttl = ttl
+          }
+          multiValueHeaders['x-rendered-at'] = [new Date().toISOString()]
+        }
         multiValueHeaders['cache-control'] = ['public, max-age=0, must-revalidate']
       }
-      multiValueHeaders['x-render-mode'] = [mode]
-
+      multiValueHeaders['x-render-mode'] = [requestMode]
       return {
         ...result,
         multiValueHeaders,
@@ -157,7 +165,7 @@ const { tmpdir } = require('os')
 const { promises, existsSync } = require("fs");
 // We copy the file here rather than requiring from the node module
 const { Bridge } = require("./bridge");
-const { downloadFile } = require('./handlerUtils')
+const { downloadFile, getMaxAge, getMultiValueHeaders } = require('./handlerUtils')
 
 const { builder } = require("@netlify/functions");
 const { config }  = require("${publishDir}/required-server-files.json")

src/templates/getHandler.js

@@ -6,7 +6,7 @@ import { promisify } from 'util'
 
 const streamPipeline = promisify(pipeline)
 
-export const downloadFile = async (url, destination) => {
+export const downloadFile = async (url: string, destination: string): Promise<void> => {
   console.log(`Downloading ${url} to ${destination}`)
 
   const httpx = url.startsWith('https') ? https : http
@@ -31,3 +31,35 @@ export const downloadFile = async (url, destination) => {
     })
   })
 }
+
+export const getMaxAge = (header: string): number => {
+  const parts = header.split(',')
+  let maxAge
+  for (const part of parts) {
+    const [key, value] = part.split('=')
+    if (key?.trim() === 's-maxage') {
+      maxAge = value?.trim()
+    }
+  }
+  if (maxAge) {
+    const result = Number.parseInt(maxAge)
+    return Number.isNaN(result) ? 0 : result
+  }
+  return 0
+}
+
+export const getMultiValueHeaders = (
+  headers: Record<string, string | Array<string>>,
+): Record<string, Array<string>> => {
+  const multiValueHeaders: Record<string, Array<string>> = {}
+  for (const key of Object.keys(headers)) {
+    const header = headers[key]
+
+    if (Array.isArray(header)) {
+      multiValueHeaders[key] = header
+    } else {
+      multiValueHeaders[key] = [header]
+    }
+  }
+  return multiValueHeaders
+}

src/templates/handlerUtils.ts

@@ -353,6 +353,8 @@ describe('onBuild()', () => {
 
 describe('onPostBuild', () => {
   test('saves cache with right paths', async () => {
+    await moveNextDist()
+
     const save = jest.fn()
 
     await plugin.onPostBuild({
@@ -366,6 +368,8 @@ describe('onPostBuild', () => {
   })
 
   test('warns if old functions exist', async () => {
+    await moveNextDist()
+
     const list = jest.fn().mockResolvedValue([
       {
         name: 'next_test',