Implement ETag support for server rendered pages. (#1693)

package.json

@@ -61,8 +61,10 @@
     "case-sensitive-paths-webpack-plugin": "2.0.0",
     "cross-spawn": "5.1.0",
     "del": "2.2.2",
+    "etag": "1.8.0",
+    "fresh": "0.5.0",
     "friendly-errors-webpack-plugin": "1.5.0",
-    "glob": "^7.1.1",
+    "glob": "7.1.1",
     "glob-promise": "3.1.0",
     "htmlescape": "1.1.1",
     "http-status": "1.0.1",

server/index.js

@@ -225,7 +225,7 @@ export default class Server {
       res.setHeader('X-Powered-By', `Next.js ${pkg.version}`)
     }
     const html = await this.renderToHTML(req, res, pathname, query)
-    return sendHTML(res, html, req.method)
+    return sendHTML(req, res, html, req.method)
   }
 
   async renderToHTML (req, res, pathname, query) {
@@ -253,7 +253,7 @@ export default class Server {
 
   async renderError (err, req, res, pathname, query) {
     const html = await this.renderErrorToHTML(err, req, res, pathname, query)
-    return sendHTML(res, html, req.method)
+    return sendHTML(req, res, html, req.method)
   }
 
   async renderErrorToHTML (err, req, res, pathname, query) {

server/render.js

@@ -2,6 +2,8 @@ import { join } from 'path'
 import { createElement } from 'react'
 import { renderToString, renderToStaticMarkup } from 'react-dom/server'
 import send from 'send'
+import generateETag from 'etag'
+import fresh from 'fresh'
 import requireModule from './require'
 import getConfig from './config'
 import resolvePath from './resolve'
@@ -13,7 +15,7 @@ import ErrorDebug from '../lib/error-debug'
 
 export async function render (req, res, pathname, query, opts) {
   const html = await renderToHTML(req, res, pathname, opts)
-  sendHTML(res, html, req.method)
+  sendHTML(req, res, html, req.method)
 }
 
 export function renderToHTML (req, res, pathname, query, opts) {
@@ -22,7 +24,7 @@ export function renderToHTML (req, res, pathname, query, opts) {
 
 export async function renderError (err, req, res, pathname, query, opts) {
   const html = await renderErrorToHTML(err, req, res, query, opts)
-  sendHTML(res, html, req.method)
+  sendHTML(req, res, html, req.method)
 }
 
 export function renderErrorToHTML (err, req, res, pathname, query, opts = {}) {
@@ -148,9 +150,17 @@ export async function renderScriptError (req, res, page, error, customFields, op
   `)
 }
 
-export function sendHTML (res, html, method) {
+export function sendHTML (req, res, html, method) {
   if (res.finished) return
+  const etag = generateETag(html)
 
+  if (fresh(req.headers, { etag })) {
+    res.statusCode = 304
+    res.end()
+    return
+  }
+
+  res.setHeader('ETag', etag)
   res.setHeader('Content-Type', 'text/html')
   res.setHeader('Content-Length', Buffer.byteLength(html))
   res.end(method === 'HEAD' ? null : html)

test/integration/basic/test/misc.js

@@ -1,4 +1,5 @@
 /* global describe, test, expect */
+import fetch from 'node-fetch'
 
 export default function (context) {
   describe('Misc', () => {
@@ -12,5 +13,14 @@ export default function (context) {
       const html = await context.app.renderToHTML({}, res, '/finish-response', {})
       expect(html).toBeFalsy()
     })
+
+    test('allow etag header support', async () => {
+      const url = `http://localhost:${context.appPort}/stateless`
+      const etag = (await fetch(url)).headers.get('ETag')
+
+      const headers = { 'If-None-Match': etag }
+      const res2 = await fetch(url, { headers })
+      expect(res2.status).toBe(304)
+    })
   })
 }

test/integration/basic/test/xpowered-by.js

@@ -4,7 +4,7 @@ import { pkg } from 'next-test-utils'
 export default function ({ app }) {
   describe('X-Powered-By header', () => {
     test('set it by default', async () => {
-      const req = { url: '/stateless' }
+      const req = { url: '/stateless', headers: {} }
       const headers = {}
       const res = {
         setHeader (key, value) {
@@ -18,7 +18,7 @@ export default function ({ app }) {
     })
 
     test('do not set it when poweredByHeader==false', async () => {
-      const req = { url: '/stateless' }
+      const req = { url: '/stateless', headers: {} }
       const originalConfigValue = app.config.poweredByHeader
       app.config.poweredByHeader = false
       const res = {

yarn.lock

@@ -1972,7 +1972,7 @@ esutils@^2.0.0, esutils@^2.0.2:
   version "2.0.2"
   resolved "https://registry.npmjs.org/esutils/-/esutils-2.0.2.tgz#0abf4f1caa5bcb1f7a9d8acc6dea4faaa04bac9b"
 
-etag@~1.8.0:
+etag@1.8.0, etag@~1.8.0:
   version "1.8.0"
   resolved "https://registry.npmjs.org/etag/-/etag-1.8.0.tgz#6f631aef336d6c46362b51764044ce216be3c051"
 
@@ -2331,17 +2331,7 @@ glob-promise@3.1.0:
   version "3.1.0"
   resolved "https://registry.npmjs.org/glob-promise/-/glob-promise-3.1.0.tgz#198882a3817be7dc2c55f92623aa9e7b3f82d1eb"
 
-glob@^6.0.1:
+glob@7.1.1, glob@^7.0.0, glob@^7.0.3, glob@^7.0.5, glob@^7.0.6, glob@^7.1.1:
-  version "6.0.4"
-  resolved "https://registry.npmjs.org/glob/-/glob-6.0.4.tgz#0f08860f6a155127b2fadd4f9ce24b1aab6e4d22"
-  dependencies:
-    inflight "^1.0.4"
-    inherits "2"
-    minimatch "2 || 3"
-    once "^1.3.0"
-    path-is-absolute "^1.0.0"
-
-glob@^7.0.0, glob@^7.0.3, glob@^7.0.5, glob@^7.0.6, glob@^7.1.1:
   version "7.1.1"
   resolved "https://registry.npmjs.org/glob/-/glob-7.1.1.tgz#805211df04faaf1c63a3600306cdf5ade50b2ec8"
   dependencies:
@@ -2352,6 +2342,16 @@ glob@^7.0.0, glob@^7.0.3, glob@^7.0.5, glob@^7.0.6, glob@^7.1.1:
     once "^1.3.0"
     path-is-absolute "^1.0.0"
 
+glob@^6.0.1:
+  version "6.0.4"
+  resolved "https://registry.npmjs.org/glob/-/glob-6.0.4.tgz#0f08860f6a155127b2fadd4f9ce24b1aab6e4d22"
+  dependencies:
+    inflight "^1.0.4"
+    inherits "2"
+    minimatch "2 || 3"
+    once "^1.3.0"
+    path-is-absolute "^1.0.0"
+
 global@^4.3.0:
   version "4.3.1"
   resolved "https://registry.npmjs.org/global/-/global-4.3.1.tgz#5f757908c7cbabce54f386ae440e11e26b7916df"