feat(server): add config option to define etag hash function (#6438)

packages/config/src/options.js

@@ -219,6 +219,21 @@ export function getNuxtConfig (_options) {
     options.debug = options.dev
   }
 
+  // Validate that etag.hash is a function, if not unset it
+  if (options.render.etag) {
+    const { hash } = options.render.etag
+    if (hash) {
+      const isFn = typeof hash === 'function'
+      if (!isFn) {
+        options.render.etag.hash = undefined
+
+        if (options.dev) {
+          consola.warn(`render.etag.hash should be a function, received ${typeof hash} instead`)
+        }
+      }
+    }
+  }
+
   // Apply default hash to CSP option
   if (options.render.csp) {
     options.render.csp = defaults({}, options.render.csp, {

packages/config/test/options.test.js

@@ -87,6 +87,16 @@ describe('config: options', () => {
     expect(store).toEqual(true)
   })
 
+  test('should unset and warn when etag.hash not a function', () => {
+    const { render: { etag } } = getNuxtConfig({ render: { etag: { hash: true } } })
+    expect(etag).toMatchObject({ hash: undefined })
+    expect(consola.warn).not.toHaveBeenCalledWith('render.etag.hash should be a function, received boolean instead')
+
+    const { render: { etag: etagDev } } = getNuxtConfig({ dev: true, render: { etag: { hash: true } } })
+    expect(etagDev).toMatchObject({ hash: undefined })
+    expect(consola.warn).toHaveBeenCalledWith('render.etag.hash should be a function, received boolean instead')
+  })
+
   test('should enable csp', () => {
     const { render: { csp } } = getNuxtConfig({ render: { csp: { allowedSources: true, test: true } } })
     expect(csp).toEqual({

packages/server/src/middleware/nuxt.js

@@ -38,7 +38,8 @@ export default ({ options, nuxt, renderRoute, resources }) => async function nux
 
     // Add ETag header
     if (!error && options.render.etag) {
-      const etag = generateETag(html, options.render.etag)
+      const { hash } = options.render.etag
+      const etag = hash ? hash(html, options.render.etag) : generateETag(html, options.render.etag)
       if (fresh(req.headers, { etag })) {
         res.statusCode = 304
         res.end()

packages/server/test/middleware/nuxt.test.js

@@ -117,6 +117,22 @@ describe('server: nuxtMiddleware', () => {
     expect(res.setHeader).nthCalledWith(1, 'ETag', 'etag-hash')
   })
 
+  test('should set etag after rendering through hook', async () => {
+    const context = createContext()
+    const hash = jest.fn(() => 'etag-hook')
+    context.options.render.etag = { hash }
+
+    const result = { html: 'rendered html' }
+    context.renderRoute.mockReturnValue(result)
+    const nuxtMiddleware = createNuxtMiddleware(context)
+    const { req, res, next } = createServerContext()
+
+    await nuxtMiddleware(req, res, next)
+
+    expect(hash).toBeCalledWith('rendered html', expect.any(Object))
+    expect(res.setHeader).nthCalledWith(1, 'ETag', 'etag-hook')
+  })
+
   test('should return 304 if request is fresh', async () => {
     const context = createContext()
     const result = { html: 'rendered html' }