skip generating cert each time (#67122)

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Closes NEXT-
Fixes https://github.com/vercel/next.js/discussions/67120

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---------

Co-authored-by: JJ Kasper <[email protected]>

packages/next/src/lib/mkcert.ts

@@ -1,8 +1,9 @@
-import fs from 'fs'
-import path from 'path'
+import fs from 'node:fs'
+import path from 'node:path'
+import { X509Certificate, createPrivateKey } from 'node:crypto'
 import { getCacheDirectory } from './helpers/get-cache-directory'
 import * as Log from '../build/output/log'
-import { execSync } from 'child_process'
+import { execSync } from 'node:child_process'
 const { WritableStream } = require('node:stream/web') as {
   WritableStream: typeof global.WritableStream
 }
@@ -112,6 +113,25 @@ export async function createSelfSignedCertificate(
     const keyPath = path.resolve(resolvedCertDir, 'localhost-key.pem')
     const certPath = path.resolve(resolvedCertDir, 'localhost.pem')
 
+    if (fs.existsSync(keyPath) && fs.existsSync(certPath)) {
+      const cert = new X509Certificate(fs.readFileSync(certPath))
+      const key = fs.readFileSync(keyPath)
+
+      if (
+        cert.checkHost(host ?? 'localhost') &&
+        cert.checkPrivateKey(createPrivateKey(key))
+      ) {
+        Log.info('Using already generated self signed certificate')
+        const caLocation = execSync(`"${binaryPath}" -CAROOT`).toString().trim()
+
+        return {
+          key: keyPath,
+          cert: certPath,
+          rootCA: `${caLocation}/rootCA.pem`,
+        }
+      }
+    }
+
     Log.info(
       'Attempting to generate self signed certificate. This may prompt for your password'
     )

test/development/experimental-https-server/https-server.generated-key.test.ts

@@ -33,4 +33,13 @@ describe('experimental-https-server (generated certificate)', () => {
     const html = await renderViaHTTP(next.url, '/2', undefined, { agent })
     expect(html).toContain('Hello from Pages')
   })
+
+  it('should successfully reuse generated certificates', async () => {
+    await next.stop()
+    await next.start()
+    expect(next.url).toInclude('https://')
+    expect(next.cliOutput).toContain(
+      'Using already generated self signed certificate'
+    )
+  })
 })

test/lib/next-modes/base.ts

@@ -79,8 +79,6 @@ export class NextInstance {
     this.env = {}
     Object.assign(this, opts)
 
-    require('console').log('packageJson??', this.packageJson)
-
     if (!isNextDeploy) {
       this.env = {
         ...this.env,