fix: force serverless target

helpers/doesNotNeedPlugin.js

@@ -1,20 +1,14 @@
 const findUp = require('find-up')
 
 // Checks all the cases for which the plugin should do nothing
-const isStaticExportProject = require('./isStaticExportProject')
 const doesSiteUseNextOnNetlify = require('./doesSiteUseNextOnNetlify')
-const hasCorrectNextConfig = require('./hasCorrectNextConfig')
+const isStaticExportProject = require('./isStaticExportProject')
 
-const doesNotNeedPlugin = async ({ netlifyConfig, packageJson, failBuild }) => {
+const doesNotNeedPlugin = ({ netlifyConfig, packageJson }) => {
   const { build } = netlifyConfig
-  const { name, scripts = {} } = packageJson
-  const nextConfigPath = await findUp('next.config.js')
+  const { scripts = {} } = packageJson
 
-  return (
-    isStaticExportProject({ build, scripts }) ||
-    doesSiteUseNextOnNetlify({ packageJson }) ||
-    !(await hasCorrectNextConfig({ nextConfigPath, failBuild }))
-  )
+  return isStaticExportProject({ build, scripts }) || doesSiteUseNextOnNetlify({ packageJson })
 }
 
 module.exports = doesNotNeedPlugin

helpers/getNextConfig.js

@@ -1,7 +1,6 @@
 'use strict'
 
 const { cwd: getCwd } = require('process')
-const { resolve } = require('path')
 
 const moize = require('moize')
 

helpers/verifyBuildTarget.js

@@ -0,0 +1,38 @@
+const getNextConfig = require('./getNextConfig')
+// Checks if site has the correct next.config.js
+const verifyBuildTarget = async ({ failBuild }) => {
+  const { target } = await getNextConfig(failBuild)
+
+  // If the next config exists, log warning if target isnt in acceptableTargets
+  const acceptableTargets = ['serverless', 'experimental-serverless-trace']
+  const isValidTarget = acceptableTargets.includes(target)
+  if (isValidTarget) {
+    return
+  }
+  console.log(
+    `The "target" config property must be one of "${acceptableTargets.join(
+      '", "',
+    )}". Building with "serverless" target.`,
+  )
+
+  /* eslint-disable fp/no-delete, node/no-unpublished-require */
+
+  // We emulate Vercel so that we can set target to serverless if needed
+  process.env.NOW_BUILDER = true
+  // If no valid target is set, we use an internal Next env var to force it
+  process.env.NEXT_PRIVATE_TARGET = 'serverless'
+
+  // 🐉 We need Next to recalculate "isZeitNow" var so we can set the target, but it's
+  // set as an import side effect so we need to clear the require cache first. 🐲
+  // https://github.com/vercel/next.js/blob/canary/packages/next/telemetry/ci-info.ts
+
+  delete require.cache[require.resolve('next/dist/telemetry/ci-info')]
+  delete require.cache[require.resolve('next/dist/next-server/server/config')]
+
+  // Clear memoized cache
+  getNextConfig.clear()
+
+  /* eslint-enable fp/no-delete, node/no-unpublished-require */
+}
+
+module.exports = verifyBuildTarget

index.js

@@ -1,19 +1,13 @@
-const fs = require('fs')
-const path = require('path')
-const util = require('util')
-
-const findUp = require('find-up')
 const makeDir = require('make-dir')
 
 const { restoreCache, saveCache } = require('./helpers/cacheBuild')
 const copyUnstableIncludedDirs = require('./helpers/copyUnstableIncludedDirs')
 const doesNotNeedPlugin = require('./helpers/doesNotNeedPlugin')
 const getNextConfig = require('./helpers/getNextConfig')
 const validateNextUsage = require('./helpers/validateNextUsage')
+const verifyBuildTarget = require('./helpers/verifyBuildTarget')
 const nextOnNetlify = require('./src/index.js')
 
-const pWriteFile = util.promisify(fs.writeFile)
-
 // * Helpful Plugin Context *
 // - Between the prebuild and build steps, the project's build command is run
 // - Between the build and postbuild steps, any functions are bundled
@@ -29,21 +23,13 @@ module.exports = {
       return failBuild('Could not find a package.json for this project')
     }
 
-    const pluginNotNeeded = await doesNotNeedPlugin({ netlifyConfig, packageJson, failBuild })
-
-    if (!pluginNotNeeded) {
-      const nextConfigPath = await findUp('next.config.js')
-      if (nextConfigPath === undefined) {
-        // Create the next config file with target set to serverless by default
-        const nextConfig = `
-            module.exports = {
-              target: 'serverless'
-            }
-          `
-        await pWriteFile('next.config.js', nextConfig)
-      }
+    if (doesNotNeedPlugin({ netlifyConfig, packageJson, failBuild })) {
+      return
     }
 
+    // Populates the correct config if needed
+    await verifyBuildTarget({ netlifyConfig, packageJson, failBuild })
+
     // Because we memoize nextConfig, we need to do this after the write file
     const nextConfig = await getNextConfig(utils.failBuild)
 
@@ -64,7 +50,7 @@ module.exports = {
   }) {
     const { failBuild } = utils.build
 
-    if (await doesNotNeedPlugin({ netlifyConfig, packageJson, failBuild })) {
+    if (doesNotNeedPlugin({ netlifyConfig, packageJson, failBuild })) {
       return
     }
 
@@ -76,7 +62,7 @@ module.exports = {
   },
 
   async onPostBuild({ netlifyConfig, packageJson, constants: { FUNCTIONS_DIST }, utils }) {
-    if (await doesNotNeedPlugin({ netlifyConfig, packageJson, utils })) {
+    if (doesNotNeedPlugin({ netlifyConfig, packageJson, utils })) {
       return
     }
 

test/index.js

@@ -1,10 +1,12 @@
 const path = require('path')
 const process = require('process')
+
+const cpy = require('cpy')
 const pathExists = require('path-exists')
 const { dir: getTmpDir } = require('tmp-promise')
-const cpy = require('cpy')
 
 const plugin = require('..')
+const getNextConfig = require('../helpers/getNextConfig')
 
 const FIXTURES_DIR = `${__dirname}/fixtures`
 const SAMPLE_PROJECT_DIR = `${__dirname}/sample`
@@ -47,6 +49,11 @@ const useFixture = async function (fixtureName) {
 // In each test, we change cwd to a temporary directory.
 // This allows us not to have to mock filesystem operations.
 beforeEach(async () => {
+  delete process.env.NEXT_PRIVATE_TARGET
+  delete require.cache[require.resolve('next/dist/telemetry/ci-info')]
+  delete require.cache[require.resolve('next/dist/next-server/server/config')]
+
+  getNextConfig.clear()
   const { path, cleanup } = await getTmpDir({ unsafeCleanup: true })
   const restoreCwd = changeCwd(path)
   Object.assign(this, { cleanup, restoreCwd })
@@ -66,17 +73,6 @@ const DUMMY_PACKAGE_JSON = { name: 'dummy', version: '1.0.0' }
 const netlifyConfig = { build: {} }
 
 describe('preBuild()', () => {
-  test('create next.config.js with correct target if file does not exist', async () => {
-    await plugin.onPreBuild({
-      netlifyConfig,
-      packageJson: DUMMY_PACKAGE_JSON,
-      utils,
-      constants: { FUNCTIONS_SRC: 'out_functions' },
-    })
-
-    expect(await pathExists('next.config.js')).toBeTruthy()
-  })
-
   test('do nothing if the app has static html export in npm script', async () => {
     await plugin.onPreBuild({
       netlifyConfig: { build: { command: 'npm run build' } },
@@ -89,14 +85,15 @@ describe('preBuild()', () => {
   })
 
   test('run plugin if the app has next export in an unused script', async () => {
+    process.env.hi = 'ok'
     await plugin.onPreBuild({
       netlifyConfig,
       packageJson: { ...DUMMY_PACKAGE_JSON, scripts: { export: 'next export' } },
       utils,
       constants: {},
     })
-
-    expect(await pathExists('next.config.js')).toBeTruthy()
+    expect(process.env.NEXT_PRIVATE_TARGET).toBe('serverless')
+    // expect(await pathExists('next.config.js')).toBeTruthy()
   })
 
   test('do nothing if app has static html export in toml/ntl config', async () => {
@@ -107,7 +104,7 @@ describe('preBuild()', () => {
       constants: { FUNCTIONS_SRC: 'out_functions' },
     })
 
-    expect(await pathExists('next.config.js')).toBeFalsy()
+    expect(process.env.NEXT_PRIVATE_TARGET).toBeUndefined()
   })
 
   test('do nothing if app has next-on-netlify installed', async () => {
@@ -120,7 +117,7 @@ describe('preBuild()', () => {
       utils,
     })
 
-    expect(await pathExists('next.config.js')).toBeFalsy()
+    expect(process.env.NEXT_PRIVATE_TARGET).toBeUndefined()
   })
 
   test('do nothing if app has next-on-netlify postbuild script', async () => {
@@ -133,7 +130,7 @@ describe('preBuild()', () => {
       utils,
     })
 
-    expect(await pathExists('next.config.js')).toBeFalsy()
+    expect(process.env.NEXT_PRIVATE_TARGET).toBeUndefined()
   })
 
   test('fail build if the app has no package.json', async () => {
@@ -185,6 +182,7 @@ describe('preBuild()', () => {
 })
 
 describe('onBuild()', () => {
+  // eslint-disable-next-line max-lines
   test('does not run onBuild if using next-on-netlify', async () => {
     const packageJson = {
       scripts: { postbuild: 'next-on-netlify' },
@@ -202,23 +200,6 @@ describe('onBuild()', () => {
     expect(await pathExists(`${PUBLISH_DIR}/index.html`)).toBeFalsy()
   })
 
-  test.each(['invalid_next_config', 'deep_invalid_next_config'])(
-    `do nothing if the app's next config has an invalid target`,
-    async (fixtureName) => {
-      await useFixture(fixtureName)
-      const PUBLISH_DIR = 'publish'
-      await plugin.onBuild({
-        netlifyConfig,
-        packageJson: DUMMY_PACKAGE_JSON,
-        utils,
-        constants: { FUNCTIONS_SRC: 'out_functions' },
-        utils,
-      })
-
-      expect(await pathExists(`${PUBLISH_DIR}/index.html`)).toBeFalsy()
-    },
-  )
-
   test('copy files to the publish directory', async () => {
     await useFixture('publish_copy_files')
     await moveNextDist()