Merge pull request #408 from netlify/mk/force-serverless

fix: force serverless target

Author: ascorbic

demo/next.config.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/doesNotNeedPlugin.js

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

helpers/getNextConfig.js

@@ -0,0 +1,58 @@
+const getNextConfig = require('./getNextConfig')
+const findUp = require('find-up')
+const { writeFile, unlink } = require('fs-extra')
+const path = require('path')
+
+// 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+  /* eslint-disable fp/no-delete, node/no-unpublished-require */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()
+
+  // Creating a config file, because otherwise Next won't reload the config and pick up the new target
+
+  if (!(await findUp('next.config.js'))) {
+    await writeFile(
+      path.resolve('next.config.js'),
+      `module.exports = {
+  // Supported targets are "serverless" and "experimental-serverless-trace"
+  target: "serverless"
+}`,
+    )
+  }
+  // Force the new config to be generated
+  await getNextConfig(failBuild)
+
+  // Reset the value in case something else is looking for it
+  process.env.NOW_BUILDER = false
+  /* eslint-enable fp/no-delete, node/no-unpublished-require */
+}
+
+module.exports = verifyBuildTarget

helpers/hasCorrectNextConfig.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')
 
-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
     }