cypress/scripts/binary/binary-cleanup.js

const fs = require('fs-extra')
const path = require('path')
const { consolidateDeps, getSnapshotCacheDir } = require('@tooling/v8-snapshot')
const del = require('del')
const esbuild = require('esbuild')
const tempDir = require('temp-dir')
const workingDir = path.join(tempDir, 'binary-cleanup-workdir')

fs.ensureDirSync(workingDir)

async function removeEmptyDirectories (directory) {
  // lstat does not follow symlinks (in contrast to stat)
  const fileStats = await fs.lstat(directory)

  if (!fileStats.isDirectory()) {
    return
  }

  let fileNames = await fs.readdir(directory)

  if (fileNames.length > 0) {
    const recursiveRemovalPromises = fileNames.map(
      (fileName) => removeEmptyDirectories(path.join(directory, fileName)),
    )

    await Promise.all(recursiveRemovalPromises)

    // re-evaluate fileNames; after deleting subdirectory
    // we may have parent directory empty now
    fileNames = await fs.readdir(directory)
  }

  if (fileNames.length === 0) {
    await fs.rmdir(directory)
  }
}

const getDependencyPathsToKeep = async (buildAppDir) => {
  const unixBuildAppDir = buildAppDir.split(path.sep).join(path.posix.sep)
  const startingEntryPoints = [
    'packages/server/lib/plugins/child/require_async_child.js',
    'packages/server/lib/plugins/child/register_ts_node.js',
    'packages/server/node_modules/@cypress/webpack-batteries-included-preprocessor/index.js',
    'packages/server/node_modules/ts-loader/index.js',
    'packages/rewriter/lib/threads/worker.js',
    'npm/webpack-batteries-included-preprocessor/index.js',
    'node_modules/find-up/index.js',
    'node_modules/webpack/lib/webpack.js',
    'node_modules/webpack-dev-server/lib/Server.js',
    'node_modules/html-webpack-plugin-4/index.js',
    'node_modules/html-webpack-plugin-5/index.js',
    'node_modules/mocha-7.0.1/index.js',
    'packages/server/node_modules/webdriver/build/index.js',
  ]

  let entryPoints = new Set([
    ...startingEntryPoints.map((entryPoint) => path.join(unixBuildAppDir, entryPoint)),
  ])
  let esbuildResult
  let newEntryPointsFound = true

  // The general idea here is to run esbuild on entry points that are used outside of the snapshot. If, during the process,
  // we find places where we do a require.resolve on a module, that should be treated as an additional entry point and we run
  // esbuild again. We do this until we no longer find any new entry points. The resulting metafile inputs are
  // the dependency paths that we need to ensure stay in the snapshot.
  while (newEntryPointsFound) {
    esbuildResult = await esbuild.build({
      entryPoints: [...entryPoints],
      bundle: true,
      outdir: workingDir,
      platform: 'node',
      metafile: true,
      absWorkingDir: unixBuildAppDir,
      external: [
        './transpile-ts',
        './start-cypress',
        'fsevents',
        'pnpapi',
        '@swc/core',
        'emitter',
        'ts-loader',
        'uglify-js',
        'esbuild',
        'enhanced-resolve/lib/createInnerCallback',
        '@babel/preset-typescript/package.json',
        './addon/addon-native',
      ],
    })

    newEntryPointsFound = false
    esbuildResult.warnings.forEach((warning) => {
      const matches = warning.text.match(/"(.*)" should be marked as external for use with "require.resolve"/)
      const warningSubject = matches && matches[1]

      if (warningSubject) {
        let entryPoint

        if (warningSubject.startsWith('.')) {
          entryPoint = path.join(unixBuildAppDir, path.dirname(warning.location.file), warningSubject)
        } else {
          entryPoint = require.resolve(warningSubject, { paths: [path.join(unixBuildAppDir, path.dirname(warning.location.file))] })
        }

        if (path.extname(entryPoint) !== '' && !entryPoints.has(entryPoint)) {
          newEntryPointsFound = true
          entryPoints.add(entryPoint)
        }
      }
    })
  }

  return [...Object.keys(esbuildResult.metafile.inputs), ...entryPoints, 'package.json']
}

const createServerEntryPointBundle = async (buildAppDir) => {
  const unixBuildAppDir = buildAppDir.split(path.sep).join(path.posix.sep)
  const entryPoints = [path.join(unixBuildAppDir, 'packages/server/index.js')]
  // Build the binary entry point ignoring anything that happens in start-cypress since that will be in the v8 snapshot
  const esbuildResult = await esbuild.build({
    entryPoints,
    bundle: true,
    outdir: workingDir,
    platform: 'node',
    metafile: true,
    absWorkingDir: unixBuildAppDir,
    external: [
      './transpile-ts',
      './start-cypress',
    ],
  })

  console.log(`copying server entry point bundle from ${path.join(workingDir, 'index.js')} to ${path.join(buildAppDir, 'packages', 'server', 'index.js')}`)

  await fs.copy(path.join(workingDir, 'index.js'), path.join(buildAppDir, 'packages', 'server', 'index.js'))

  // Convert these inputs to a relative file path. Note that these paths are posix paths.
  return [...Object.keys(esbuildResult.metafile.inputs)].filter((input) => input !== 'packages/server/index.js').map((input) => `./${input}`)
}

const buildEntryPointAndCleanup = async (buildAppDir) => {
  const [keptDependencies, serverEntryPointBundleDependencies] = await Promise.all([
    // 1. Retrieve all dependencies that still need to be kept in the binary. In theory, we could use the bundles generated here as single files within the binary,
    // but for now, we just track on the dependencies that get pulled in
    getDependencyPathsToKeep(buildAppDir),
    // 2. Create a bundle for the server entry point. This will be used to start the server in the binary. It returns the dependencies that are pulled in by this bundle that potentially can now be removed
    createServerEntryPointBundle(buildAppDir),
  ])

  // 3. Gather the dependencies that could potentially be removed from the binary due to being in the snapshot or in the entry point bundle
  const snapshotMetadata = require(path.join(getSnapshotCacheDir(), 'snapshot-meta.json'))
  const potentiallyRemovedDependencies = [
    ...snapshotMetadata.healthy,
    ...snapshotMetadata.deferred,
    ...snapshotMetadata.norewrite,
    ...serverEntryPointBundleDependencies,
  ]

  console.log(`potentially removing ${potentiallyRemovedDependencies.length} dependencies`)

  // 4. Remove all dependencies that are in the snapshot but not in the list of kept dependencies from the binary
  await Promise.all(potentiallyRemovedDependencies.map(async (dependency) => {
    const typeScriptlessDependency = dependency.replace(/\.ts$/, '.js')

    // babel/runtime requires all of its dependencies in a very non-standard dynamic way. We will keep anything in babel/runtime
    if (!keptDependencies.includes(typeScriptlessDependency.slice(2)) && !typeScriptlessDependency.includes('@babel/runtime')) {
      await fs.remove(path.join(buildAppDir, typeScriptlessDependency))
    }
  }))

  // 5. Consolidate dependencies that are safe to consolidate (`lodash` and `bluebird`)
  await consolidateDeps({ projectBaseDir: buildAppDir })
}

const cleanupUnneededDependencies = async (buildAppDir) => {
  console.log(`removing unnecessary files from the binary to further lean out the distribution.`)
  // 6. Remove various unnecessary files from the binary to further clean things up. Likely, there is additional work that can be done here
  // this is it's own function as we always want to clean out unneeded dependencies
  await del([
    // Remove test files
    path.join(buildAppDir, '**', 'test'),
    path.join(buildAppDir, '**', 'tests'),
    // What we need of prettier is entirely encapsulated within the v8 snapshot, but has a few leftover large files
    path.join(buildAppDir, '**', 'prettier', 'esm'),
    path.join(buildAppDir, '**', 'prettier', 'standalone.js'),
    path.join(buildAppDir, '**', 'prettier', 'bin-prettier.js'),
    // ESM files are mostly not needed currently
    path.join(buildAppDir, '**', '@babel', '**', 'esm'),
    path.join(buildAppDir, '**', 'ramda', 'es'),
    path.join(buildAppDir, '**', 'jimp', 'es'),
    path.join(buildAppDir, '**', 'nexus', 'dist-esm'),
    path.join(buildAppDir, '**', '@graphql-tools', '**', '*.mjs'),
    path.join(buildAppDir, '**', 'graphql', '**', '*.mjs'),
    path.join(buildAppDir, '**', '@openTelemetry', '**', 'esm'),
    path.join(buildAppDir, '**', '@openTelemetry', '**', 'esnext'),
    // We currently do not use any map files
    path.join(buildAppDir, '**', '*js.map'),
    // License files need to be kept
    path.join(buildAppDir, '**', '!(LICENSE|license|License).md'),
    // These are type related files that are not used within the binary
    path.join(buildAppDir, '**', '*.d.ts'),
    path.join(buildAppDir, '**', 'ajv', 'lib', '**', '*.ts'),
    path.join(buildAppDir, '**', '*.flow'),
    // Documentation files are not needed
    path.join(buildAppDir, '**', 'JSV', 'jsdoc-toolkit'),
    path.join(buildAppDir, '**', 'JSV', 'docs'),
    path.join(buildAppDir, '**', 'fluent-ffmpeg', 'doc'),
    // Files used as part of prebuilding are not necessary
    path.join(buildAppDir, '**', 'node_gyp_bins'),
    path.join(buildAppDir, '**', 'better-sqlite3', 'bin'),
    path.join(buildAppDir, '**', 'registry-js', 'prebuilds'),
    path.join(buildAppDir, '**', '*.cc'),
    path.join(buildAppDir, '**', '*.o'),
    path.join(buildAppDir, '**', '*.c'),
    path.join(buildAppDir, '**', '*.h'),
    // Remove distributions that are not needed in the binary
    path.join(buildAppDir, '**', 'ramda', 'dist'),
    path.join(buildAppDir, '**', 'jimp', 'browser'),
    path.join(buildAppDir, '**', '@jimp', '**', 'src'),
    path.join(buildAppDir, '**', 'nexus', 'src'),
    path.join(buildAppDir, '**', 'source-map', 'dist'),
    path.join(buildAppDir, '**', 'source-map-js', 'dist'),
    path.join(buildAppDir, '**', 'pako', 'dist'),
    path.join(buildAppDir, '**', 'node-forge', 'dist'),
    path.join(buildAppDir, '**', 'pngjs', 'browser.js'),
    path.join(buildAppDir, '**', 'plist', 'dist'),
    // Remove yarn locks
    path.join(buildAppDir, '**', 'yarn.lock'),
  ], { force: true })

  // 7. Remove any empty directories as a result of the rest of the cleanup
  await removeEmptyDirectories(buildAppDir)
}

module.exports = {
  buildEntryPointAndCleanup,
  cleanupUnneededDependencies,
}