feat: auto remove middleware when A/B tests are stopping

src/manage-middleware.ts

@@ -0,0 +1,27 @@
+import { join } from 'path'
+import {
+  exploreUnmanagedMiddlewares,
+  installMiddleware,
+  removeMiddleware
+} from './utils-for-middleware'
+
+export const manageMiddleware = (
+  filePaths: string[],
+  prefix: string | undefined,
+  command: 'install' | 'remove'
+) => {
+  const joinedFilePaths = filePaths.map((p) => join(prefix ?? '', p))
+  joinedFilePaths.forEach((path) => {
+    if (command === 'install') installMiddleware(path)
+    if (command === 'remove') removeMiddleware(path)
+  })
+
+  exploreUnmanagedMiddlewares(
+    join(prefix ?? '', 'src', 'pages'),
+    command === 'remove' ? [] : joinedFilePaths
+  )
+  exploreUnmanagedMiddlewares(
+    join(prefix ?? '', 'pages'),
+    command === 'remove' ? [] : joinedFilePaths
+  )
+}

src/utils-for-middleware.ts

@@ -0,0 +1,76 @@
+import {
+  unlinkSync,
+  writeFileSync,
+  readFileSync,
+  readdirSync,
+  existsSync
+} from 'fs'
+import { resolve } from 'app-root-path'
+
+const DOC_LINK =
+  'https://github.com/aiji42/next-with-split/tree/main#auto-installremove-middleware-file'
+const LIBRARY_NAME = 'next-with-split'
+
+export const installMiddleware = (middlewarePath: string) => {
+  validateMiddlewarePath(middlewarePath)
+  const path = resolve(middlewarePath)
+  if (
+    existsSync(path) &&
+    !isNextWithSplitMiddleware(readFileSync(path).toString())
+  ) {
+    throw new Error(`Manually created middleware is present: ${middlewarePath}`)
+  }
+  console.log('split traffic enabled, installing middleware: ', middlewarePath)
+  writeFileSync(path, scriptText)
+}
+
+export const removeMiddleware = (middlewarePath: string) => {
+  validateMiddlewarePath(middlewarePath)
+  const path = resolve(middlewarePath)
+  if (existsSync(path)) {
+    console.log('split traffic disabled, removing middleware: ', middlewarePath)
+    unlinkSync(path)
+  }
+}
+
+export const exploreUnmanagedMiddlewares = (
+  rootDir: string,
+  excludes: string[]
+) => {
+  if (!existsSync(rootDir)) return
+  const middlewares = fileList(resolve(rootDir)).filter((path) =>
+    path.includes('_middleware')
+  )
+  const resolvedExcludes = excludes.map(resolve)
+
+  const unmanaged = middlewares.find((m) => {
+    return resolvedExcludes.some((e) => e === m)
+      ? false
+      : readFileSync(m).toString().includes(LIBRARY_NAME)
+  })
+  if (unmanaged)
+    throw new Error(
+      `There is middleware that is not managed by ${LIBRARY_NAME}; ${unmanaged}\nSee ${DOC_LINK}`
+    )
+}
+
+const fileList = (dir: string): string[] =>
+  readdirSync(dir, { withFileTypes: true }).flatMap((dirent) =>
+    dirent.isFile()
+      ? [`${dir}/${dirent.name}`]
+      : fileList(`${dir}/${dirent.name}`)
+  )
+
+const validateMiddlewarePath = (path: string) => {
+  if (!/_middleware\.(js|ts)$/.test(path))
+    throw new Error(`Invalid middleware path: ${path}`)
+}
+
+const isNextWithSplitMiddleware = (content: string): boolean =>
+  content.includes(LIBRARY_NAME)
+
+export const scriptText = `// This file was installed automatically by ${LIBRARY_NAME}.
+// Note: Do not update this file manually.
+// See ${DOC_LINK}
+export { middleware } from "${LIBRARY_NAME}"
+`

src/with-split.ts

@@ -2,14 +2,14 @@ import { SplitOptions } from './types'
 import { makeRuntimeConfig } from './make-runtime-config'
 import { NextConfig } from 'next/dist/server/config'
 import { ImageConfig } from 'next/dist/server/image-config'
-import { exec } from 'child_process'
+import { manageMiddleware } from './manage-middleware'
 
 type WithSplitArgs = {
   splits?: SplitOptions
   currentBranch?: string
   isOriginal?: boolean
   hostname?: string
-  middleware?: { manage?: boolean; paths?: string[] }
+  middleware?: { manage?: boolean; paths?: string[]; appRootDir?: string }
 }
 
 export const withSplit =
@@ -26,18 +26,24 @@ export const withSplit =
         : JSON.parse(process.env.SPLIT_CONFIG_BY_SPECTRUM ?? '{}')
 
     if (['true', '1'].includes(process.env.SPLIT_DISABLE ?? '')) {
-      middleware.manage && manageMiddleware(middleware.paths ?? [], 'remove')
+      middleware.manage &&
+        manageMiddleware(
+          middleware.paths ?? [],
+          middleware.appRootDir,
+          'remove'
+        )
       return nextConfig
     }
 
     const isMain =
       ['true', '1'].includes(process.env.SPLIT_ACTIVE ?? '') ||
       (manuals?.isOriginal ?? process.env.VERCEL_ENV === 'production')
+    const splitting = Object.keys(splits).length > 0 && isMain
     const assetHost = manuals?.hostname ?? process.env.VERCEL_URL
     const currentBranch =
       manuals?.currentBranch ?? process.env.VERCEL_GIT_COMMIT_REF ?? ''
 
-    if (Object.keys(splits).length > 0 && isMain) {
+    if (splitting) {
       console.log('Split tests are active.')
       console.table(
         Object.entries(splits).map(([testKey, options]) => {
@@ -55,7 +61,11 @@ export const withSplit =
     }
 
     middleware.manage &&
-      manageMiddleware(middleware.paths ?? [], isMain ? 'install' : 'remove')
+      manageMiddleware(
+        middleware.paths ?? [],
+        middleware.appRootDir,
+        splitting ? 'install' : 'remove'
+      )
 
     if (isSubjectedSplitTest(splits, currentBranch))
       process.env.NEXT_PUBLIC_IS_TARGET_SPLIT_TESTING = 'true'
@@ -93,18 +103,3 @@ const isSubjectedSplitTest = (
   )
   return branches.includes(currentBranch)
 }
-
-const manageMiddleware = (paths: string[], command: 'install' | 'remove') => {
-  paths.forEach((path) => {
-    exec(`npx next-with-split ${command} ${path}`, (err, stdout, stderr) => {
-      if (stdout) console.log(stdout)
-      if (err) {
-        if (stderr) throw new Error(stderr)
-        throw err
-      }
-      if (stderr) throw new Error(stderr)
-    })
-  })
-
-  // TODO: Explores the pages directory and alerts if there is middleware outside of its control.
-}