feat: use netlify:import-map specifier (#246)

* feat: use `netlify:import-map` specifier

* refactor: conditionally set import map URL

deno/bundle.ts

@@ -1,6 +1,6 @@
 import { writeStage2 } from './lib/stage2.ts'
 
 const [payload] = Deno.args
-const { basePath, destPath, externals, functions, importMapURL } = JSON.parse(payload)
+const { basePath, destPath, externals, functions, importMapData } = JSON.parse(payload)
 
-await writeStage2({ basePath, destPath, externals, functions, importMapURL })
+await writeStage2({ basePath, destPath, externals, functions, importMapData })

deno/lib/stage2.ts

@@ -3,7 +3,7 @@ import { build, LoadResponse } from 'https://deno.land/x/eszip@v0.28.0/mod.ts'
 import * as path from 'https://deno.land/std@0.127.0/path/mod.ts'
 
 import type { InputFunction, WriteStage2Options } from '../../shared/stage2.ts'
-import { virtualRoot } from '../../shared/consts.ts'
+import { importMapSpecifier, virtualRoot } from '../../shared/consts.ts'
 import { PUBLIC_SPECIFIER, STAGE2_SPECIFIER } from './consts.ts'
 import { inlineModule, loadFromVirtualRoot, loadWithRetry } from './common.ts'
 
@@ -63,14 +63,18 @@ const getVirtualPath = (basePath: string, filePath: string) => {
   return url
 }
 
-const stage2Loader = (basePath: string, functions: InputFunction[], externals: Set<string>) => {
+const stage2Loader = (basePath: string, functions: InputFunction[], externals: Set<string>, importMapData?: string) => {
   return async (specifier: string): Promise<LoadResponse | undefined> => {
     if (specifier === STAGE2_SPECIFIER) {
       const stage2Entry = getStage2Entry(basePath, functions)
 
       return inlineModule(specifier, stage2Entry)
     }
 
+    if (specifier === importMapSpecifier && importMapData !== undefined) {
+      return inlineModule(specifier, importMapData)
+    }
+
     if (specifier === PUBLIC_SPECIFIER || externals.has(specifier)) {
       return {
         kind: 'external',
@@ -86,8 +90,9 @@ const stage2Loader = (basePath: string, functions: InputFunction[], externals: S
   }
 }
 
-const writeStage2 = async ({ basePath, destPath, externals, functions, importMapURL }: WriteStage2Options) => {
-  const loader = stage2Loader(basePath, functions, new Set(externals))
+const writeStage2 = async ({ basePath, destPath, externals, functions, importMapData }: WriteStage2Options) => {
+  const importMapURL = importMapData ? importMapSpecifier : undefined
+  const loader = stage2Loader(basePath, functions, new Set(externals), importMapData)
   const bytes = await build([STAGE2_SPECIFIER], loader, importMapURL)
   const directory = path.dirname(destPath)
 

node/bundle.ts

@@ -7,5 +7,4 @@ export interface Bundle {
   extension: string
   format: BundleFormat
   hash: string
-  importMapURL?: string
 }

node/bundler.test.ts

@@ -1,12 +1,12 @@
 import { promises as fs } from 'fs'
 import { join, resolve } from 'path'
 import process from 'process'
-import { pathToFileURL } from 'url'
 
 import { deleteAsync } from 'del'
 import tmp from 'tmp-promise'
 import { test, expect } from 'vitest'
 
+import { importMapSpecifier } from '../shared/consts.js'
 import { useFixture } from '../test/util.js'
 
 import { BundleError } from './bundle_error.js'
@@ -30,9 +30,7 @@ test('Produces an ESZIP bundle', async () => {
   const generatedFiles = await fs.readdir(distPath)
 
   expect(result.functions.length).toBe(1)
-
-  // ESZIP, manifest and import map.
-  expect(generatedFiles.length).toBe(3)
+  expect(generatedFiles.length).toBe(2)
 
   const manifestFile = await fs.readFile(resolve(distPath, 'manifest.json'), 'utf8')
   const manifest = JSON.parse(manifestFile)
@@ -43,7 +41,7 @@ test('Produces an ESZIP bundle', async () => {
   expect(bundles[0].format).toBe('eszip2')
   expect(generatedFiles.includes(bundles[0].asset)).toBe(true)
 
-  expect(importMapURL).toBe('file:///root/.netlify/edge-functions-dist/import_map.json')
+  expect(importMapURL).toBe(importMapSpecifier)
 
   await cleanup()
 })
@@ -64,9 +62,7 @@ test('Uses the vendored eszip module instead of fetching it from deno.land', asy
   const generatedFiles = await fs.readdir(distPath)
 
   expect(result.functions.length).toBe(1)
-
-  // ESZIP, manifest and import map.
-  expect(generatedFiles.length).toBe(3)
+  expect(generatedFiles.length).toBe(2)
 
   const manifestFile = await fs.readFile(resolve(distPath, 'manifest.json'), 'utf8')
   const manifest = JSON.parse(manifestFile)
@@ -165,9 +161,7 @@ test('Uses the cache directory as the `DENO_DIR` value if the `edge_functions_ca
   const outFiles1 = await fs.readdir(distPath)
 
   expect(result1.functions.length).toBe(1)
-
-  // ESZIP, manifest and import map.
-  expect(outFiles1.length).toBe(3)
+  expect(outFiles1.length).toBe(2)
 
   try {
     await fs.readdir(join(cacheDir.path, 'deno_dir'))
@@ -185,9 +179,7 @@ test('Uses the cache directory as the `DENO_DIR` value if the `edge_functions_ca
   const outFiles2 = await fs.readdir(distPath)
 
   expect(result2.functions.length).toBe(1)
-
-  // ESZIP, manifest and import map.
-  expect(outFiles2.length).toBe(3)
+  expect(outFiles2.length).toBe(2)
 
   const denoDir2 = await fs.readdir(join(cacheDir.path, 'deno_dir'))
 
@@ -212,9 +204,7 @@ test('Supports import maps with relative paths', async () => {
   const generatedFiles = await fs.readdir(distPath)
 
   expect(result.functions.length).toBe(1)
-
-  // ESZIP, manifest and import map.
-  expect(generatedFiles.length).toBe(3)
+  expect(generatedFiles.length).toBe(2)
 
   const manifestFile = await fs.readFile(resolve(distPath, 'manifest.json'), 'utf8')
   const manifest = JSON.parse(manifestFile)
@@ -299,9 +289,7 @@ test('Processes a function that imports a custom layer', async () => {
   const generatedFiles = await fs.readdir(distPath)
 
   expect(result.functions.length).toBe(1)
-
-  // ESZIP, manifest and import map.
-  expect(generatedFiles.length).toBe(3)
+  expect(generatedFiles.length).toBe(2)
 
   const manifestFile = await fs.readFile(resolve(distPath, 'manifest.json'), 'utf8')
   const manifest = JSON.parse(manifestFile)
@@ -332,9 +320,7 @@ test('Loads declarations and import maps from the deploy configuration', async (
   const generatedFiles = await fs.readdir(distPath)
 
   expect(result.functions.length).toBe(2)
-
-  // ESZIP, manifest and import map.
-  expect(generatedFiles.length).toBe(3)
+  expect(generatedFiles.length).toBe(2)
 
   const manifestFile = await fs.readFile(resolve(distPath, 'manifest.json'), 'utf8')
   const manifest = JSON.parse(manifestFile)
@@ -346,40 +332,3 @@ test('Loads declarations and import maps from the deploy configuration', async (
 
   await cleanup()
 })
-
-test('Uses an absolute URL for the import map when the dist directory is not a child of the base path', async () => {
-  const { basePath, cleanup } = await useFixture('with_import_maps')
-  const { path: distPath } = await tmp.dir()
-  const declarations = [
-    {
-      function: 'func1',
-      path: '/func1',
-    },
-  ]
-  const sourceDirectory = join(basePath, 'functions')
-  const result = await bundle([sourceDirectory], distPath, declarations, {
-    basePath,
-    configPath: join(sourceDirectory, 'config.json'),
-  })
-  const generatedFiles = await fs.readdir(distPath)
-
-  expect(result.functions.length).toBe(1)
-
-  // ESZIP, manifest and import map.
-  expect(generatedFiles.length).toBe(3)
-
-  const manifestFile = await fs.readFile(resolve(distPath, 'manifest.json'), 'utf8')
-  const manifest = JSON.parse(manifestFile)
-  expect(() => validateManifest(manifest)).not.toThrowError()
-  const { bundles, import_map: importMapURL } = manifest
-
-  expect(bundles.length).toBe(1)
-  expect(bundles[0].format).toBe('eszip2')
-  expect(generatedFiles.includes(bundles[0].asset)).toBe(true)
-
-  const importMapPath = join(distPath, 'import_map.json')
-  expect(importMapURL).toBe(pathToFileURL(importMapPath).toString())
-
-  await cleanup()
-  await fs.rm(distPath, { recursive: true })
-})

node/bundler.ts

@@ -4,6 +4,8 @@ import { join } from 'path'
 import commonPathPrefix from 'common-path-prefix'
 import { v4 as uuidv4 } from 'uuid'
 
+import { importMapSpecifier } from '../shared/consts.js'
+
 import { DenoBridge, DenoOptions, OnAfterDownloadHook, OnBeforeDownloadHook } from './bridge.js'
 import type { Bundle } from './bundle.js'
 import { FunctionConfig, getFunctionConfig } from './config.js'
@@ -126,7 +128,7 @@ const bundle = async (
     declarations,
     distDirectory,
     functions,
-    importMapURL: functionBundle.importMapURL,
+    importMap: importMapSpecifier,
     layers: deployConfig.layers,
   })
 

node/config.test.ts

@@ -158,9 +158,7 @@ test('Ignores function paths from the in-source `config` function if the feature
   const generatedFiles = await fs.readdir(distPath)
 
   expect(result.functions.length).toBe(6)
-
-  // ESZIP, manifest and import map.
-  expect(generatedFiles.length).toBe(3)
+  expect(generatedFiles.length).toBe(2)
 
   const manifestFile = await fs.readFile(resolve(distPath, 'manifest.json'), 'utf8')
   const manifest = JSON.parse(manifestFile)
@@ -198,9 +196,7 @@ test('Loads function paths from the in-source `config` function', async () => {
   const generatedFiles = await fs.readdir(distPath)
 
   expect(result.functions.length).toBe(6)
-
-  // ESZIP, manifest and import map.
-  expect(generatedFiles.length).toBe(3)
+  expect(generatedFiles.length).toBe(2)
 
   const manifestFile = await fs.readFile(resolve(distPath, 'manifest.json'), 'utf8')
   const manifest = JSON.parse(manifestFile)

node/formats/eszip.ts

@@ -1,5 +1,4 @@
-import { join, relative } from 'path'
-import { pathToFileURL } from 'url'
+import { join } from 'path'
 
 import { virtualRoot } from '../../shared/consts.js'
 import type { WriteStage2Options } from '../../shared/stage2.js'
@@ -38,13 +37,13 @@ const bundleESZIP = async ({
   const extension = '.eszip'
   const destPath = join(distDirectory, `${buildID}${extension}`)
   const { bundler, importMap: bundlerImportMap } = getESZIPPaths()
-  const importMapURL = await createUserImportMap(importMap, basePath, distDirectory)
+  const importMapData = JSON.stringify(importMap.getContents(basePath, virtualRoot))
   const payload: WriteStage2Options = {
     basePath,
     destPath,
     externals,
     functions,
-    importMapURL,
+    importMapData,
   }
   const flags = ['--allow-all', '--no-config', `--import-map=${bundlerImportMap}`]
 
@@ -60,30 +59,7 @@ const bundleESZIP = async ({
 
   const hash = await getFileHash(destPath)
 
-  return { extension, format: BundleFormat.ESZIP2, hash, importMapURL }
-}
-
-// Takes an import map, writes it to a file on disk, and gets its URL relative
-// to the ESZIP root (i.e. using the virtual root prefix).
-const createUserImportMap = async (importMap: ImportMap, basePath: string, distDirectory: string) => {
-  const destPath = join(distDirectory, 'import_map.json')
-
-  await importMap.writeToFile(destPath)
-
-  const virtualPath = relative(basePath, destPath)
-
-  // If the dist directory is not a child of the base path, we can't represent
-  // the relative path as a file URL (because something like 'file://../foo' is
-  // not valid). This should never happen, but it's best to leave the absolute
-  // path untransformed to avoid getting a build error due to a missing import
-  // map.
-  if (virtualPath.startsWith('..')) {
-    return pathToFileURL(destPath).toString()
-  }
-
-  const importMapURL = new URL(virtualPath, virtualRoot)
-
-  return importMapURL.toString()
+  return { extension, format: BundleFormat.ESZIP2, hash }
 }
 
 const getESZIPPaths = () => {

node/import_map.test.ts

@@ -22,14 +22,14 @@ test('Handles import maps with full URLs without specifying a base URL', () => {
   }
 
   const map = new ImportMap([inputFile1, inputFile2])
-  const { imports } = JSON.parse(map.getContents())
+  const { imports } = map.getContents()
 
   expect(imports['netlify:edge']).toBe('https://edge.netlify.com/v1/index.ts')
   expect(imports['alias:jamstack']).toBe('https://jamstack.org/')
   expect(imports['alias:pets']).toBe('https://petsofnetlify.com/')
 })
 
-test('Resolves relative paths to absolute paths if a root path is not provided', () => {
+test('Resolves relative paths to absolute paths if a base path is not provided', () => {
   const basePath = join(cwd(), 'my-cool-site', 'import-map.json')
   const inputFile1 = {
     baseURL: pathToFileURL(basePath),
@@ -39,14 +39,14 @@ test('Resolves relative paths to absolute paths if a root path is not provided',
   }
 
   const map = new ImportMap([inputFile1])
-  const { imports } = JSON.parse(map.getContents())
+  const { imports } = map.getContents()
   const expectedPath = join(cwd(), 'my-cool-site', 'heart', 'pets')
 
   expect(imports['netlify:edge']).toBe('https://edge.netlify.com/v1/index.ts')
   expect(imports['alias:pets']).toBe(`${pathToFileURL(expectedPath).toString()}/`)
 })
 
-test('Transforms relative paths so that they use the root path as a base', () => {
+test('Transforms relative paths so that they become relative to the base path', () => {
   const basePath = join(cwd(), 'my-cool-site', 'import-map.json')
   const inputFile1 = {
     baseURL: pathToFileURL(basePath),
@@ -55,9 +55,33 @@ test('Transforms relative paths so that they use the root path as a base', () =>
     },
   }
 
+  // Without a prefix.
+  const map1 = new ImportMap([inputFile1])
+  const { imports: imports1 } = map1.getContents(cwd())
+
+  expect(imports1['netlify:edge']).toBe('https://edge.netlify.com/v1/index.ts')
+  expect(imports1['alias:pets']).toBe('file:///my-cool-site/heart/pets/')
+
+  // With a prefix.
+  const map2 = new ImportMap([inputFile1])
+  const { imports: imports2 } = map2.getContents(cwd(), 'file:///root/')
+
+  expect(imports2['netlify:edge']).toBe('https://edge.netlify.com/v1/index.ts')
+  expect(imports2['alias:pets']).toBe('file:///root/my-cool-site/heart/pets/')
+})
+
+test('Throws when an import map uses a relative path to reference a file outside of the base path', () => {
+  const basePath = join(cwd(), 'my-cool-site')
+  const inputFile1 = {
+    baseURL: pathToFileURL(join(basePath, 'import_map.json')),
+    imports: {
+      'alias:file': '../file.js',
+    },
+  }
+
   const map = new ImportMap([inputFile1])
-  const { imports } = JSON.parse(map.getContents(cwd()))
 
-  expect(imports['netlify:edge']).toBe('https://edge.netlify.com/v1/index.ts')
-  expect(imports['alias:pets']).toBe('./my-cool-site/heart/pets')
+  expect(() => map.getContents(basePath)).toThrowError(
+    `Import map cannot reference '${join(cwd(), 'file.js')}' as it's outside of the base directory '${basePath}'`,
+  )
 })