feat: load bootstrap from deploy URL (#7)

* feat: load bootstrap from deploy URL

* feat: support loading boot URL from environment variable

.eslintrc.cjs

@@ -11,5 +11,14 @@ module.exports = {
   rules: {
     'node/no-missing-import': 'off',
   },
-  overrides: [...overrides],
+  overrides: [
+    ...overrides,
+    {
+      files: ['test/**/*.ts'],
+      rules: {
+        'max-statements': 'off',
+        'no-magic-numbers': 'off',
+      },
+    },
+  ],
 }

package.json

@@ -63,7 +63,7 @@
     "@commitlint/config-conventional": "^16.0.0",
     "@netlify/eslint-config-node": "^4.1.7",
     "@types/glob-to-regexp": "^0.4.1",
-    "@types/node": "^17.0.10",
+    "@types/node": "^17.0.21",
     "@types/semver": "^7.3.9",
     "@types/sinon": "^10.0.8",
     "@types/uuid": "^8.3.4",

src/bootstrap.ts

@@ -0,0 +1,8 @@
+import { env } from 'process'
+
+const BOOTSTRAP_LATEST =
+  'https://dinosaurs:are-the-future!@62337d29c8edd9000870ec20--edge-bootstrap.netlify.app/index.ts'
+
+const getBootstrapURL = () => env.NETLIFY_EDGE_BOOTSTRAP ?? BOOTSTRAP_LATEST
+
+export const getBootstrapImport = () => `import { boot } from "${getBootstrapURL()}";`

src/bundler.ts

@@ -5,6 +5,7 @@ import { pathToFileURL } from 'url'
 
 import { v4 as uuidv4 } from 'uuid'
 
+import { getBootstrapImport } from './bootstrap.js'
 import { DenoBridge, LifecycleHook } from './bridge.js'
 import type { BundleAlternate } from './bundle_alternate.js'
 import type { Declaration } from './declaration.js'
@@ -122,7 +123,7 @@ const createFinalBundles = async (bundleOps: Promise<string>[], distDirectory: s
 
 const generateEntrypoint = (handlers: Handler[], distDirectory: string) => {
   const lines = handlers.map((handler, index) => generateHandlerReference(handler, index, distDirectory))
-  const bootImport = 'import { boot } from "https://dinosaurs:are-the-future!@edge-bootstrap.netlify.app/index.ts";'
+  const bootImport = getBootstrapImport()
   const importLines = lines.map(({ importLine }) => importLine).join('\n')
   const exportLines = lines.map(({ exportLine }) => exportLine).join(', ')
   const exportDeclaration = `const handlers = {${exportLines}};`

test/bootstrap.ts

@@ -0,0 +1,63 @@
+import { Buffer } from 'buffer'
+import { env } from 'process'
+
+import test from 'ava'
+import fetch, { Headers } from 'node-fetch'
+
+import { getBootstrapImport } from '../src/bootstrap.js'
+
+const importURLRegex = /^import { boot } from "(.*)";$/m
+
+test.serial('Imports the bootstrap layer from a valid URL', async (t) => {
+  const importLine = getBootstrapImport()
+  const match = importLine.match(importURLRegex)
+  const url = match?.[1]
+
+  if (url === undefined) {
+    t.fail('Import expression is invalid')
+
+    return
+  }
+
+  const importURL = new URL(url)
+  const headers = new Headers()
+
+  // `node-fetch` doesn't let us send credentials as part of the URL, so we
+  // have to transform them into an `Authorization` header.
+  if (importURL.username) {
+    const auth = Buffer.from(`${importURL.username}:${importURL.password}`)
+
+    importURL.username = ''
+    importURL.password = ''
+
+    headers.set('Authorization', `Basic ${auth.toString('base64')}`)
+  }
+
+  const canonicalURL = importURL.toString()
+  const { status } = await fetch(canonicalURL, { headers })
+
+  t.is(status, 200)
+})
+
+test.serial(
+  'Imports the bootstrap layer from the URL present in the `NETLIFY_EDGE_BOOTSTRAP` environment variable, if present',
+  (t) => {
+    const mockURL = 'https://example.com/boot.ts'
+
+    env.NETLIFY_EDGE_BOOTSTRAP = mockURL
+
+    const importLine = getBootstrapImport()
+    const match = importLine.match(importURLRegex)
+    const url = match?.[1]
+
+    env.NETLIFY_EDGE_BOOTSTRAP = undefined
+
+    if (url === undefined) {
+      t.fail('Import expression is invalid')
+
+      return
+    }
+
+    t.is(url, mockURL)
+  },
+)