Http proxy for fetch (#4676)

* Add HTTP Proxy Support to `fetch` Polyfill

Use `global-agent` to support HTTP_PROXY, HTTPS_PROXY, and NO_PROXY
environment variables.

* Add Changeset For HTTP Proxy Support in `fetch`

.changeset/curvy-needles-boil.md

@@ -0,0 +1,5 @@
+---
+'@astrojs/webapi': minor
+---
+
+Add HTTP Proxy Support to `fetch` Polyfill

packages/webapi/package.json

@@ -50,6 +50,7 @@
   "bugs": "https://github.com/withastro/astro/issues",
   "homepage": "https://github.com/withastro/astro/tree/main/packages/webapi#readme",
   "dependencies": {
+    "global-agent": "^3.0.0",
     "node-fetch": "^3.2.5"
   },
   "devDependencies": {
@@ -58,6 +59,7 @@
     "@rollup/plugin-node-resolve": "^13.3.0",
     "@rollup/plugin-typescript": "^8.3.2",
     "@types/chai": "^4.3.1",
+    "@types/global-agent": "^2.1.1",
     "@types/mocha": "^9.1.1",
     "@types/node": "^14.18.21",
     "@ungap/structured-clone": "^0.3.4",

packages/webapi/run/build.js

@@ -178,7 +178,7 @@ async function build() {
 			inputOptions: {
 				input: 'src/polyfill.ts',
 				plugins: plugins,
-				external: ['node-fetch'],
+				external: ['node-fetch', 'global-agent'],
 				onwarn(warning, warn) {
 					if (warning.code !== 'UNRESOLVED_IMPORT') warn(warning)
 				},

packages/webapi/src/lib/fetch.ts

@@ -2,6 +2,13 @@ import type { RequestInit } from 'node-fetch'
 import { default as nodeFetch, Headers, Request, Response } from 'node-fetch'
 import Stream from 'node:stream'
 import * as _ from './utils'
+import {
+	bootstrap as bootstrapGlobalAgent
+} from 'global-agent';
+
+bootstrapGlobalAgent({
+	environmentVariableNamespace: '',
+});
 
 export { Headers, Request, Response }