Example update proxy for electron

updateProxy.ts

import http from "http";
import https from "https";
import {
	AddressInfo,
} from "net";
import { URL } from "url";

const updateServer = "https://updates.yourserver.com/path/to/update/dir/without/trailing/slash";
const updateAuth = `Basic ${Buffer.from("username:password").toString("base64")}`

export function startUpdateProxy() {
	return new Promise<{ url: string; server: http.Server}>((res, rej) => {

		const server = http.createServer((request, response) => {
			const requestURL = new URL(updateServer + request.url);
			const endReq = https.request(requestURL, {
				headers: {
					...request.headers,
					Authorization: updateAuth,
					Host: requestURL.host,
				},
			}, (endRes) => {
				response.writeHead(endRes.statusCode || 500, endRes.headers);
				endRes.pipe(response);
				endRes.on("error", (err) => response.destroy(err));
			});
			request.pipe(endReq);
			endReq.on("error", (err) => response.writeHead(500, `${String(err)} when connecting to ${updateServer + request.url}`).end());
		});
		server.listen({
			host: "127.0.0.1",
			port: 0,
		});
		server.on("listening", () => {
			res({
				url: `http://127.0.0.1:${(server.address() as AddressInfo).port}`,
				server,
			});
		});
		server.on("error", rej);

	});
}

This code was inspired by this issue thread, and partly by the specific issue linked because I still wanted delta updates and didn't want to have to write my own manifest parser. Unfortunately, these requirements complicate matters quite a bit, so why not let Squirrel do the heavy lifting (that's what it was made for anyways, wasn't it?) and just intercept requests?

electron/electron#5020 (comment)