There is an established standard by which proxies are configured. It runs via the following environment variables:

• https_proxy: Proxy for https traffic
• http_proxy: Proxy for http traffic
• no_proxy: URLs that should not run via a proxy.

The native fetch client of NodeJS does not offer any functionality for this out-of-the-box, but there is an agent from the undici http client that you can use:

import { EnvHttpProxyAgent } from "undici";

const ENV_HTTP_PROXY_AGENT = new EnvHttpProxyAgent();
const proxyAgent = { dispatcher: ENV_HTTP_PROXY_AGENT } as any;

await fetch("https://...", {
  ...proxyAgent,
});

The node type definition does not support a dispatcher attribute for fetch, but it’s a supported logic. So if you’re using TypeScript you can ignore the error or use the beloved as any pattern for the proxy agent.

And that’s everything, no manual evaluation of the environment variables. Everything is handled by the EnvHttpProxyAgent from undici.