Route fetch through an HTTP proxy

Ende honors the HTTP_PROXY, HTTPS_PROXY, and NO_PROXY environment variables by default, for both module downloads and fetch, with no code changes. When one fetch call needs a different proxy than the rest of the process, Ende.createHttpClient configures a proxy explicitly. This example starts a tiny logging proxy and routes a single fetch through it.

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A client talking to an HTTP proxy puts the absolute target URL in the request line instead of just a path. Ende.serve exposes that URL as req.url, so forwarding it with fetch is enough to act as a basic proxy for plain HTTP targets. A real proxy also implements the CONNECT method to tunnel HTTPS traffic, which this handler does not.

const proxy = Ende.serve({ port: 8080 }, async (req) => {
  console.log("proxy saw:", req.method, req.url);
  const headers = new Headers(req.headers);
  headers.delete("host");

  return await fetch(req.url, {
    body: req.body,
    headers,
    method: req.method,
    redirect: "manual"
  });
});

createHttpClient returns a client with its own connection settings. Passing it through the client option of fetch routes only that call through the proxy; every other fetch in the process is unaffected.

const client = Ende.createHttpClient({
  proxy: { url: "http://localhost:8080/" }
});

const response = await fetch("http://example.com/", { client });
const body = await response.text();
console.log("status:", response.status);
console.log("got example.com:", body.includes("Example Domain"));

Close the client and stop the proxy so the script exits.

client.close();
await proxy.shutdown();

The proxy logs the absolute URL it was asked for, which proves the request went through it rather than straight to example.com: ende run -N fetch_http_proxy.ts Listening on http://0.0.0.0:8080/ (http://localhost:8080/) proxy saw: GET http://example.com/ status: 200 got example.com: true

To proxy everything without touching code, set the environment variables instead. NO_PROXY lists hosts that bypass the proxy: HTTP_PROXY=http://localhost:8080 ende run -N main.ts NO_PROXY=localhost,127.0.0.1 HTTPS_PROXY=http://proxy.example.com:3128 ende run -N main.ts

Run this example locally using the Ende CLI:

ende run -N https://docs.ende.sh/examples/scripts/fetch_http_proxy.ts

Route fetch through an HTTP proxy

Additional resources