How you set proxying behaviour up depends on whether you are using fetch(), node-fetch or something else.

Approach 1 - Agnostic secondary proxy

This is I've found the simplest approach, and it has the advantage of not caring what http client you are using.

Simply run a service that looks like this:

//proxy.js

var http = require('http');
var httpProxy = require('http-proxy');

const {HttpsProxyAgent} = require('https-proxy-agent');

const agent = new HttpsProxyAgent("https://127.0.0.1:8080")   // The address of your target proxy

var proxy = httpProxy.createProxyServer({"agent": agent});

http.createServer(function(req, res) {
    proxy.web(
        req,
        res,
        {
            changeOrigin: true,
            target: 'http://jsonplaceholder.typicode.com'} // The address of upstream
    ); 
}).listen(3001);

And in your application where you were doing:

fetch('http://jsonplaceholder.typicode.com/posts'); 

//or 

nodeFetch('http://jsonplaceholder.typicode.com/posts'); 

//or

axios('http://jsonplaceholder.typicode.com/posts'); 

replace with:

fetch(`${process.env.UPSTREAM_URL}/posts`); 

//or 

nodeFetch(`${process.env.UPSTREAM_URL}posts`); 

//or

axios(`${process.env.UPSTREAM_URL}/posts`); 

Approach 2 - Proxying native fetch with undici ProxyAgent

Add this to the entrypoint of your application:

import { setGlobalDispatcher, ProxyAgent } from "undici";
const dispatcher = new ProxyAgent({uri: new URL("https://127.0.0.1:8080").toString() });
setGlobalDispatcher(dispatcher);

Done.

Approach 3 - Proxying node-fetch with https-proxy-agent

Modify your requests to include the proxy agent:

import {HttpsProxyAgent} from 'https-proxy-agent';

import nodeFetch from"node-fetch";

const agent = new HttpsProxyAgent("https://127.0.0.1:8080")

async function getData() {
    const result = await nodeFetch("https://jsonplaceholder.typicode.com/posts/6", {
        agent: agent
    })
    return result.json();
}

This has the disadvantage that you need to set the proxy agent on every request, so you may wish to expose your own wrapper fetch instead:

import nodeFetch from"node-fetch";

const agent = new HttpsProxyAgent("https://127.0.0.1:8080")

export const myNodeFetch: typeof nodeFetch = (url, options) => {

    if(options?.agent){
        console.warn("options.agent was provided to myNodeFetch, this will be clobbered!")
    }

    const newOptions = {
        ...(options ?? {}),
        agent
    };

    return nodeFetch(url, newOptions)
}

SSL/TSL Certificates for approaches #2 and #3

Your secure requests will remain using the secure protocol, and as such your application needs to trust your proxies certificates.

Using the NODE_EXTRA_CA_CERTS env var will work will work for both fetch() and node-fetch.

Questions? Comments? Criticisms? Get in the comments! 👇