run.js

const express = require("express");
const proxy = require("http-proxy-middleware");
const path = require("path");

const BACKEND_URL = process.env.API_URL || "http://localhost:8080";

const app = express();

// As the react JS code is executed on the client side, we have to publicly expose the backend. One easy option is to do so via frontend, as this is exposed anyways.
app.use(
  "/api",
  proxy({
    target: BACKEND_URL,
    changeOrigin: true
  })
);

app.use(express.static(path.join(__dirname, "/build")));
app.get("/", (req, res) => {
  res.sendFile(path.join(__dirname + "/build/index.html"));
  console.log(__dirname + "/build/index.html");
});

app.listen(3000, () => {
  console.log("Server is running on port 3000");
});