app.ts

import * as express from "express";
import axios from "axios";

const PORT: string = process.env.PORT || "8080";

import { countAllRequests } from './monitoring';
const app = express();
app.use(countAllRequests());

app.get("/", (req, res) => {
  axios
    .get(`http://localhost:${PORT}/middle-tier`)
    .then(() => axios.get(`http://localhost:${PORT}/middle-tier`))
    .then(result => {
      res.send(result.data);
    })
    .catch(err => {
      console.error(err);
      res.status(500).send();
    });
});

app.get("/middle-tier", (req, res) => {
  axios
    .get(`http://localhost:${PORT}/backend`)
    .then(() => axios.get(`http://localhost:${PORT}/backend`))
    .then(result => {
      res.send(result.data);
    })
    .catch(err => {
      console.error(err);
      res.status(500).send();
    });
});

app.get("/backend", (req, res) => {
  res.send("Hello from the backend");
});

app.listen(parseInt(PORT, 10), () => {
  console.log(`Listening for requests on http://localhost:${PORT}`);
});