index.js

"use strict";
// Import tracing before any other package is imported.
require("./tracing.js");
const express = require("express");
const opentelemetry = require("@opentelemetry/api");
const tracer = opentelemetry.trace.getTracer("example-basic-tracer-node");

// App
const app = express();
app.get("/", async (req, res) => {
  const firstSpan = tracer.startSpan("start");
  firstSpan.setAttribute("number", 1);
  const result = firstSpan.end(); // and they set the result

  for (let i = 0; i < 10; i += 1) {
    tracer.startActiveSpan("main", (span) => {
      for (let k = 0; k < 10; k += 1) {
        doWork();
      }

      // Be sure to end the span!
      span.end();
    });
  }

  function doWork() {
    // simulate some random work.
    for (let j = 0; j <= Math.floor(Math.random() * 40000000); j += 1) {
      // empty
      //console.log("DoWork")
    }
  }

  res.send("Hello World");
});

// Run API.
app.listen(process.env.PORT || 3000, () => console.log("Listening on port 3000."));