hello.js

const assert = require("assert");
const { initTracer } = require("../../lib/tracing");

const tracer = initTracer("hello-world");

const sayHello = helloTo => {
  const span = tracer.startSpan("say-hello");
  const ctx = { span };
  span.setTag("hello-to", helloTo);
  const helloStr = formatString(ctx, helloTo);
  printHello(ctx, helloStr);
  span.finish();
};

const formatString = (ctx, helloTo) => {
  ctx = {
    span: tracer.startSpan("formatString", { childOf: ctx.span }),
  };
  const helloStr = `Hello, ${helloTo}!`;
  ctx.span.log({
    event: "string-format",
    value: helloStr,
  });
  ctx.span.finish();
  return helloStr;
};

const printHello = (ctx, helloStr) => {
  ctx = {
    span: tracer.startSpan("printHello", { childOf: ctx.span }),
  };
  console.log(helloStr);
  ctx.span.log({ event: "print-string" });
  ctx.span.finish();
};

assert(process.argv.length == 3, "Expecting one argument");
const helloTo = process.argv[2];

sayHello(helloTo);

tracer.close(() => process.exit());