https://rcoedo.com/blog/2019/07/08/tracing-express-services-with-zipkin-js

date-service-1.js

const express = require("express");

const app = express();
const port = process.env.PORT || 3001;

app.get("/time", (req, res) => {
  res.json({ currentDate: new Date().getTime() });
});

app.listen(port, () => console.log(`Date service listening on port ${port}`));

date-service-2.js

const express = require("express");

// Import zipkin stuff
const { Tracer, ExplicitContext, BatchRecorder, jsonEncoder } = require("zipkin");
const { HttpLogger } = require("zipkin-transport-http");
const zipkinMiddleware = require("zipkin-instrumentation-express").expressMiddleware;

const ZIPKIN_ENDPOINT = process.env.ZIPKIN_ENDPOINT || "http://localhost:9411";

// Get ourselves a zipkin tracer
const tracer = new Tracer({
  ctxImpl: new ExplicitContext(),
  recorder: new BatchRecorder({
    logger: new HttpLogger({
      endpoint: `${ZIPKIN_ENDPOINT}/api/v2/spans`,
      jsonEncoder: jsonEncoder.JSON_V2,
    }),
  }),
  localServiceName: "date-service",
});

const app = express();
const port = process.env.PORT || 3001;

// Add zipkin express middleware
app.use(zipkinMiddleware({ tracer }));

app.get("/time", (req, res) => {
  res.json({ currentDate: new Date().getTime() });
});

app.listen(port, () => console.log(`Date service listening on port ${port}`));

date-service-3.js

// Our date service controller will look like this
app.get("/time", async (req, res) => {
  await tracer.local("awaiting 200ms delay", () => delay(200));
  res.json({ currentDate: new Date().getTime() });
});

delay.js

// We can define a delay function with this one line
const delay = ms => new Promise(resolve => setTimeout(resolve, ms));

docker-compose.yml

version: "2"

services:
  storage:
    image: openzipkin/zipkin-mysql
    container_name: zipkin-playground-mysql
    environment:
      - MYSQL_HOST=mysql

  zipkin:
    image: openzipkin/zipkin
    container_name: zipkin-playground-zipkin
    environment:
      - STORAGE_TYPE=mysql
      - MYSQL_HOST=zipkin-playground-mysql
    ports:
      - 9411:9411
    depends_on:
      - storage

Examples for "Tracing Express Services with zipkin-js"

This gist contains the examples for the article "Tracing Express Services with zipkin-js".

- https://medium.com/trabe/tracing-express-services-with-zipkin-js-6e5c5680467e
- https://rcoedo.com/blog/2019/07/08/tracing-express-services-with-zipkin-js

views-index.pug

// This lives in views/index.pug
html
  head
    title= "What time is it?"
  body
    h1= date

web-service-1.js

const express = require("express");

// Import axios and axios instrumentation
const axios = require("axios");
const zipkinInstrumentationAxios = require("zipkin-instrumentation-axios");

// Import zipkin stuff
const { Tracer, ExplicitContext, BatchRecorder, jsonEncoder } = require("zipkin");
const { HttpLogger } = require("zipkin-transport-http");
const zipkinMiddleware = require("zipkin-instrumentation-express").expressMiddleware;

const ZIPKIN_ENDPOINT = process.env.ZIPKIN_ENDPOINT || "http://localhost:9411";
const API_ENDPOINT = process.env.API_ENDPOINT || "http://localhost:3001";

// Get ourselves a zipkin tracer
const tracer = new Tracer({
  ctxImpl: new ExplicitContext(),
  recorder: new BatchRecorder({
    logger: new HttpLogger({
      endpoint: `${ZIPKIN_ENDPOINT}/api/v2/spans`,
      jsonEncoder: jsonEncoder.JSON_V2,
    }),
  }),
  localServiceName: "web-service",
});

const app = express();
const port = process.env.PORT || 3000;

// Add zipkin express middleware
app.use(zipkinMiddleware({ tracer }));

// Add axios instrumentation
const zipkinAxios = zipkinInstrumentationAxios(axios, { tracer, serviceName: "axios-client" });

// We use pug to render the template
app.set("view engine", "pug");

app.get("/", async (req, res, next) => {
  try {
    const result = await zipkinAxios.get(`${API_ENDPOINT}/time`);
    res.render("index", { date: new Date(result.data.currentDate).toLocaleTimeString() });
  } catch (error) {
    next(error);
  }
});

app.listen(port, () => console.log(`Web service listening on port ${port}`));

web-service-2.js

// Our web service controller will look like this
app.get("/", async (req, res, next) => {
  try {
    await tracer.local("awaiting 100ms delay", () => delay(100));
    const result = await zipkinAxios.get(`${API_ENDPOINT}/time`);
    res.render("index", { date: new Date(result.data.currentDate).toLocaleTimeString() });
  } catch (error) {
    next(error);
  }
});