Zipkin distributed tracing between express.js based aggregator and spring based backends

aggregator.js

const express = require('express')
const app = express()
const request = require('request-promise');
const wrapRequest = require('zipkin-instrumentation-request');

const {
  Tracer,
  BatchRecorder,
  jsonEncoder: {JSON_V2}
} = require('zipkin');

const zipkinExpressMiddleware = require('zipkin-instrumentation-express').expressMiddleware
const CLSContext = require('zipkin-context-cls');
const {HttpLogger} = require('zipkin-transport-http');

const ctxImpl = new CLSContext();
const recorder = new BatchRecorder({
                     logger: new HttpLogger({
                       endpoint: 'http://localhost:9411/api/v2/spans',
                       jsonEncoder: JSON_V2
                     })
                   });
const serviceName = 'gateway-app';
const tracer = new Tracer({ctxImpl, recorder});

const zipkinRequest = wrapRequest(request, { tracer: tracer });

// Add the Zipkin middleware
app.use(zipkinExpressMiddleware({tracer,serviceName}))

app.get('/',  async (req, res) => {
  try {
      const traceMe1 = await zipkinRequest('http://localhost:8080/traceMe1')
      const traceMe2 = await zipkinRequest('http://localhost:8080/traceMe2')
      res.send(traceMe1+ " " +traceMe2)
    } catch (e) {
      console.log(e)
      res.sendStatus(500)
    }
});

app.listen(3000, () => console.log('Example app listening on port 3000!'))

application.properties

spring.zipkin.service.name=tracing-sample
spring.zipkin.sender.type=web
spring.zipkin.baseUrl=http://localhost:9411
spring.sleuth.sampler.percentage=1.0
spring.sleuth.sampler.probability=1.0

package.json

{
  "name": "gateway",
  "version": "1.0.0",
  "description": "",
  "main": "aggregator.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "noor",
  "license": "ISC",
  "dependencies": {
    "express": "^4.16.3",
    "express-http-proxy": "^1.2.0",
    "request": "^2.87.0",
    "request-promise": "^4.2.2",
    "zipkin": "^0.12.0",
    "zipkin-context-cls": "^0.11.0",
    "zipkin-instrumentation-express": "^0.12.0",
    "zipkin-instrumentation-request": "^0.12.0",
    "zipkin-transport-http": "^0.12.0"
  }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.tracing.sample</groupId>
	<artifactId>tracing-sample</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>tracing-sample</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.2.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
		<spring-cloud.version>Finchley.RC2</spring-cloud.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-webflux</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-zipkin</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-stream</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>io.projectreactor</groupId>
			<artifactId>reactor-test</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-stream-test-support</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.cloud</groupId>
				<artifactId>spring-cloud-dependencies</artifactId>
				<version>${spring-cloud.version}</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

	<repositories>
		<repository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
			<snapshots>
				<enabled>false</enabled>
			</snapshots>
		</repository>
	</repositories>
</project>

TracingSampleApplication.java

package com.tracing.sample.tracingsample;

import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
public class TracingSampleApplication {

	public static void main(String[] args) {
		SpringApplication.run(TracingSampleApplication.class, args);
	}
}

@RestController
class TracingController {

    private static final org.slf4j.Logger LOG = LoggerFactory.getLogger(TracingController.class);

    @GetMapping("/traceMe1")
    public String traceMe1(){
        LOG.info("hello");
        return "hello";
    }

    @GetMapping("/traceMe2")
    public String traceMe2(){
        LOG.info("world");
        return "world";
    }
}