Elastic's APM enabled web service sample code

server.js

// Elastic's APM enabled web service sample code

var apm = require('elastic-apm-node').start({
serviceName: 'Sample web service',
secretToken: '',
serverUrl: ''
})

var http = require('http');
var server = http.createServer();

var elasticsearch = require('elasticsearch');

function pi(){
  var span = apm.startSpan('Calculating Pi');
  var s = 0.0;
  for (var i = 0; i<=1e8; i++){
    s += Math.pow(-1.0, i) / (2*i + 1);
  }
  span.end();
  return String(4*s);
}

server.on("request", function(req, res) {

    if (req.url === "/") {
    apm.setTransactionName(req.method + " " + req.url);
    res.writeHead(200);
    res.write("Directories:\n");
    res.write("  /      : Show this info\n");
    res.write("  /pi    : Calculate pi\n");
    res.write("  /es    : Connect to Elasticsearch\n");
    res.write("  /err : Throw an exception\n");
    }
    else if (req.url === "/pi") {
    apm.setTransactionName(req.method + " " + req.url);
    res.writeHead(200);
    res.write(pi());
    }
    else if (req.url === "/es") {
    apm.setTransactionName(req.method + " " + req.url);
    var esclient = new elasticsearch.Client({ host: 'localhost:9201', log: 'trace', httpAuth: 'elastic:changeme' });
    esclient.ping().then(function(body){
        res.writeHead(200);
        res.write(JSON.stringify(body));
        }, function(error) {
        res.writehead(503);
        res.write(JSON.stringify(error));
        });
    }	else if (req.url === "/err") {
      apm.setTransactionName(req.method + " " + req.url);
      throw new Error("i'm a bug🐛");
    }
    else {
      res.writeHead(404);
      res.write("Not found");
    }

    res.end();
});

server.listen("8080", "localhost");