aws-xray-sdk-express

What is aws-xray-sdk-express?

The aws-xray-sdk-express npm package is a middleware for Express.js applications that integrates with AWS X-Ray to trace and analyze requests. It helps in monitoring and debugging applications by providing detailed insights into the performance and behavior of your application.

What are aws-xray-sdk-express's main functionalities?

Automatic Request Tracing

This feature allows you to automatically trace incoming HTTP requests. The middleware captures the request and response cycle, creating segments that can be visualized in the AWS X-Ray console.

const express = require('express');
const AWSXRay = require('aws-xray-sdk');
const app = express();

app.use(AWSXRay.express.openSegment('MyApp'));

app.get('/', (req, res) => {
  res.send('Hello World!');
});

app.use(AWSXRay.express.closeSegment());

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

Custom Subsegments

This feature allows you to create custom subsegments within a segment. This is useful for tracing specific parts of your code, such as database queries or external API calls.

const express = require('express');
const AWSXRay = require('aws-xray-sdk');
const app = express();

app.use(AWSXRay.express.openSegment('MyApp'));

app.get('/custom', (req, res) => {
  const segment = AWSXRay.getSegment();
  const subsegment = segment.addNewSubsegment('customSubsegment');
  // Perform some operations
  subsegment.close();
  res.send('Custom Subsegment');
});

app.use(AWSXRay.express.closeSegment());

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

Error Capturing

This feature allows you to capture and record errors that occur during the request lifecycle. The errors are sent to AWS X-Ray, where they can be analyzed to identify and fix issues.

const express = require('express');
const AWSXRay = require('aws-xray-sdk');
const app = express();

app.use(AWSXRay.express.openSegment('MyApp'));

app.get('/error', (req, res) => {
  const segment = AWSXRay.getSegment();
  try {
    throw new Error('Something went wrong!');
  } catch (err) {
    segment.addError(err);
    res.status(500).send('Internal Server Error');
  }
});

app.use(AWSXRay.express.closeSegment());

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

Other packages similar to aws-xray-sdk-express

newrelic

New Relic is a comprehensive monitoring and observability platform that provides detailed insights into application performance. It offers similar request tracing and error capturing functionalities but also includes advanced features like infrastructure monitoring, synthetic monitoring, and more. Unlike aws-xray-sdk-express, New Relic is a third-party service and requires a subscription.

datadog

Datadog is another monitoring and analytics platform that provides end-to-end visibility into application performance. It offers request tracing, error tracking, and custom metrics similar to aws-xray-sdk-express. Datadog also includes features for infrastructure monitoring, log management, and security monitoring. It is a third-party service and requires a subscription.

opentelemetry

OpenTelemetry is an open-source observability framework that provides APIs and tools for collecting metrics, logs, and traces. It offers similar functionalities to aws-xray-sdk-express, such as request tracing and custom subsegments. OpenTelemetry is highly extensible and can be integrated with various backends, including AWS X-Ray, making it a versatile choice for observability.

README

Requirements

• AWS X-Ray SDK Core (aws-xray-sdk-core)
• Express 4.14.0 or greater

AWS X-Ray and Express

The AWS X-Ray Express package automatically records information for incoming and outgoing requests and responses, via the middleware functions in this package. To configure sampling, dynamic naming, and more see the set up section.

The AWS X-Ray SDK Core has two modes - manual and automatic. Automatic mode uses the cls-hooked package and automatically tracks the current segment and subsegment. This is the default mode. Manual mode requires that you pass around the segment reference.

In automatic mode, you can get the current segment/subsegment at any time:

var segment = AWSXRay.getSegment();

In manual mode, you can get the base segment off of the request object:

var segment = req.segment;

Middleware Usage

The X-Ray SDK provides two middlewares: AWSXRay.express.openSegment(<name>) and AWSXRay.express.closeSegment(). These two middlewares must be used together and wrap all of your defined routes that you'd like to trace. In automatic mode, the openSegment middleware must be the last middleware added before defining routes, and the closeSegment middleware must be the first middleware added after defining routes. Otherwise issues with the cls-hooked context may occur.

Sample App

To get started with a functional express application instrumented with the X-Ray SDK, check out our sample app.

Automatic mode example

For more automatic mode examples, see the Automatic Mode Examples.

Capture all incoming requests to / and /directory

var AWSXRay = require('aws-xray-sdk-core');
var xrayExpress = require('aws-xray-sdk-express');
var app = express();

//...

app.use(xrayExpress.openSegment('defaultName'));

app.get('/', function (req, res) {
  var segment = AWSXRay.getSegment();
  segment.addAnnotation('page', 'home');

  //...

  res.render('index');
});

app.get('/directory', function (req, res) {
  var segment = AWSXRay.getSegment();
  segment.addAnnotation('page', 'directory');

  //...

  res.render('directory');
});

app.use(xrayExpress.closeSegment());

Manual mode examples

For more manual mode examples, e.g. what to do with the segment inside your route logic, see the Manual Mode Examples. Note that you don't have to manually start or close the segments since that is handled by the X-Ray middleware.

Capture All incoming requests to /

var AWSXRay = require('aws-xray-sdk-core');
var xrayExpress = require('aws-xray-sdk-express');
var app = express();

//...

var AWSXRay = require('aws-xray-sdk');

//Required at the start of your routes
app.use(xrayExpress.openSegment('defaultName'));

app.get('/', function (req, res) {
  var segment = req.segment;

  //...

  res.render('index');
});

app.use(xrayExpress.closeSegment());   //Required at the end of your routes / first in error handling routes