@openreply/emw-request-id

Request ID Express Middleware

Application Load Balancers AWS enrich incoming http requests with an additional X-Amzn-Trace-Id header - see the aws documentation for more information.

Services like AWS API Gateway may set a x-amzn-RequestId header with an unique id for every incoming request.

We can use request tracing to track http requests from clients to targets or other services. This package associates a passed requestId with the req object or otherwise created a new one. It also adds the service under the configured name to the trace header list and makes it also available via the req object.

Getting Started

Installing

you can install this package via npm

npm i @openreply/emw-request-id

Usage

Simply add this module to your middleware chain

app.use(requestId({ serviceName: 'testService' }));

See the API documentation for more information regarding your initialization options.

this will extend the request object by the following properties

• req.trace (string, required) - a list of all nodes that appended to the trace in order newest to oldest in '[key]=[value];...' format
• req.traceHeader (string, required) - the name of the header that will be used to receive and pass on the trace id
• req.requestId (string, required) - in case a requestId has been passed with the request will be that headers value. Otherwise will contain a uuid specific to that request.

See the following usage example

/* eslint-disable import/no-extraneous-dependencies */
const request = require('request');
const express = require('express');
/* eslint-enable import/no-extraneous-dependencies */
const requestId = require('@openreply/emw-request-id');

const app = express();

// initializes our request-id middleware. will also set the trace header on
// the response object by default
app.use(requestId({ serviceName: 'testService' }));

app.get('/', (req, res) => {
  // log the trace and request information to the console
  // eslint-disable-next-line no-console
  console.log(`incoming request with requestId ${req.requestId} and trace ${req.trace} for trace header ${req.traceHeader}`);

  // add the trace information to requests to upstream servers
  request.get({
    url: 'http://www.example.com',
    headers: {
      [req.traceHeader]: req.trace
    }
  }, (error, response, body) => {
    if (error) {
      return res.sendStatus(502);
    }
    return res.send(body);
  });
});

app.listen(3000, () => {
  // eslint-disable-next-line no-console
  console.log('Example app listening on port 3000!');
});

Running the tests

You can run the test suite via

npm test

Versioning

We use SemVer for versioning. For the versions available, see the tags on this repository.

Authors

• Florian Schaper - Initial work - openreply-de

See also the list of authors who participated in this project.

License

This project is licensed under the MIT License - see the LICENSE.md file for details