Special custom middleware for expressjs 🚀

This project consists of being a collection of middlewares created for expressjs. In order to have a focus on monitoring and traceability designed for production ready api-rest.

Index:

Middleware list
How to use?
Including order
Middleware specification
Usage diagram
Usage examples

List of middleware

Take a look in the folder /src/server/middleware.

Name	Description
expressLogger.js	Log all request and response received, inject traceability ids.
restrict.js	Allow a request only if have an authorization header.
tokenDecoder.js	Inject in the context clienId from jwt and in the request object.
traceability.js	Inject in the request and the context the traceability from headers.
logger.js	A JSON logger module to log stdout always in this format, inject the traces and client value.

How to use?

Create a js file and import the middleware and bind in express app.

const httpContext = require('express-http-context');

//Load custom middlewares
const {
  traceabilityContext,
  token2Context,
  expressLogger
} = require('./middleware');

//Start Express-js.
const app = express();
const server = http.createServer(app);

//Parse the request to use the body for the events.
app.use(httpContext.middleware);
app.use(traceabilityContext);
app.use(token2Context);
app.use(expressLogger);

Logger In the file /src/server/controller/home.js* the logger module, generate a stdout including some special values "client,traceId".

const logger = require('../lib/logger');

const home = async (req, res, next) => {  

  logger.log({
    message:'Processing home',
    value:'activated'
  });

  const mock = process();

  res.status(200).json({
    mock
  });

};

In the file /src/server/services/testService.js* the logger module, generate a stdout including some special values "client,traceId".

const logger = require('../lib/logger');

/**
 * Parse the client result.notification.parse(result[0]['body']),
 * @param {object} receive the db object.
 * @returns {object}
 */
const process = () => {

  logger.info('Run process test service');

  return {
    name:'Damian Cipolat',
    mone:'2000.00',
    benefits:[
      'golf',
      'psx',
      'netflix'
    ]
  };

}

ORDER:

Respect the use of the middlewares with the next order.

app.use(httpContext.middleware);   //1 --> Use NPM express-http-context module.
app.use(traceabilityContext);      //2 --> Request traceability.
app.use(token2Context);            //3 --> Context loader.
app.use(expressLogger);            //4 --> Request logger.

Detail:

1) traceability:

Extract the header x-correlation-id include this value in the request object with the attibute traceId and store in the context the traceId value,

2) tokenDecoder:

Extract the "sub" claim from the "authorization" header decoding the JWT token, modify the expressjs request object adding "clientId" attribute", append in the context the "client" value with the "sub" value from jwt.

3) expressLogger:

This middleware log the request and response value received in the api.

Diagram, traceability:

The diagram explain the use of the traceability id's with this project.

Examples:

In this section you can test the middleware, I include information about the stdout in each request.

Example °1:

Try the next CURL with the running api.

REQUEST

curl --location --request GET 'http://127.0.0.1:8000/home' \
--header 'x-correlation-id: 1213123213123213213123' \
--header 'Authorization: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c' \
--header 'Content-Type: application/json' \
--data-raw '{
    "name":"damian"
}'

STDOUT

> node ./src/server/index.js

Running 8000
{"level":"LOG","code":0,"time":1613712617329,"message":"Received request","url":"/home","method":"GET","traceId":"1213123213123213213123","client":"1234567890"}
{"level":"LOG","code":0,"time":1613712617330,"message":"Processing home","value":"activated","traceId":"1213123213123213213123","client":"1234567890"}
{"level":"INFO","code":0,"time":1613712617330,"message":"Run process test service","traceId":"1213123213123213213123","client":"1234567890"}
{"level":"LOG","code":0,"time":1613712617330,"message":"Response request","url":"/","status":200,"method":"GET","traceId":"1213123213123213213123","client":"1234567890","response":{"mock":{"name":"Damian Cipolat","mone":"2000.00","benefits":["golf","psx","netflix"]}}}

Traceability Take a look in the stdout, the expresslogger and the logger lib, extract the traceId and client from the headers and jwt.

Example °2: