node server with correlationId pass though

server_with_correlationId.js

const express = require('express');
const bodyParser = require('body-parser');
const pino = require('express-pino-logger');
const uuid = require('uuid');
const axios = require('axios');
const app = express();
const port = 3000;

function correlationIdMiddleware (options) {
  const headerName = (options && options.header) || 'x-correlation-id';
  return (req, res, next) => {
    const id = req.get(headerName);
    req.correlationId = id || uuid.v4();
    next();
  };
}

app.use(correlationIdMiddleware());
app.use(pino({
  genReqId: (req) => {
    return req.correlationId;
  }
}));

app.use(bodyParser.json());

const someService = async (log, httpClient, data) => {
  const transformed = {
    ...data,
    somethingElse: 'hi'
  };
  log.info('getting some data');
  const result = await httpClient.post('https://postman-echo.com/post', transformed);
  log.info('got some data');
  return result.data;
};

const createHttpClient = (log, request) => {
  const { correlationId } = request;
  const instance = axios.create({
    headers: {'x-correlation-id': correlationId}
  });
  instance.interceptors.request.use(request => {
    log.info(request);
    return request
  });
  instance.interceptors.response.use(response => {
    // might need to change this as 
    // response has a lot of crap on it
    log.info(response);
    return response
  });
  return instance;
};

app.get('/', async (req, res) => {
  const { log } = req;
  const httpClient = createHttpClient(log, req);
  let transformedData;
  try {
    transformedData = await someService(log, httpClient, req.body);
  } catch (e) {
    log.error(e);
    return res.status(500).json({
      message: 'Sorry an error has occurred'
    });
  }
  return res.json(transformedData);
});

app.listen(port, () => console.log(`Example app listening on port ${port}!`));