• Installation
• Usage
• Stats
• Testing and linting

HTTP transport EMF stats

EMF stats is a plugin that can be used by http-transport to return a stats object alongside the HTTP response.

Installation

npm install @bbc/http-transport-emf-stats

or

yarn add @bbc/http-transport-emf-stats

Usage

import HttpTransport from '@bbc/http-transport';

const client = HttpTransport
  .createBuilder()
  .userAgent('...')
  .retries(...)
  .retryDelay(...)
  .use(stats())
  .createClient();

With the cache enabled

Used in conjunction with @bbc/http-transport-cache

import HttpTransport from '@bbc/http-transport';
import { maxAge, staleIfError } from '@bbc/http-transport-cache';

const catbox = ...; // a catbox instance

const cacheOpts = {
  name: 'rms',
  ...
  ...
}

const client = HttpTransport
  .createBuilder()
  .userAgent('...')
  .retries(...)
  .retryDelay(...)
  .use(stats())
  .use(maxAge(catbox, cacheOpts))
  .use(staleIfError(catbox, cacheOpts))
  .createClient();

Stats

The stats object is structured as following:

{
  metrics: {
    attemptCount: 0, // The number of request attempts in total. This number is equal to "attempts.length".
    retryCount: 0, // The number of retried attempts. This number is equal to "attemptCount - 1".
    requestCount: 0, // The number of times a request is sent to and a response is received from the upstream
    requestErrorCount: 0, // The number of times the upstream service doesn't respond
    response5xxCount: 0, // The number of 5xx responses
    response4xxCount: 0, // The number of 4xx responses
    response3xxCount: 0, // The number of 3XX responses
    response2xxCount: 0, // The number of 2XX responses
    response1xxCount: 0, // The number of 1XX responses
    responseInvalidCount: 0, // The number of invalid response statuses
    responseTime: 0,
    cacheHitCount: 0,
    cacheMissCount: 0,
    cacheStaleCount: 0,
    cacheErrorCount: 0,
    cacheTimeoutCount: 0,
    cacheConnectionErrorCount: 0
  },
  cacheAudit: [] // A list of cache events triggered by the cache plugin. It is used for troubleshooting purposes only.
}

The stats object is set within res when the request resolves or in the error object when it rejects. If you want to access the stats info do as following:

try {
  const response = await client.get(uri).asResponse();
  const { stats } = response.res;

  // can access stats data
} catch (error) {
  const { stats } = error;

  // can access stats data
}

Testing and linting

To run unit tests and coverage reports

npm run test

or just tests without coverage report

npm run test:only

To run code linting

npm run lint