requestretry

What is requestretry?

The requestretry npm package is a wrapper around the popular request library that adds automatic retry functionality for failed HTTP requests. It allows you to specify retry strategies, including the number of retries, delay between retries, and conditions under which to retry.

What are requestretry's main functionalities?

Basic HTTP Request with Retry

This feature allows you to make an HTTP GET request with automatic retries. You can specify the maximum number of attempts, the delay between retries, and the retry strategy.

const request = require('requestretry');

request({
  url: 'https://api.example.com/data',
  method: 'GET',
  maxAttempts: 5,   // (default) try 5 times
  retryDelay: 5000, // (default) wait for 5s before trying again
  retryStrategy: request.RetryStrategies.HTTPOrNetworkError // (default) retry on 5xx or network errors
}, function (err, response, body) {
  if (err) {
    console.error('Failed:', err);
  } else {
    console.log('Success:', body);
  }
});

Custom Retry Strategy

This feature allows you to define a custom retry strategy. In this example, the request will be retried if there is an error or if the response status code is 502 (Bad Gateway).

const request = require('requestretry');

function myRetryStrategy(err, response, body) {
  // retry the request if we had an error or if the response was a 'Bad Gateway'
  return err || response.statusCode === 502;
}

request({
  url: 'https://api.example.com/data',
  method: 'GET',
  maxAttempts: 3,
  retryDelay: 3000,
  retryStrategy: myRetryStrategy
}, function (err, response, body) {
  if (err) {
    console.error('Failed:', err);
  } else {
    console.log('Success:', body);
  }
});

POST Request with Retry

This feature demonstrates how to make an HTTP POST request with automatic retries. The request includes a JSON body and will retry up to 4 times with a 2-second delay between attempts.

const request = require('requestretry');

request({
  url: 'https://api.example.com/data',
  method: 'POST',
  json: true,
  body: { key: 'value' },
  maxAttempts: 4,
  retryDelay: 2000,
  retryStrategy: request.RetryStrategies.HTTPOrNetworkError
}, function (err, response, body) {
  if (err) {
    console.error('Failed:', err);
  } else {
    console.log('Success:', body);
  }
});

Other packages similar to requestretry

axios-retry

axios-retry is a plugin for the axios HTTP client that adds retry functionality. It allows you to specify the number of retries, delay between retries, and conditions for retrying. Compared to requestretry, axios-retry is built on top of axios, which is a more modern and widely-used HTTP client than request.

got-retry

got-retry is a plugin for the got HTTP client that adds retry functionality. It provides a flexible retry mechanism with customizable options for retry count, delay, and conditions. got-retry is built on top of got, which is known for its simplicity and performance, making it a good alternative to requestretry.

superagent-retry

superagent-retry is a plugin for the superagent HTTP client that adds retry functionality. It allows you to specify the number of retries and conditions for retrying requests. superagent-retry is useful if you are already using superagent and need retry capabilities similar to those provided by requestretry.

README

request-retry - HTTP(s) request retry on recoverable errors.

---

When the connection fails with one of ECONNRESET, ENOTFOUND, ESOCKETTIMEDOUT, ETIMEDOUT, ECONNREFUSED, EHOSTUNREACH, EPIPE, EAI_AGAIN or when an HTTP 5xx or 429 error occurrs, the request will automatically be re-attempted as these are often recoverable errors and will go away on retry.

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Installation

Install with npm.

npm install --save requestretry

Usage

Request-retry is a drop-in replacement for request but adds two new options maxAttempts and retryDelay. It also adds one property to the response (or the error object, upon a network error), attempts. It supports callbacks or promises.

With callbacks

var request = require('requestretry');

request({
  url: 'https://api.domain.com/v1/a/b',
  json: true,

  // The below parameters are specific to request-retry
  maxAttempts: 5,   // (default) try 5 times
  retryDelay: 5000,  // (default) wait for 5s before trying again
  retryStrategy: request.RetryStrategies.HTTPOrNetworkError // (default) retry on 5xx or network errors
}, function(err, response, body){
  // this callback will only be called when the request succeeded or after maxAttempts or on error
  if (response) {
    console.log('The number of request attempts: ' + response.attempts);
  }
});

With promises

When you're using promises, you can pass the two following options:

• fullResponse (default true) - To resolve the promise with the full response or just the body
• promiseFactory (default whenjs) - A function to allow the usage of a different promise implementation library

request({
  url: 'https://api.domain.com/v1/a/b',
  json: true,

  fullResponse: true // (default) To resolve the promise with the full response or just the body
})
.then(function (response) {
  // response = The full response object or just the body
})
.catch(function(error) {
  // error = Any occurred error
})

Using promiseFactory option to use a different promise implementation library

// See the tests for different libraries usage examples

/**
 * @param  {Function} resolver The promise resolver function
 * @return {Object} The promise instance
 */
function customPromiseFactory(resolver) {
  // With when.js
  return require('when').promise(resolver);

  // With RSVP.js
  var Promise = require('rsvp').Promise;

  return new Promise(resolver);
}

request({
  url: 'https://api.domain.com/v1/a/b',
  json: true,

  // Custom promise factory function
  promiseFactory: customPromiseFactory
})
.then(function (response) {
  // response = The full response object or just the body
})
.catch(function(error) {
  // error = Any occurred error
})

How to define your own retry strategy

A retry strategy let you specify when request-retry should retry a request

/**
 * @param  {Null | Object} err
 * @param  {Object} response
 * @param  {Object} body
 * @param  {Object} options copy 
 * @return {Boolean} true if the request should be retried
 */
function myRetryStrategy(err, response, body, options){
  // retry the request if we had an error or if the response was a 'Bad Gateway'
  return !!err || response.statusCode === 502;
}

/**
 * @param  {Null | Object} err
 * @param  {Object} response
 * @param  {Object} body
 * @param  {Object} options copy 
 * @return {Object} mustRetry: {Boolean} true if the request should be retried
 *                  options: {Object} new options for request
 */
function myRetryStrategy(err, response, body, options){
  options.url = 'new url'; //you can overwrite some attributes or create new object 
  return {
    mustRetry: !!err || response.statusCode === 502,
    options: options, //then it should be passed back, it will be used for new requests
  }
}

/**
 * With an asynchronous retry strategy
 * @param  {Null | Object} err
 * @param  {Object} response
 * @param  {Object} body
 * @param  {Object} options copy 
 * @return {Object} mustRetry: {Boolean} true if the request should be retried
 *                  options: {Object} new options for request
 */
async function myRetryStrategy(err, response, body, options){
  let token = await getNewApiAuthToken();
  options.headers = {'Authorization': `Bearer ${token}`}
  return {
    mustRetry: true,
    options: options, // retry with new auth token
  }
}

request({
  url: 'https://api.domain.com/v1/a/b'
  json:true,
  retryStrategy: myRetryStrategy
}, function(err, response, body){
  // this callback will only be called when the request succeeded or after maxAttempts or on error
});

How to define your own delay strategy

A delay strategy let you specify how long request-retry should wait before trying again the request

/**
 * @param  {Null | Object} err
 * @param  {Object} response
 * @param  {Object} body
 * @return {Number} number of milliseconds to wait before trying again the request
 */
function myDelayStrategy(err, response, body){
  // set delay of retry to a random number between 500 and 3500 ms
  return Math.floor(Math.random() * (3500 - 500 + 1) + 500);
}

request({
  url: 'https://api.domain.com/v1/a/b'
  json:true,
  delayStrategy: myDelayStrategy // delayStrategy is called 1 less times than the maxAttempts set
}, function(err, response, body){
  // this callback will only be called when the request succeeded or after maxAttempts or on error
});

Here is how to implement an exponential backoff strategy:

/**
 * @param   {Number} attempts The number of times that the request has been attempted.
 * @return  {Number} number of milliseconds to wait before retrying again the request.
 */
function getExponentialBackoff(attempts) {
  return (Math.pow(2, attempts) * 100) + Math.floor(Math.random() * 50);
}

function constructExponentialBackoffStrategy() {
  let attempts = 0;
  return () => {
    attempts += 1;
    return getExponentialBackoff(attempts);
  };
}

request({
  url: 'https://api.domain.com/v1/a/b'
  json:true,
  delayStrategy: constructExponentialBackoffStrategy() // need to invoke the function to return the closure.
}, function(err, response, body){
  // this callback will only be called when the request succeeded or after maxAttempts or on error
});

How to access the underlying request library

You can access to the underlying request library thanks to request.Request:

const request = require('requestretry');
console.log(request.Request); // original request library

Thus, if needed, it's possible to monkey-patch or extend the underlying Request library:

request.Request = class extends request.Request {
  constructor(url, options, f, retryConfig) {
    super(url, options, f, retryConfig);
    // this constructor will be called for every requestretry call,
    // and give you global logging
    console.log('Request', url, options, f, retryConfig);
  }
}

Modifying request options

You can use the defaults method to provide default options like so:

var request = require('requestretry').defaults({ json: true, retryStrategy: myRetryStrategy });

API surface

As with request, several helpers are provided for various HTTP methods and usage:

• request(options [, callback]).
• request(url [, callback]) - same as request(options [, callback]).
• request(url, options [, callback]) - same as request(options [, callback]).
• request.get(url [, callback]) - same as request(options [, callback]), defaults options.method to GET.
• request.get(url, options [, callback]) - same as request(options [, callback]), defaults options.method to GET.
• request.head(url) - same as request(options [, callback]), defaults options.method to HEAD.
• request.post(url) - same as request(options [, callback]), defaults options.method to POST.
• request.put(url) - same as request(options [, callback]), defaults options.method to PUT.
• request.patch(url) - same as request(options [, callback]), defaults options.method to PATCH.
• request.del(url) - same as request(options [, callback]), defaults options.method to DELETE.
• request.delete(url) - same as request(options [, callback]), defaults options.method to DELETE.

Changelog

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I maintain this project in my free time, if it helped you, well, I would be grateful to buy a beer thanks to your paypal or Bitcoins, donation!

Francois-Guillaume Ribreau ([e-mail])

Changelog

5.0.0 (2021-02-16)

• Create FUNDING.yml (8d9e398)
• Hanlde EBUSY error from DNS resolver (dd80892), closes #128
• Release v5.0.0. (7b53cff)
• Update README.md (8d7ca0d)
• docs(changelog): updated (aa9c2ea)