@vercel/fetch-retry

A layer on top of fetch (via node-fetch) with sensible defaults for retrying to prevent common errors.

How to use

fetch-retry is a drop-in replacement for fetch:

const fetch = require('@vercel/fetch-retry')(require('node-fetch'))

module.exports = async () => {
  const res = await fetch('http://localhost:3000')
  console.log(res.status);
}

Make sure to yarn add @vercel/fetch-retry in your main package.

Note that you can pass retry options to using opts.retry. We also provide a opts.onRetry and opts.retry.maxRetryAfter options.

opts.onRetry is a customized version of opts.retry.onRetry and passes not only the error object in each retry but also the current opts object.

opts.retry.maxRetryAfter is the max wait time according to the Retry-After header. If it exceeds the option value, stop retrying and returns the error response. It defaults to 20.

Rationale

Some errors are very common in production (like the underlying Socket yielding ECONNRESET), and can easily and instantly be remediated by retrying.

The default behavior of fetch-retry is to attempt retries 10, 60 360, 2160 and 12960 milliseconds (a total of 5 retries) after a network error, 429 or 5xx error occur.

The idea is to provide a sensible default: most applications should continue to perform correctly with a worst case scenario of a given request having an additional 15550ms overhead.

On the other hand, most applications that use fetch-retry instead of vanilla fetch should see lower rates of common errors and fewer 'glitches' in production.

Tests

To run rests, execute

npm test