retry.ts

// Copyright 2018 Google LLC
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import {GaxiosError} from './common';

export async function getRetryConfig(err: GaxiosError) {
  let config = getConfig(err);
  if (!err || !err.config || (!config && !err.config.retry)) {
    return {shouldRetry: false};
  }
  config = config || {};
  config.currentRetryAttempt = config.currentRetryAttempt || 0;
  config.retry =
    config.retry === undefined || config.retry === null ? 3 : config.retry;
  config.httpMethodsToRetry = config.httpMethodsToRetry || [
    'GET',
    'HEAD',
    'PUT',
    'OPTIONS',
    'DELETE',
  ];
  config.noResponseRetries =
    config.noResponseRetries === undefined || config.noResponseRetries === null
      ? 2
      : config.noResponseRetries;

  // If this wasn't in the list of status codes where we want
  // to automatically retry, return.
  const retryRanges = [
    // https://en.wikipedia.org/wiki/List_of_HTTP_status_codes
    // 1xx - Retry (Informational, request still processing)
    // 2xx - Do not retry (Success)
    // 3xx - Do not retry (Redirect)
    // 4xx - Do not retry (Client errors)
    // 429 - Retry ("Too Many Requests")
    // 5xx - Retry (Server errors)
    [100, 199],
    [429, 429],
    [500, 599],
  ];
  config.statusCodesToRetry = config.statusCodesToRetry || retryRanges;

  // Put the config back into the err
  err.config.retryConfig = config;

  // Determine if we should retry the request
  const shouldRetryFn = config.shouldRetry || shouldRetryRequest;
  if (!(await shouldRetryFn(err))) {
    return {shouldRetry: false, config: err.config};
  }

  // Calculate time to wait with exponential backoff.
  // Formula: (2^c - 1 / 2) * 1000
  const delay = ((Math.pow(2, config.currentRetryAttempt) - 1) / 2) * 1000;

  // We're going to retry!  Incremenent the counter.
  err.config.retryConfig!.currentRetryAttempt! += 1;

  // Create a promise that invokes the retry after the backOffDelay
  const backoff = new Promise(resolve => {
    setTimeout(resolve, delay);
  });

  // Notify the user if they added an `onRetryAttempt` handler
  if (config.onRetryAttempt) {
    config.onRetryAttempt(err);
  }

  // Return the promise in which recalls Gaxios to retry the request
  await backoff;
  return {shouldRetry: true, config: err.config};
}

/**
 * Determine based on config if we should retry the request.
 * @param err The GaxiosError passed to the interceptor.
 */
function shouldRetryRequest(err: GaxiosError) {
  const config = getConfig(err);

  // node-fetch raises an AbortError if signaled:
  // https://github.com/bitinn/node-fetch#request-cancellation-with-abortsignal
  if (err.name === 'AbortError') {
    return false;
  }

  // If there's no config, or retries are disabled, return.
  if (!config || config.retry === 0) {
    return false;
  }

  // Check if this error has no response (ETIMEDOUT, ENOTFOUND, etc)
  if (
    !err.response &&
    (config.currentRetryAttempt || 0) >= config.noResponseRetries!
  ) {
    return false;
  }

  // Only retry with configured HttpMethods.
  if (
    !err.config.method ||
    config.httpMethodsToRetry!.indexOf(err.config.method.toUpperCase()) < 0
  ) {
    return false;
  }

  // If this wasn't in the list of status codes where we want
  // to automatically retry, return.
  if (err.response && err.response.status) {
    let isInRange = false;
    for (const [min, max] of config.statusCodesToRetry!) {
      const status = err.response.status;
      if (status >= min && status <= max) {
        isInRange = true;
        break;
      }
    }
    if (!isInRange) {
      return false;
    }
  }

  // If we are out of retry attempts, return
  config.currentRetryAttempt = config.currentRetryAttempt || 0;
  if (config.currentRetryAttempt >= config.retry!) {
    return false;
  }

  return true;
}

/**
 * Acquire the raxConfig object from an GaxiosError if available.
 * @param err The Gaxios error with a config object.
 */
function getConfig(err: GaxiosError) {
  if (err && err.config && err.config.retryConfig) {
    return err.config.retryConfig;
  }
  return;
}