ts-retry

This repository exports generic retry utilities. It leverages the promise-retry library under the hood. It extends it with an event emitter API and renames some of its configuration variables.

Retry configuration

The retry configuration uses the following values:

• minIntervalMs. The minimum wait time between attempts. Defaults to 1000.
• maxIntervalMs. The maximum wait time between attempts. Defaults to Infinity.
• factor. The exponential factor to use. See LINK. Defaults to 1.
• retries. The amount of retries made (not including the first call). Defaults to 60.
• isRetryableError. A predicate function that determines whether an error should trigger a retry. Defaults to () => true.

You invoke it as such with the default configuration:

import {retry} from "@infra-blocks/retry";

// This promise resolves when `myFunc` resolves, or rejects with the last error returned
// by `myFunc` on that last retry.
await retry(myFunc);

To tweak its behaviors, simply pass the desired modifications as the second argument to the retry invocation:

await retry(
    myFunc,
    {
        retries: 9,
        factor: 2,
        minIntervalMs: 150,
        maxIntervalMs: 20_000,
        isRetryableError: (err) => err.name === "RetryableError"
    }
);

Event emitter API

The API also allows caller code to subscribe to attempt and retry events. attempt events are emitted on every attempt, including the first. retry events only start being emitted on the second attempt, meaning an error always occurred before a retry event.

The attempt event handler has the following call signature:

(params: {
    attempt: number; // Starts at 1.
    retryConfig: Required<RetryConfig<E>>; // This is the effective retry configuration used. 
}) => void;`

And the retry event handler has the following call signature:

(params: {
    retry: number; // Starts at 1.
    retryConfig: Required<RetryConfig<E>>;
}) => void;

Example:

await retry(startMongoDbContainer)
    .once("attempt", () => logger.info("starting MongoDB container"))
    .on("retry", ({retry}) => logger.debug(`polling MongoDB for health check, retry: ${retry}`));