Timebomb

Timebomb is a tiny cross-language library for failing loudly after a certain date or time has passed.

• JS installation via npm install --save timebomb-js
• Python installation via pip install timebomb

The Problem

Migrations leave TODOs all over the place. After a migration is completed, these todos linger on for weeks, months, and years. If only there was a way to make absolutely sure that you revisited them before a certain date...

The solution

Fail loudly and violently if the date passes.

This comes in 3 varieties, in increasing aggressiveness:

1. warnAfter
2. slowAfter
3. failAfter

warnAfter

Timebomb provides the ability to throw a warning after a certain date:

import timebomb from "timebomb-js";

function foo(bar) {
  // Temporary workaround: bar.hack() is required because of x/y/z reasons
  timebomb.warnAfter(new Date("2021-10-30"));
  bar.hack();
}

slowAfter

Timebomb provides the ability to add arbitrary latency after a certain date:

import timebomb from "timebomb-js";

function foo(bar) {
  // Temporary workaround: bar.hack() is required because of x/y/z reasons
  timebomb.slowAfter(new Date("2021-10-30"), 100);
  bar.hack();
}

This ensures that if some migration goes on too long, then the un-migrated code is far slower than a refactored implementation.

If you need to force other people to move away from a deprecated method progressively, perhaps if you've got a deprecated endpoint or sdk method, you can specify a progressive latency increase. This will ensure that important requests get migrated first, followed by less important ones:

import timebomb from "timebomb-js";

function deprecatedFoo(bar) {
  // Don't use this method after 2021-10-30, as it's being deprecated
  timebomb.slowAfter(new Date("2021-10-30"), (daysLate) => 100 * daysLate);
  bar.doSomethingWrong();
}

This will provide a warning for a week before failing, and slow the implementation afterwards.

failAfter

If nothing else works, the most extreme option is to outright fail the request.

import timebomb from "timebomb-js";

function foo(bar) {
  // Temporary workaround: bar.hack() is required because of x/y/z reasons
  timebomb.failAfter(Date("2021-10-30"));
  bar.hack();
}

This will provide a warning for a week before failing, and throw an error afterwards.

timebomb-js Specifics

This section deals with the specifics of timebomb-js in Javascript

Disabling warnings / errors / slowdown in production

You can automatically disable the effects of timebomb in production by importing from timebomb/nonprod instead.

import { warnAfter, slowAfter, failAfter } from "timebomb-js/nonprod";

// Will be disabled if this code runs in production
warnAfter([...])

Configuration

Each of the functions takes an additional optional argument, called options.

warnAfter(new Date("2021-10-30"), options);
slowAfter(new Date("2021-10-30"), 200, options);
failAfter(new Date("2021-10-30"), options);

Options is an object with the following keys:

Key	type	default	description
warningPeriodInDays	number	7	How many days before expiry to warn the user
warnFunction	(string) => any	builtin	What function gets called when timebomb warns?
failFunction	(string) => any	builtin	What function gets called when timebomb fails?
shouldDisableInProd	boolean	false	Whether to disable timebomb's effects in prod
prodDetectFunction	() => boolean	builtin	How timebomb detects whether env is prod.

Changing configuration globally

If you want to change the behavior of timebomb globally, you can use the updateConfig() function provided by timebomb to update the default config.

import { updateDefaultConfig } from "timebomb-js";

updateDefaultConfig({
  warnFunction: (str: string) => reportToBackend(str) && console.warn(str),
});