env-guard

ENV Guard

env-guard is built in TypeScript and provides simple methods for validating and exporting environment variables.

env-guard supports the idea that all environment config should be validated at application boot (or build time for React etc) and should exit immediately if validation fails. And that config should then only be exported and accessed from one location.

Install

npm install --save env-guard

Type definitions are bundled and do not require a separate install.

Usage

// config.js

import { getStringEnv, getNumberEnv, getBooleanEnv } from 'env-guard';

// Get a string value.
export const STRING_EXAMPLE_1 = getStringEnv('STRING_EXAMPLE_1');
// Get a string value with a set of possibilities.
export const STRING_EXAMPLE_2 = getStringEnv('STRING_EXAMPLE_2', ['these', 'are', 'valid']);

// Get a number value.
export const NUMBER_EXAMPLE_1 = getNumberEnv('NUMBER_EXAMPLE_1');
// Get a number value with a set of possibilities.
export const NUMBER_EXAMPLE_2 = getNumberEnv('NUMBER_EXAMPLE_2', [1, 2, 3]);

// Get a boolean value
export const BOOLEAN_EXAMPLE = getBooleanEnv('BOOLEAN_EXAMPLE');

// If any value does not pass validation, one of the following errors will be thrown.

// EnvMissing
// EnvInvalidType
// EnvInvalidPossibility

console.log([STRING_EXAMPLE_1, STRING_EXAMPLE_2, NUMBER_EXAMPLE_1, NUMBER_EXAMPLE_2, BOOLEAN_EXAMPLE]);

If we attempt to run the application, it will exit at the first validation failure.

$ node ./config.js
Error: Envionment variable [STRING_EXAMPLE_1] is not set.

Passing all the required variables will allow the application to run.

$ STRING_EXAMPLE_1=a STRING_EXAMPLE_2=valid NUMBER_EXAMPLE_1=1 NUMBER_EXAMPLE_2=3 BOOLEAN_EXAMPLE=true node ./config.js
[ 'a', 'valid', 1, 3, true ]