getenv

Helper to get and typecast environment variables. This is especially useful if you are building Twelve-Factor-Apps where all configuration is stored in the environment.

Installation

npm install getenv

TypeScript types are available from the @types/getenv module.

Usage

Set environment variables:

export HTTP_HOST="localhost"
export HTTP_PORT=8080
export HTTP_START=true
export AB_TEST_RATIO=0.5
export KEYWORDS="sports,business"
export PRIMES="2,3,5,7"

Get and use them:

const getenv = require('getenv');

const host = getenv('HTTP_HOST'); // same as getenv.string('HTTP_HOST');
const port = getenv.int('HTTP_PORT');
const start = getenv.bool('HTTP_START');

if (start === true) {
  // const server = http.createServer();
  // server.listen(port, host);
}

const abTestRatio = getenv.float('AB_TEST_RATIO');

if (Math.random() < abTestRatio) {
  // test A
} else {
  // test B
}

const keywords = getenv.array('KEYWORDS');
keywords.forEach(function(keyword) {
  // console.log(keyword);
});

const primes = getenv.array('PRIMES', 'int');
primes.forEach(function(prime) {
  // console.log(prime, typeof prime);
});

Methods

All methods accept a fallback value that will be returned if the requested environment variable is not set. If the fallback value is omitted and if the requested environment variable does not exist, an exception is thrown.

env(name, [fallback])

Alias for env.string(name, [fallback]).

env.string(name, [fallback])

Return as string.

env.int(name, [fallback])

Return as integer number.

env.float(name, [fallback])

Return as float number.

env.bool(name, [fallback])

Return as boolean. Only allows true/false as valid values.

env.boolish(name, [fallback])

Return as boolean. Allows true/false/1/0 as valid values.

env.array(name, [type], [fallback])

Split value of the environment variable at each comma and return the resulting array where each value has been typecast according to the type parameter. An array can be provided as fallback.

env.multi({spec})

Return a list of environment variables based on a spec:

const config = getenv.multi({
  foo: 'FOO', // throws if FOO doesn't exist
  bar: ['BAR', 'defaultval'], // set a default value
  baz: ['BAZ', 'defaultval', 'string'], // parse into type
  quux: ['QUUX', undefined, 'int'], // parse & throw
});

env.url(name, [fallback])

Return a parsed URL as per Node's require("url").parse. N.B url doesn't validate URLs, so be sure it includes a protocol or you'll get deeply weird results.

const serviceUrl = getenv.url('SERVICE_URL');

serviceUrl.port; // parsed port number

env.disableFallbacks()

Disallows fallbacks in environments where you don't want to rely on brittle development defaults (e.g production, integration testing). For example, to disable fallbacks if we indicate production via NODE_ENV:

if (process.env.NODE_ENV === 'production') {
  getenv.disableFallbacks();
}

env.disableErrors()

getenv won't throw any error. If a fallback value is provided, that will be returned, else undefined is returned.

getenv.disableErrors();
console.log(getenv('RANDOM'));
// undefined

env.enableErrors()

Revert the effect of disableErrors().

getenv.disableErrors();
console.log(getenv('RANDOM'));
// undefined

getenv.enableErrors();
console.log(getenv('RANDOM'));
// Error: GetEnv.Nonexistent: RANDOM does not exist and no fallback value provided.

Changelog

v1.0.0

Drop support for Node.js older than 6.
Modernize code.
Add MIT License in package.json and LICENSE.md.

v0.7.0

Add env.disableErrors() / getenv.enableErrors() support.

v0.6.0

Added getenv.boolish() support.

v0.5.0

Add getenv.url() support.

v0.4.0

Add getenv.disableFallbacks() support.

v0.3.0

Add getenv.multi() support.

v0.2.0

Rename git repository

v0.1.0

Initial release

Authors

Moritz von Hase (initial author)
Christoph Tavan dev@tavan.de
Jonas Dohse jonas@dohse.ch
Jan Lehnardt (@janl): getenv.multi() support.
Tim Ruffles timruffles@gmail.com: disableFallbacks(), url()
Ashwani Agarwal ashwani.a@outlook.com: disableErrors(), enableErrors()