env-agent

A zero-dependency package for reading environment variables into process.env at runtime. Easily parse, load and expand environment variables from .env files. Provides sanity checks when parsing .env files and ensures all incoming variables are defined before being added to process.env.

Installation

npm:

$ npm install env-agent --save

yarn:

$ yarn add env-agent

Usage

Ensure you have a .env file in the root of your project. This file should contain all the environment variables you want to use in your project. For example:

# .env
PORT=3000
NODE_ENV=development

Then, in your project, import the env-agent package and call the load function:

It is highly recommended to call the load function as early as possible in your project. This will ensure all environment variables are available to your project as soon as possible.

CommonJS:

const envAgent = require('env-agent').default;

envAgent.load();

ES6:

import envAgent from 'env-agent';

envAgent.load();

// {
//   PORT: 3000,
//   NODE_ENV: 'development'
// }

Now all the environment variables defined in your .env file are available in process.env.

API

load([, options])

loads the environment variables defined in your .env file. This function should be called as early as possible in your project.

options

Option	Type	Default	Description
silent	boolean	true	When attempting to load the .env file, specify whether errors should be thrown or not.
strict	boolean	false	Ensures variables are defined before being added to process.env.
path	string	process.cwd()	The path to the .env file.
expand	string	'none'	Choose to expand variables defined in your .env file.
overwrite	boolean	false	Overwrite existing environment variables.
encoding	string	'utf8'	The encoding of the .env file when reading.
debug	boolean	false	Show debug messages when loading the .env file.
template	string	undefined	Define a template to validate the .env file against.

envAgent.load({
    silent: false,
    debug: true
});

parse(file)

Parses the input and returns an object containing the environment variables.

const env = envAgent.parse(`
    PORT=3000
    NODE_ENV=development
`);

// or

const env = envAgent.parse(Buffer.from('PORT=3000\nNODE_ENV=development'));

expand(variables, expansionMode)

Choose to expand variables defined in your .env file. It is recommened to expand variables when calling envAgent.load(). Select the expansion mode that best suits your needs.

• none - No expansion will be performed.
• project - Expand variables defined in the .env file (does not expand current process.env variables).
• machine - Expand variables defined on your machine's environment (expands current process.env variables).

envAgent.load({ expand: "project" }) // variables will automatically expand

// or

const variables = envAgent.load();

envAgent.expand(variables, "project"); // variables will expand

You can denote a variable to be expanded by using the following syntax:

• $VARIABLE
• ${VARIABLE}

# .env
PORT=3000
NODE_ENV=development
HOST=localhost
URL=http://${HOST}:$PORT # HOST and PORT will be expanded

envAgent.load({ expand: "project" });

// {
//   PORT: 3000,
//   NODE_ENV: 'development',
//   HOST: 'localhost',
//   URL: 'http://localhost:3000'
// }

get(key)

Retrieve a single environment variable from process.env.

set(key, value[, overwrite])

Sets a single environment variable in process.env. Ensures configuration rules are followed:

• If strict is true, the variable must be defined before being added to process.env.
• If overwrite is false, the variable must not already exist in process.env.
• If expand is true, the variable will be overwritten with the value.

delete(key)

Deletes a single environment variable from process.env.

CHANGELOG

See CHANGELOG.md

LICENSE

See LICENSE