To prevent code duplication and enhance re-usability, a centralized configuration including all of your environment variables might be handy. Rather of generating a .env file for each package, we may utilize a single .env file at the project's root.

This is a package that allows monorepo applications and packages to share and load a centralized dotenv. It's based over dotenv package.

It also includes some extra features such as manipulation and saving of changes to the dotenv file, a default centralized file, and a file loader with ordering and priorities.

The plugin dotenv-expand is enabled by default.

├── .env
├── .env.production
├── .env.defaults
├── packages
│   ├── ui-library
│   ├── other-library
├── apps
│   ├── web
│   │   ├── .storybook
│   ├── docs

The package search the first .env file, matching with some priority criteria, by walking up the parent directories.

Starting from the current process directory, this package finds the first file that matches the best filepath and filename criteria with the highest priority. The greater the depth of the up folder, the lesser its priority.

The priority can be customized on the configuration with the priorities property, see the example below on the usage section.

Note: The allowed values for NODE_ENV are usually test, development and production.

Given the following folder structure with dotenv files:

├── .env
├── .env.production
├── apps
│   ├── .env.development
│   ├── web
│   ├── docs
│   │   ├── .env
│   │   ├── .env.local

Having the following priority order:

Then we will have the following outcome scenarios:

Install the library from npm or yarn just running one of the following command lines:

For custom advanced configuration of Next.js, you can create a next.config.js or next.config.mjs file in the root of your project directory (next to package.json).

Add the following line at the top of the file:

require("dotenv-mono").load();

require("dotenv-mono").load();

/**
 * @type {import('next').NextConfig}
 */
const nextConfig = {
	/* config options here */
};

module.exports = nextConfig;

The main configuration file is .storybook/main.js. This file controls the Storybook server's behavior, so you must restart Storybook’s process when you change it.

Add the following lines on the file:

const dotenv = require("dotenv-mono").load();

const config = {
	/* config options here */
	env: (config) => {
		return {
			...config,
			...dotenv.env,
		};
	},
};

module.exports = config;

Simple methods to export environment variables from the dotenv into the working process. Here are several potential implementation approaches based on your preferences.

// Inline
require("dotenv-mono").load(/* config */);

// Using the function
const {dotenvLoad} = require("dotenv-mono");
dotenvLoad(/* config */);

// Using import
import {dotenvLoad} from "dotenv-mono";
const dotenv = dotenvLoad(); // Dotenv instance

// Using the class
const {Dotenv} = require("dotenv-mono");
const dotenv = new Dotenv(/* config */);
dotenv.load();

If you need a fast way to replace dotenv package with dotenv-mono, and you need also to have a retro-compatible feature, you can have back directly the output like dotenv package using the config method.

// Inline
const output = require("dotenv-mono").config(/* config */);

// Using the function
const {dotenvConfig} = require("dotenv-mono");
const output = dotenvConfig(/* config */);

// Use `.dotenv.server` or `.dotenv.server.local`, etc...
load({extension: "server"});

// You can specify the file path
load({path: "../../configs/.env"});

load({expand: false});

load({defaults: ".env.def"});

// If `.dotenv.overwrite` is present use it with max priority
load({
	priorities: {
		".env.overwrite": 100,
	},
});

const dotenv = require("dotenv-mono").load();
dotenv.save({"MY_ENV_1": "enjoy"});

// Without loading into the working process
const {Dotenv} = require("dotenv-mono");
const dotenv = new Dotenv();
dotenv.loadFile(); // Skip loading into the process
dotenv.save({
	"MY_ENV_1": "enjoy",
	"MY_ENV_2": "'enjoy quotes'",
	"MY_ENV_3": 999,
});

As on the dotenv package on the CLI/Console, you can use the --require (-r) command line option to preload dotenv. By doing this, you do not need to require and load dotenv in your application code.

$ node -r dotenv-mono/load your_script.js

The configuration options below are supported as command line arguments in the format dotenv_config_<option>=value

$ node -r dotenv-mono/load your_script.js dotenv_config_path=/custom/path/to/.env dotenv_config_debug=true

Additionally, you can use environment variables to set configuration options. Command line arguments will precede these.

$ DOTENV_CONFIG_<OPTION>=value node -r dotenv-mono/load your_script.js

$ DOTENV_CONFIG_ENCODING=latin1 DOTENV_CONFIG_DEBUG=true node -r dotenv-mono/load your_script.js dotenv_config_path=/custom/path/to/.env

It will read your .env file following the criteria, parse the contents, assign it to process.env.

Note: This method differs from the previous load function. In that it requires the configuration to be loaded on the class instance via the constructor.

public load(loadOnProcess: boolean): Dotenv;

It will read your .env file following the criteria, parse the contents, ready to be read or changed programmatically.

public loadFile(): Dotenv;

Merge the data on input with the loaded data from load or loadFile, and save the changes on the original dotenv file.

Note: If .env.defaults is present, it won't be overwritten, you can just save the changes on the main dotenv file (.env, .env.local, etc...)

public save(changes: Record<string, any>): Dotenv;

See the dotenv documentation HERE

public parse<T extends Record<string, any> = Record<string, any>>(src: string | Buffer): T;

Have an idea? Found a bug? Please raise to ISSUES or PULL REQUEST. Contributions are welcome and are greatly appreciated! Every little bit helps, and credit will always be given.