dotenv

What is dotenv?

The dotenv npm package is used to load environment variables from a .env file into process.env, providing a convenient way to configure your application's environment during development. It helps in managing sensitive credentials and configuration options by keeping them out of the codebase.

What are dotenv's main functionalities?

Basic Configuration

This is the simplest use case for dotenv. By calling `require('dotenv').config();`, dotenv reads the .env file, parses the contents, and loads them into `process.env`. After this, environment variables can be accessed using `process.env.VAR_NAME`.

require('dotenv').config();

Custom Path

If your .env file is not located in the root directory or you have multiple .env files, you can specify a custom path to your .env file using the `path` option.

require('dotenv').config({ path: '/custom/path/to/.env' });

Debugging

To assist in debugging, you can enable debug output by setting the `debug` option to `true`. This will log any errors to the console while reading the .env file.

require('dotenv').config({ debug: process.env.DEBUG });

Other packages similar to dotenv

dotenv-expand

dotenv-expand is an extension for dotenv. It allows you to have environment variables in your .env file that reference other environment variables, similar to variable expansion in Unix shell scripts. It's useful when you need to reduce redundancy in your .env files.

cross-env

cross-env allows you to set and use environment variables across platforms without worrying about platform-specific differences in how environment variables are set. Unlike dotenv, which is focused on loading variables from a file, cross-env is more about providing scripts with environment variables in a cross-platform way.

env-cmd

env-cmd is another npm package that allows you to specify a file containing environment variable definitions and then run a given command using those variables. It's similar to dotenv but is more focused on injecting environment variables into the command line for scripts, rather than loading them into `process.env`.

README

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---

dotenv

Dotenv is a zero-dependency module that loads environment variables from a .env file into process.env. Storing configuration in the environment separate from code is based on The Twelve-Factor App methodology.

• 🌱 Install
• 🏗️ Usage (.env)
• 🚀 Deploying (.env.vault) 🆕
• 🌴 Multiple Environments 🆕
• 📚 Examples
• 📖 Docs
• ❓ FAQ
• ⏱️ Changelog

🌱 Install

# install locally (recommended)
npm install dotenv --save

Or installing with yarn? yarn add dotenv

🏗️ Usage

Create a .env file in the root of your project:

S3_BUCKET="YOURS3BUCKET"
SECRET_KEY="YOURSECRETKEYGOESHERE"

As early as possible in your application, import and configure dotenv:

require('dotenv').config()
console.log(process.env) // remove this after you've confirmed it is working

.. or using ES6?

import 'dotenv/config'

That's it. process.env now has the keys and values you defined in your .env file:

require('dotenv').config()

...

s3.getBucketCors({Bucket: process.env.S3_BUCKET}, function(err, data) {})

Multiline values

If you need multiline variables, for example private keys, those are now supported (>= v15.0.0) with line breaks:

PRIVATE_KEY="-----BEGIN RSA PRIVATE KEY-----
...
Kh9NV...
...
-----END RSA PRIVATE KEY-----"

Alternatively, you can double quote strings and use the \n character:

PRIVATE_KEY="-----BEGIN RSA PRIVATE KEY-----\nKh9NV...\n-----END RSA PRIVATE KEY-----\n"

Comments

Comments may be added to your file on their own line or inline:

# This is a comment
SECRET_KEY=YOURSECRETKEYGOESHERE # comment
SECRET_HASH="something-with-a-#-hash"

Comments begin where a # exists, so if your value contains a # please wrap it in quotes. This is a breaking change from >= v15.0.0 and on.

Parsing

The engine which parses the contents of your file containing environment variables is available to use. It accepts a String or Buffer and will return an Object with the parsed keys and values.

const dotenv = require('dotenv')
const buf = Buffer.from('BASIC=basic')
const config = dotenv.parse(buf) // will return an object
console.log(typeof config, config) // object { BASIC : 'basic' }

Preload

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/config your_script.js

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

$ node -r dotenv/config 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/config your_script.js

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

Variable Expansion

You need to add the value of another variable in one of your variables? Use dotenv-expand.

Syncing

You need to keep .env files in sync between machines, environments, or team members? Use dotenv-vault.

Deploying

You need to deploy your secrets in a cloud-agnostic manner? Use a .env.vault file.

Multiple Environments

You need to manage your secrets across different environments and apply them as needed? Use a .env.vault file with a DOTENV_KEY.

🚀 Deploying

Note: Requires dotenv >= 16.1.0

Encrypt your .env.vault file.

$ npx dotenv-vault build

Fetch your production DOTENV_KEY.

$ npx dotenv-vault keys production

Set DOTENV_KEY on your server.

# heroku example
heroku config:set DOTENV_KEY=dotenv://:key_1234…@dotenv.org/vault/.env.vault?environment=production

That's it! On deploy, your .env.vault file will be decrypted and its secrets injected as environment variables – just in time.

ℹ️ A note from Mot: Until recently, we did not have an opinion on how and where to store your secrets in production. We now strongly recommend generating a .env.vault file. It's the best way to prevent your secrets from being scattered across multiple servers and cloud providers – protecting you from breaches like the CircleCI breach. Also it unlocks interoperability WITHOUT native third-party integrations. Third-party integrations are increasingly risky to our industry. They may be the 'du jour' of today, but we imagine a better future.

Learn more at dotenv-vault: Deploying

🌴 Manage Multiple Environments

Edit your production environment variables.

$ npx dotenv-vault open production

Regenerate your .env.vault file.

$ npx dotenv-vault build

ℹ️ 🔐 Vault Managed vs 💻 Locally Managed: The above example, for brevity's sake, used the 🔐 Vault Managed solution to manage your .env.vault file. You can instead use the 💻 Locally Managed solution. Read more here. Our vision is that other platforms and orchestration tools adopt the .env.vault standard as they did the .env standard. We don't expect to be the only ones providing tooling to manage and generate .env.vault files.

Learn more at dotenv-vault: Manage Multiple Environments

📚 Examples

See examples of using dotenv with various frameworks, languages, and configurations.

• nodejs
• nodejs (debug on)
• nodejs (override on)
• nodejs (processEnv override)
• esm
• esm (preload)
• typescript
• typescript parse
• typescript config
• webpack
• webpack (plugin)
• react
• react (typescript)
• express
• nestjs
• fastify

📖 Documentation

Dotenv exposes four functions:

• config
• parse
• populate
• decrypt

Config

config will read your .env file, parse the contents, assign it to process.env, and return an Object with a parsed key containing the loaded content or an error key if it failed.

const result = dotenv.config()

if (result.error) {
  throw result.error
}

console.log(result.parsed)

You can additionally, pass options to config.

Options

path

Default: path.resolve(process.cwd(), '.env')

Specify a custom path if your file containing environment variables is located elsewhere.

require('dotenv').config({ path: '/custom/path/to/.env' })

encoding

Default: utf8

Specify the encoding of your file containing environment variables.

require('dotenv').config({ encoding: 'latin1' })

debug

Default: false

Turn on logging to help debug why certain keys or values are not being set as you expect.

require('dotenv').config({ debug: process.env.DEBUG })

override

Default: false

Override any environment variables that have already been set on your machine with values from your .env file.

require('dotenv').config({ override: true })

processEnv

Default: process.env

Specify an object to write your secrets to. Defaults to process.env environment variables.

const myObject = {}
require('dotenv').config({ processEnv: myObject })

console.log(myObject) // values from .env or .env.vault live here now.
console.log(process.env) // this was not changed or written to

DOTENV_KEY

Default: process.env.DOTENV_KEY

Pass the DOTENV_KEY directly to config options. Defaults to looking for process.env.DOTENV_KEY environment variable. Note this only applies to decrypting .env.vault files. If passed as null or undefined, or not passed at all, dotenv falls back to its traditional job of parsing a .env file.

require('dotenv').config({ DOTENV_KEY: 'dotenv://:key_1234…@dotenv.org/vault/.env.vault?environment=production' })

Parse

The engine which parses the contents of your file containing environment variables is available to use. It accepts a String or Buffer and will return an Object with the parsed keys and values.

const dotenv = require('dotenv')
const buf = Buffer.from('BASIC=basic')
const config = dotenv.parse(buf) // will return an object
console.log(typeof config, config) // object { BASIC : 'basic' }

Options

debug

Default: false

Turn on logging to help debug why certain keys or values are not being set as you expect.

const dotenv = require('dotenv')
const buf = Buffer.from('hello world')
const opt = { debug: true }
const config = dotenv.parse(buf, opt)
// expect a debug message because the buffer is not in KEY=VAL form

Populate

The engine which populates the contents of your .env file to process.env is available for use. It accepts a target, a source, and options. This is useful for power users who want to supply their own objects.

For example, customizing the source:

const dotenv = require('dotenv')
const parsed = { HELLO: 'world' }

dotenv.populate(process.env, parsed)

console.log(process.env.HELLO) // world

For example, customizing the source AND target:

const dotenv = require('dotenv')
const parsed = { HELLO: 'universe' }
const target = { HELLO: 'world' } // empty object

dotenv.populate(target, parsed, { override: true, debug: true })

console.log(target) // { HELLO: 'universe' }

options

Debug

Default: false

Turn on logging to help debug why certain keys or values are not being populated as you expect.

override

Default: false

Override any environment variables that have already been set.

Decrypt

The engine which decrypts the ciphertext contents of your .env.vault file is available for use. It accepts a ciphertext and a decryption key. It uses AES-256-GCM encryption.

For example, decrypting a simple ciphertext:

const dotenv = require('dotenv')
const ciphertext = 's7NYXa809k/bVSPwIAmJhPJmEGTtU0hG58hOZy7I0ix6y5HP8LsHBsZCYC/gw5DDFy5DgOcyd18R'
const decryptionKey = 'ddcaa26504cd70a6fef9801901c3981538563a1767c297cb8416e8a38c62fe00'

const decrypted = dotenv.decrypt(ciphertext, decryptionKey)

console.log(decrypted) // # development@v6\nALPHA="zeta"

❓ FAQ

Why is the .env file not loading my environment variables successfully?

Most likely your .env file is not in the correct place. See this stack overflow.

Turn on debug mode and try again..

require('dotenv').config({ debug: true })

You will receive a helpful error outputted to your console.

Should I commit my .env file?

No. We strongly recommend against committing your .env file to version control. It should only include environment-specific values such as database passwords or API keys. Your production database should have a different password than your development database.

Should I have multiple .env files?

No. We strongly recommend against having a "main" .env file and an "environment" .env file like .env.test. Your config should vary between deploys, and you should not be sharing values between environments.

In a twelve-factor app, env vars are granular controls, each fully orthogonal to other env vars. They are never grouped together as “environments”, but instead are independently managed for each deploy. This is a model that scales up smoothly as the app naturally expands into more deploys over its lifetime.

– The Twelve-Factor App

What rules does the parsing engine follow?

The parsing engine currently supports the following rules:

• BASIC=basic becomes {BASIC: 'basic'}
• empty lines are skipped
• lines beginning with # are treated as comments
• # marks the beginning of a comment (unless when the value is wrapped in quotes)
• empty values become empty strings (EMPTY= becomes {EMPTY: ''})
• inner quotes are maintained (think JSON) (JSON={"foo": "bar"} becomes {JSON:"{\"foo\": \"bar\"}")
• whitespace is removed from both ends of unquoted values (see more on trim) (FOO= some value becomes {FOO: 'some value'})
• single and double quoted values are escaped (SINGLE_QUOTE='quoted' becomes {SINGLE_QUOTE: "quoted"})
• single and double quoted values maintain whitespace from both ends (FOO=" some value " becomes {FOO: ' some value '})
• double quoted values expand new lines (MULTILINE="new\nline" becomes

{MULTILINE: 'new
line'}

• backticks are supported (BACKTICK_KEY=`This has 'single' and "double" quotes inside of it.`)

What happens to environment variables that were already set?

By default, we will never modify any environment variables that have already been set. In particular, if there is a variable in your .env file which collides with one that already exists in your environment, then that variable will be skipped.

If instead, you want to override process.env use the override option.

require('dotenv').config({ override: true })

How come my environment variables are not showing up for React?

Your React code is run in Webpack, where the fs module or even the process global itself are not accessible out-of-the-box. process.env can only be injected through Webpack configuration.

If you are using react-scripts, which is distributed through create-react-app, it has dotenv built in but with a quirk. Preface your environment variables with REACT_APP_. See this stack overflow for more details.

If you are using other frameworks (e.g. Next.js, Gatsby...), you need to consult their documentation for how to inject environment variables into the client.

Can I customize/write plugins for dotenv?

Yes! dotenv.config() returns an object representing the parsed .env file. This gives you everything you need to continue setting values on process.env. For example:

const dotenv = require('dotenv')
const variableExpansion = require('dotenv-expand')
const myEnv = dotenv.config()
variableExpansion(myEnv)

How do I use dotenv with import?

Simply..

// index.mjs (ESM)
import 'dotenv/config' // see https://github.com/motdotla/dotenv#how-do-i-use-dotenv-with-import
import express from 'express'

A little background..

When you run a module containing an import declaration, the modules it imports are loaded first, then each module body is executed in a depth-first traversal of the dependency graph, avoiding cycles by skipping anything already executed.

– ES6 In Depth: Modules

What does this mean in plain language? It means you would think the following would work but it won't.

errorReporter.mjs:

import { Client } from 'best-error-reporting-service'

export default new Client(process.env.API_KEY)

index.mjs:

// Note: this is INCORRECT and will not work
import * as dotenv from 'dotenv'
dotenv.config()

import errorReporter from './errorReporter.mjs'
errorReporter.report(new Error('documented example'))

process.env.API_KEY will be blank.

Instead, index.mjs should be written as..

import 'dotenv/config'

import errorReporter from './errorReporter.mjs'
errorReporter.report(new Error('documented example'))

Does that make sense? It's a bit unintuitive, but it is how importing of ES6 modules work. Here is a working example of this pitfall.

There are two alternatives to this approach:

1. Preload dotenv: node --require dotenv/config index.js (Note: you do not need to import dotenv with this approach)
2. Create a separate file that will execute config first as outlined in this comment on #133

Why am I getting the error Module not found: Error: Can't resolve 'crypto|os|path'?

You are using dotenv on the front-end and have not included a polyfill. Webpack < 5 used to include these for you. Do the following:

npm install node-polyfill-webpack-plugin

Configure your webpack.config.js to something like the following.

require('dotenv').config()

const path = require('path');
const webpack = require('webpack')

const NodePolyfillPlugin = require('node-polyfill-webpack-plugin')

module.exports = {
  mode: 'development',
  entry: './src/index.ts',
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist'),
  },
  plugins: [
    new NodePolyfillPlugin(),
    new webpack.DefinePlugin({
      'process.env': {
        HELLO: JSON.stringify(process.env.HELLO)
      }
    }),
  ]
};

Alternatively, just use dotenv-webpack which does this and more behind the scenes for you.

What about variable expansion?

Try dotenv-expand

What about syncing and securing .env files?

Use dotenv-vault

What is a .env.vault file?

A .env.vault file is an encrypted version of your development (and ci, staging, production, etc) environment variables. It is paired with a DOTENV_KEY to deploy your secrets more securely than scattering them across multiple platforms and tools. Use dotenv-vault to manage and generate them.

Contributing Guide

See CONTRIBUTING.md

CHANGELOG

See CHANGELOG.md

Who's using dotenv?

These npm modules depend on it.

Projects that expand it often use the keyword "dotenv" on npm.

Changelog

16.3.0 (2023-06-16)

Added

• Optionally pass DOTENV_KEY to options rather than relying on process.env.DOTENV_KEY. Defaults to process.env.DOTENV_KEY #754