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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

npm install dotenv --save

You can also use an npm-compatible package manager like yarn, bun or pnpm:

yarn add dotenv

bun add dotenv

pnpm add dotenv

🏗️ Usage

Create a .env file in the root of your project (if using a monorepo structure like apps/backend/app.js, put it in the root of the folder where your app.js process runs):

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'

ES6 import if you need to set config options:

import dotenv from 'dotenv'

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

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

require('dotenv').config()
// or import 'dotenv/config' if you're using ES6

...

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

Note: Consider using dotenvx instead of preloading. I am now doing (and recommending) so.

It serves the same purpose (you do not need to require and load dotenv), adds better debugging, and works with ANY language, framework, or platform. – motdotla

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

Use dotenvx to use variable expansion.

Reference and expand variables already on your machine for use in your .env file.

# .env
USERNAME="username"
DATABASE_URL="postgres://${USERNAME}@localhost/my_database"

// index.js
console.log('DATABASE_URL', process.env.DATABASE_URL)

$ dotenvx run --debug -- node index.js
[dotenvx@0.14.1] injecting env (2) from .env
DATABASE_URL postgres://username@localhost/my_database

Command Substitution

Use dotenvx to use command substitution.

Add the output of a command to one of your variables in your .env file.

# .env
DATABASE_URL="postgres://$(whoami)@localhost/my_database"

// index.js
console.log('DATABASE_URL', process.env.DATABASE_URL)

$ dotenvx run --debug -- node index.js
[dotenvx@0.14.1] injecting env (1) from .env
DATABASE_URL postgres://yourusername@localhost/my_database

Syncing

You need to keep .env files in sync between machines, environments, or team members? Use dotenvx to encrypt your .env files and safely include them in source control. This still subscribes to the twelve-factor app rules by generating a decryption key separate from code.

Multiple Environments

Use dotenvx to generate .env.ci, .env.production files, and more.

Deploying

You need to deploy your secrets in a cloud-agnostic manner? Use dotenvx to generate a private decryption key that is set on your production server.

🌴 Manage Multiple Environments

Use dotenvx

Run any environment locally. Create a .env.ENVIRONMENT file and use --env-file to load it. It's straightforward, yet flexible.

$ echo "HELLO=production" > .env.production
$ echo "console.log('Hello ' + process.env.HELLO)" > index.js

$ dotenvx run --env-file=.env.production -- node index.js
Hello production
> ^^

or with multiple .env files

$ echo "HELLO=local" > .env.local
$ echo "HELLO=World" > .env
$ echo "console.log('Hello ' + process.env.HELLO)" > index.js

$ dotenvx run --env-file=.env.local --env-file=.env -- node index.js
Hello local

more environment examples

🚀 Deploying

Use dotenvx.

Add encryption to your .env files with a single command. Pass the --encrypt flag.

$ dotenvx set HELLO Production --encrypt -f .env.production
$ echo "console.log('Hello ' + process.env.HELLO)" > index.js

$ DOTENV_PRIVATE_KEY_PRODUCTION="<.env.production private key>" dotenvx run -- node index.js
[dotenvx] injecting env (2) from .env.production
Hello Production

learn more

📚 Examples

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

📖 Documentation

Dotenv exposes four functions:

config
parse
populate

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' })

By default, config will look for a file called .env in the current working directory.

Pass in multiple files as an array, and they will be parsed in order and combined with process.env (or option.processEnv, if set). The first value set for a variable will win, unless the options.override flag is set, in which case the last value set will win. If a value already exists in process.env and the options.override flag is NOT set, no changes will be made to that value.

require('dotenv').config({ path: ['.env.local', '.env'] })

quiet

Default: false

Suppress runtime logging message.

// index.js
require('dotenv').config({ quiet: false }) // change to true to suppress
console.log(`Hello ${process.env.HELLO}`)

# .env
.env

$ node index.js
[dotenv@17.0.0] injecting env (1) from .env
Hello World

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(s). If multiple files have been provided in option.path the override will also be used as each file is combined with the next. Without override being set, the first value wins. With override set the last value wins.

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

processEnv

Default: process.env

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

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

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

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.

❓ 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?

We recommend creating one .env file per environment. Use .env for local/development, .env.production for production and so on. This still follows the twelve factor principles as each is attributed individually to its own environment. Avoid custom set ups that work in inheritance somehow (.env.production inherits values form .env for example). It is better to duplicate values if necessary across each .env.environment file.

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:

class Client {
  constructor (apiKey) {
    console.log('apiKey', apiKey)

    this.apiKey = apiKey
  }
}

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' // process.env.API_KEY will be blank!

process.env.API_KEY will be blank.

Instead, index.mjs should be written as..

import 'dotenv/config'

import errorReporter from './errorReporter.mjs'

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:

Preload with dotenvx: dotenvx run -- node index.js (Note: you do not need to import dotenv with this approach)
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 dotenvx to unlock syncing encrypted .env files over git.

What if I accidentally commit my `.env` file to code?

Remove it, remove git history and then install the git pre-commit hook to prevent this from ever happening again.

brew install dotenvx/brew/dotenvx
dotenvx precommit --install

How can I prevent committing my `.env` file to a Docker build?

Use the docker prebuild hook.

# Dockerfile
...
RUN curl -fsS https://dotenvx.sh/ | sh
...
RUN dotenvx prebuild
CMD ["dotenvx", "run", "--", "node", "index.js"]

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.