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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.
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 });
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 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 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`.
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.
# with npm
npm install dotenv
# or with Yarn
yarn add dotenv
As early as possible in your application, require and configure dotenv.
require('dotenv').config()
Create a .env
file in the root directory of your project. Add
environment-specific variables on new lines in the form of NAME=VALUE
.
For example:
DB_HOST=localhost
DB_USER=root
DB_PASS=s1mpl3
That's it.
process.env
now has the keys and values you defined in your .env
file.
const db = require('db')
db.connect({
host: process.env.DB_HOST,
username: process.env.DB_USER,
password: process.env.DB_PASS
})
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. This is the preferred approach when using import
instead of require
.
$ 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/your/env/vars
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=base64 node -r dotenv/config your_script.js dotenv_config_path=/custom/path/to/.env
Alias: load
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
.
Default: path.resolve(process.cwd(), '.env')
You may specify a custom path if your file containing environment variables is located elsewhere.
require('dotenv').config({ path: '/full/custom/path/to/your/env/vars' })
Default: utf8
You may specify the encoding of your file containing environment variables.
require('dotenv').config({ encoding: 'base64' })
Default: false
You may 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 })
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' }
Default: false
You may 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
The parsing engine currently supports the following rules:
BASIC=basic
becomes {BASIC: 'basic'}
#
are treated as commentsEMPTY=
becomes {EMPTY: ''}
)SINGLE_QUOTE='quoted'
becomes {SINGLE_QUOTE: "quoted"}
)MULTILINE="new\nline"
becomes{MULTILINE: 'new
line'}
JSON={"foo": "bar"}
becomes {JSON:"{\"foo\": \"bar\"}"
)trim
) (FOO=" some value "
becomes {FOO: 'some value'}
).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.
.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.
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. This behavior allows you to override all .env
configurations with a machine-specific environment, although it is not recommended.
If you want to override process.env
you can do something like this:
const fs = require('fs')
const dotenv = require('dotenv')
const envConfig = dotenv.parse(fs.readFileSync('.env.override'))
for (let k in envConfig) {
process.env[k] = envConfig[k]
}
For dotenv@2.x.x
: Yes. dotenv.config()
now 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)
Try dotenv-expand
import
?ES2015 and beyond offers modules that allow you to export
any top-level function
, class
, var
, let
, or const
.
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.
You must run dotenv.config()
before referencing any environment variables. Here's an example of problematic code:
errorReporter.js
:
import { Client } from 'best-error-reporting-service'
export const client = new Client(process.env.BEST_API_KEY)
index.js
:
import dotenv from 'dotenv'
import errorReporter from './errorReporter'
dotenv.config()
errorReporter.client.report(new Error('faq example'))
client
will not be configured correctly because it was constructed before dotenv.config()
was executed. There are (at least) 3 ways to make this work.
node --require dotenv/config index.js
(Note: you do not need to import
dotenv with this approach)dotenv/config
instead of dotenv
(Note: you do not need to call dotenv.config()
and must pass options via the command line with this approach)config
first as outlined in this comment on #133See CONTRIBUTING.md
See CHANGELOG.md
See LICENSE
Here's just a few of many repositories using dotenv:
Here's some projects that expand on dotenv. Check them out.
FAQs
Loads environment variables from .env file
We found that dotenv demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 4 open source maintainers collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
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