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
Usage
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
})
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. 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
Config
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
.
Options
Path
Default: path.resolve(process.cwd(), '.env')
You can specify a custom path if your file containing environment variables is named or located differently.
require('dotenv').config({path: '/full/custom/path/to/your/env/vars'})
Encoding
Default: utf8
You may specify the encoding of your file containing environment variables using this option.
require('dotenv').config({encoding: 'base64'})
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 = new Buffer('BASIC=basic')
const config = dotenv.parse(buf) // will return an object
console.log(typeof config, config) // object { BASIC : 'basic' }
Rules
The parsing engine currently supports the following rules:
BASIC=basic
becomes{BASIC: 'basic'}
- empty lines are skipped
- lines beginning with
#
are treated as comments - empty values become empty strings (
EMPTY=
becomes{EMPTY: ''}
) - single and double quoted values are escaped (
SINGLE_QUOTE='quoted'
becomes{SINGLE_QUOTE: "quoted"}
) - new lines are expanded if in double quotes (
MULTILINE="new\nline"
becomes
{MULTILINE: 'new
line'}
- inner quotes are maintained (think JSON) (
JSON={"foo": "bar"}
becomes{JSON:"{\"foo\": \"bar\"}"
) - whitespace is removed from both ends of the value (see more on
trim
) (FOO=" some value "
becomes{FOO: 'some value'}
)
FAQ
.env
file?
Should I commit my 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?
Should I have multiple 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.
What happens to environment variables that were already set?
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 (var k in envConfig) {
process.env[k] = envConfig[k]
}
Can I customize/write plugins for dotenv?
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:
var dotenv = require('dotenv')
var variableExpansion = require('dotenv-expand')
const myEnv = dotenv.config()
variableExpansion(myEnv)
What about variable expansion?
For dotenv@2.x.x
: Use dotenv-expand.
For dotenv@1.x.x
: We haven't been presented with a compelling use case for expanding variables and believe it leads to env vars that are not "fully orthogonal" as The Twelve-Factor App outlines.[1][2] Please open an issue if you have a compelling use case.
import
?
How do I use dotenv with 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'
dotenv.config()
import errorReporter from './errorReporter'
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.
- Preload dotenv:
node --require dotenv/config index.js
(Note: you do not need toimport
dotenv with this approach) - Import
dotenv/config
instead ofdotenv
(Note: you do not need to calldotenv.config()
and must pass options via the command line with this approach) - Create a separate file that will execute
config
first as outlined in this comment on #133
Contributing Guide
See CONTRIBUTING.md
Change Log
See CHANGELOG.md
License
See LICENSE
Who's using dotenv
Here's just a few of many repositories using dotenv:
Go well with dotenv
Here's some projects that expand on dotenv. Check them out.