dotenv
Last updated
Last updated
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.
As early as possible in your application, require and configure dotenv.
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:
process.env
now has the keys and values you defined in your .env
file.
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
.
The configuration options below are supported as command line arguments in the format dotenv_config_<option>=value
Additionally, you can use environment variables to set configuration options. Command line arguments will precede these.
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.
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.
Default: utf8
You may specify the encoding of your file containing environment variables.
Default: false
You may turn on logging to help debug why certain keys or values are not being set as you expect.
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.
Default: false
You may turn on logging to help debug why certain keys or values are not being set as you expect.
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: ''}
)
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
.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:
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:
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
:
index.js
:
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 to import
dotenv with this approach)
Import dotenv/config
instead of dotenv
(Note: you do not need to call dotenv.config()
and must pass options via the command line or environment variables with this approach)
Create a separate file that will execute config
first as outlined in this comment on #133
See CONTRIBUTING.md
See CHANGELOG.md
These npm modules depend on it.
Projects that expand it often use the keyword "dotenv" on npm.