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---

Dotenv-expand adds variable expansion on top of dotenv. If you find yourself needing to expand environment variables already existing on your machine, then dotenv-expand is your tool.

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

Or installing with yarn? yarn add dotenv-expand

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

PASSWORD="s1mpl3"
DB_PASS=$PASSWORD

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

var dotenv = require('dotenv')
var dotenvExpand = require('dotenv-expand')

var myEnv = dotenv.config({ processEnv: {} }) // important to set processEnv: {}, otherwise expansion will be attempted on your already existing machine envs
dotenvExpand.expand(myEnv)

console.log(process.env)

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

You can use the --require (-r) command line option to preload dotenv & dotenv-expand. By doing this, you do not need to require and load dotenv or dotenv-expand in your application code. This is the preferred approach when using import instead of require.

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

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

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

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

See tests/.env for simple and complex examples of variable expansion in your .env file.

DotenvExpand exposes one function:

• expand

expand will expand your environment variables.

const dotenv = {
  parsed: {
    BASIC: 'basic',
    BASIC_EXPAND: '${BASIC}',
    BASIC_EXPAND_SIMPLE: '$BASIC'
  }
}

const obj = dotenvExpand.expand(dotenv)

console.log(obj)

Default: process.env

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

const myObject = {}
const dotenv = {
  processEnv: myObject,
  parsed: {
    SHOULD_NOT_EXIST: 'testing'
  }
}
const obj = dotenvExpand.expand(dotenv).parsed

console.log(obj.SHOULD_NOT_EXIST) // testing
console.log(myObject.SHOULD_NOT_EXIST) // testing
console.log(process.env.SHOULD_NOT_EXIST) // undefined

The expansion engine roughly has the following rules:

• $KEY will expand any env with the name KEY
• ${KEY} will expand any env with the name KEY
• \$KEY will escape the $KEY rather than expand
• ${KEY:-default} will first attempt to expand any env with the name KEY. If not one, then it will return default

You can see a full list of examples here.

See CONTRIBUTING.md

See CHANGELOG.md

These npm modules depend on it.