Current File : //usr/lib/node_modules/npm/node_modules/dotenv/README.md
# dotenv
<img src="https://raw.githubusercontent.com/motdotla/dotenv/master/dotenv.png" alt="dotenv" align="right" />
Dotenv is a zero-dependency module that loads environment variables from a `.env` file into [`process.env`](https://nodejs.org/docs/latest/api/process.html#process_process_env). Storing configuration in the environment separate from code is based on [The Twelve-Factor App](http://12factor.net/config) methodology.
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## Install
```bash
npm install dotenv --save
```
## Usage
As early as possible in your application, require and configure dotenv.
```javascript
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:
```dosini
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.
```javascript
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`.
```bash
$ node -r dotenv/config your_script.js
```
The configuration options below are supported as command line arguments in the format `dotenv_config_<option>=value`
```bash
$ 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`](https://nodejs.org/docs/latest/api/process.html#process_process_env),
and return an Object with a `parsed` key containing the loaded content or an `error` key if it failed.
```js
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.
```js
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.
```js
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.
```js
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`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim)) (`FOO=" some value "` becomes `{FOO: 'some value'}`)
## FAQ
### 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?
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.
>
> – [The Twelve-Factor App](http://12factor.net/config)
### 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:
```javascript
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:
```js
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](https://github.com/motdotla/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](http://12factor.net/config) outlines.<sup>[[1](https://github.com/motdotla/dotenv/issues/39)][[2](https://github.com/motdotla/dotenv/pull/97)]</sup> Please open an issue if you have a compelling use case.
### How do I use dotenv with `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.
>
> – [ES6 In Depth: Modules](https://hacks.mozilla.org/2015/08/es6-in-depth-modules/)
You must run `dotenv.config()` before referencing any environment variables. Here's an example of problematic code:
`errorReporter.js`:
```js
import { Client } from 'best-error-reporting-service'
export const client = new Client(process.env.BEST_API_KEY)
```
`index.js`:
```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.
1. Preload dotenv: `node --require dotenv/config index.js` (_Note: you do not need to `import` dotenv with this approach_)
2. Import `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_)
3. Create a separate file that will execute `config` first as outlined in [this comment on #133](https://github.com/motdotla/dotenv/issues/133#issuecomment-255298822)
## Contributing Guide
See [CONTRIBUTING.md](CONTRIBUTING.md)
## Change Log
See [CHANGELOG.md](CHANGELOG.md)
## License
See [LICENSE](LICENSE)
## Who's using dotenv
Here's just a few of many repositories using dotenv:
* [jaws](https://github.com/jaws-framework/jaws-core-js)
* [node-lambda](https://github.com/motdotla/node-lambda)
* [resume-cli](https://www.npmjs.com/package/resume-cli)
* [phant](https://www.npmjs.com/package/phant)
* [adafruit-io-node](https://github.com/adafruit/adafruit-io-node)
* [mockbin](https://www.npmjs.com/package/mockbin)
* [and many more...](https://www.npmjs.com/browse/depended/dotenv)
## Go well with dotenv
Here's some projects that expand on dotenv. Check them out.
* [require-environment-variables](https://github.com/bjoshuanoah/require-environment-variables)
* [dotenv-safe](https://github.com/rolodato/dotenv-safe)
* [envalid](https://github.com/af/envalid)
* [lookenv](https://github.com/RodrigoEspinosa/lookenv)
* [run.env](https://www.npmjs.com/package/run.env)
* [dotenv-webpack](https://github.com/mrsteele/dotenv-webpack)
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