react-native-dotenv

What is react-native-dotenv?

The react-native-dotenv package is used to load environment variables from a .env file into a React Native application. This allows developers to manage configuration settings and sensitive information like API keys, database URLs, and other environment-specific variables in a secure and organized manner.

What are react-native-dotenv's main functionalities?

Loading Environment Variables

This feature allows you to load environment variables from a .env file into your React Native application. By importing the variables using the @env module, you can access them throughout your application.

import { API_URL } from '@env';

console.log(API_URL);

Customizing Environment Variable Prefix

You can customize the prefix for environment variables to avoid conflicts. By default, the package uses the @env prefix, but you can change it to something else if needed.

import { API_URL } from '@env';

console.log(API_URL);

TypeScript Support

The package provides TypeScript support, allowing you to declare the types of your environment variables. This helps in maintaining type safety and avoiding runtime errors.

declare module '@env' {
  export const API_URL: string;
  export const OTHER_ENV_VAR: string;
}

Other packages similar to react-native-dotenv

react-native-config

react-native-config is another popular package for managing environment variables in React Native applications. It allows you to define different environment configurations and access them in your code. Compared to react-native-dotenv, react-native-config offers more advanced features like multiple environment support and integration with native code.

dotenv

dotenv is a widely-used package for loading environment variables from a .env file into Node.js applications. While it is not specifically designed for React Native, it can be used in conjunction with other tools to achieve similar functionality. Compared to react-native-dotenv, dotenv is more general-purpose and lacks some of the React Native-specific features.

README

react-native-dotenv

Load environment variables using import statements.

Installation

$ npm install react-native-dotenv

Breaking changes: moving from v0.x to v2.x changes both the setup and usage of this package. Please see the migration guide.

Many have been asking about the reasons behind recent changes in this repo. Please see the story wiki page.

Introduction

This babel plugin lets you inject your environment variables into your react-native environment using dotenv for multiple environments.

Usage

.babelrc

Basic setup:

{
  "plugins": [
    ["module:react-native-dotenv"]
  ]
}

If the defaults do not cut it for your project, this outlines the available options for your Babel configuration and their respective default values, but you do not need to add them if you are using the default settings.

{
  "plugins": [
    ["module:react-native-dotenv", {
      "moduleName": "@env",
      "path": ".env",
      "blacklist": null,
      "whitelist": null,
      "safe": false,
      "allowUndefined": true
    }]
  ]
}

Note: for safe mode, it's highly recommended to set allowUndefined to false.

.env

API_URL=https://api.example.org
API_TOKEN=abc123

In users.js

import {API_URL, API_TOKEN} from "@env"

fetch(`${API_URL}/users`, {
  headers: {
    'Authorization': `Bearer ${API_TOKEN}`
  }
})

White and black lists

It is possible to limit the scope of env variables that will be imported by specifying a whitelist and/or a blacklist as an array of strings.

{
  "plugins": [
    ["module:react-native-dotenv", {
      "blacklist": [
        "GITHUB_TOKEN"
      ]
    }]
  ]
}

{
  "plugins": [
    ["module:react-native-dotenv", {
      "whitelist": [
        "API_URL",
        "API_TOKEN"
      ]
    }]
  ]
}

Safe mode

Enable safe mode to only allow environment variables defined in the .env file. This will completely ignore everything that is already defined in the environment.

The .env file has to exist.

{
  "plugins": [
    ["module:react-native-dotenv", {
      "safe": true
    }]
  ]
}

Allow undefined

Allow importing undefined variables, their value will be undefined.

{
  "plugins": [
    ["module:react-native-dotenv", {
      "allowUndefined": true
    }]
  ]
}

import {UNDEFINED_VAR} from '@env'

console.log(UNDEFINED_VAR === undefined) // true

When set to false, an error will be thrown. This is no longer default behavior.

Multi-env

This package now supports environment specific variables. This means you may now import environment variables from multiple files, i.e. .env, .env.development, .env.production, and .env.test.

Note: it is not recommended that you commit any sensitive information in .env file to code in case your git repo is exposed. The best practice is to put a .env.template or .env.development.template that contains dummy values so other developers know what to configure. Then add your .env and .env.development to .gitignore. In a future release you can keep sensitive keys in a separate .env.local (and respective .env.local.template) in .gitignore and you can use your other .env files for non-sensitive config.

The base set of variables will be .env and the environment-specific variables will overwrite them.

The variables will automatically be pulled from the appropriate environment and development is the default. The choice of environment is based on your Babel environment first and if that value is not set, your NPM environment, which should actually be the same, but this makes it more robust.

In general, Release is production and Debug is development.

Experimental feature

One thing that we've noticed is that metro overwrites the test environment variable even if you specify a config so we've added a way to fix this. Make sure to specify the config value as indicated in the wiki and make custom configs for alternative builds. However, if you still need this, such as for a staging / test environment, you can add the APP_ENV environment variable in the CLI. For example:

// package.json
{
  "scripts": {
    "start:staging": "APP_ENV=staging npx react-native start",
  }
}

The above example would use the .env.staging file. The standard word is test, but go nuts.

TypeScript

• Create a types folder in your project
• Inside that folder, create a *.d.tsfile, say, env.d.ts
• in that file, declare a module as the following format:

declare module '@env' {
  export const API_BASE: string;
}

Add all of your .env variables inside this module.

• Finally, add this folder into the typeRoots field in your tsconfig.json file:

{
...
    "typeRoots": ["./src/types"],
...
}

Reference Material

• babel environments
• dotenv documentation
• See the wiki for more troubleshooting tips

Caveats

When using with babel-loader with caching enabled you will run into issues where environment changes won’t be picked up. This is due to the fact that babel-loader computes a cacheIdentifier that does not take your environment into account.

You can easily clear the cache:

rm -rf node_modules/.cache/babel-loader/*

or

yarn start --reset-cache

or

expo r -c

Maybe a solution for updating package.json scripts:

"cc": "rimraf node_modules/.cache/babel-loader/*,",
"android": "npm run cc && react-native run-android",
"ios": "npm run cc && react-native run-ios",

Or you can override the default cacheIdentifier to include some of your environment variables.

The tests that use require('@env') are also not passing.

Credits

• Based on David Chang’s works on babel-plugin-dotenv.
• Also based on Bertrand Marron's works on babel-plugin-dotenv-import.

If you'd like to become an active contributor, please send us a message.

Miscellaneous

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