How to Use dotenv-local to Load Environment Variables for Applications and Environments

dotenv-local is a utility library designed to load environment variables with a specific priority order, ideal for managing configurations across different environments like development, production, or testing. In this tutorial, we will show you how to use dotenv-local to load environment variables for different applications and environments.

Installation

To get started, install the library via npm or yarn:

npm install dotenv-local
# or
yarn add dotenv-local

Usage

For a detailed explanation of the available options, refer to the official repository documentation.

Import the Library

Import loadEnv from dotenv-local:

import { loadEnv } from "dotenv-local";

Example for MongoDB Variables

Let's say you have multiple .env files:

• .env: Contains generic environment variables.
• .env.local: Contains local development overrides.
• .env.production: Contains production-specific variables.
• .env.production.local: Contains production overrides.

Using dotenv-local, you can ensure that environment variables related to MongoDB are loaded correctly, with the proper overrides depending on your environment.

Basic Usage

Here is a simple example to load all environment variables, without specific prefixes or options:

import { loadEnv } from "dotenv-local";
const envVariables = loadEnv();
console.log(envVariables);

This will load all the environment variables available in the .env files.

Custom Options for MongoDB

Now, let’s load only MongoDB-related environment variables, with custom options:

import { loadEnv } from "dotenv-local";

const { MONGO_URI, MONGO_PASSWORD } = loadEnv({
  envPrefix: "MONGO_",
  envInitial: {
    MONGO_URI: "mongodb://localhost:27017",
    MONGO_PASSWORD: "mongodb://localhost:27017",
  },
  removeEnvPrefix: false,
});
console.log({ MONGO_URI, MONGO_PASSWORD });

This will load only the environment variables that start with MONGO_, and it will not remove the prefix.

Custom Options for Express

Next, let’s load only environment variables related to Express, using a different prefix:

import { loadEnv } from "dotenv-local";

const { HOST, PORT } = loadEnv({
  envPrefix: "DEPLOY_",
  envInitial: {
    DEPLOY_HOST: "127.0.0.1",
    DEPLOY_PORT: "3000",
  },
  removeEnvPrefix: true,
});
console.log({ HOST, PORT });

This will load the variables DEPLOY_HOST and DEPLOY_PORT from your environment files, removing the DEPLOY_ prefix.

Load Multiple Variables for MongoDB and Express

Now, let’s load environment variables related to both MongoDB and Express using different prefixes:

import { loadEnv } from "dotenv-local";

const { MONGO_URI, MONGO_PASSWORD, DEPLOY_HOST, DEPLOY_PORT } = loadEnv({
  envPrefix: ["DEPLOY_", "MONGO_"],
  envInitial: {
    MONGO_URI: "mongodb://localhost:27017",
    MONGO_PASSWORD: "mongodb://localhost:27017",
    DEPLOY_HOST: "127.0.0.1",
    DEPLOY_PORT: "3000",
  },
  removeEnvPrefix: false,
});
console.log({ MONGO_URI, MONGO_PASSWORD, DEPLOY_HOST, DEPLOY_PORT });

This will load the variables DEPLOY_HOST and DEPLOY_PORT from your environment files, as well as MONGO_URI and MONGO_PASSWORD, without removing their prefixes.

Conclusion

Using dotenv-local, you can easily manage environment variables for different applications and environments (e.g., development, production). By defining custom prefixes, initial values, and the loading order, you can ensure that only the relevant variables for MongoDB, Express, or any other service are loaded, making your configuration process clean and efficient.

For more details on available options and how to configure them, check the official documentation.

License

This project is licensed under the MIT License - see the LICENSE file for details.