Gatsby.js Environment Variables: A Comprehensive Guide

Environment variables play a crucial role in Gatsby.js applications, enabling developers to configure and manage their projects effectively. They provide a secure and convenient way to store sensitive data, handle configuration options, and control the behavior of Gatsby sites.

What are Environment Variables?

Environment variables are key-value pairs that store configuration information for applications. They are typically defined outside the codebase, either in the operating system environment or through configuration files. Gatsby.js provides a mechanism to access and utilize these variables within your application, allowing for dynamic and customizable behavior.

Types of Environment Variables

There are two main types of environment variables that can be used in Gatsby.js applications:

• Process Environment Variables: These are variables defined in the operating system environment. They can be accessed using the process.env global object.
• Gatsby Environment Variables: These are variables defined specifically for Gatsby.js applications and are accessed through the gatsby.env object.

Configuring Environment Variables

To configure environment variables for your Gatsby.js application, you can use the following methods:

• .env File: Create a .env file in the root of your Gatsby project and specify your environment variables as key-value pairs, one per line.
• Environment Files: Gatsby supports multiple environment files, allowing you to define different sets of variables for different environments (e.g., development, staging, production). Create separate files such as .env.development and .env.production and place them in the root of your project.
• Command-Line Arguments: You can also pass environment variables as command-line arguments when running Gatsby commands. For example: gatsby develop --env.API_URL=https://my-api.com.

Accessing Environment Variables

Once you have configured your environment variables, you can access them within your Gatsby.js application as follows:

• Process Environment Variables: Use the process.env global object. For example: const apiUrl = process.env.API_URL;

Exposing GATSBY_-Prefixed Environment Variables to Client

Gatsby.js also provides a mechanism to expose certain environment variables to the client-side of your application. This is achieved through the use of GATSBY_ prefixed environment variables.

When you define an environment variable with a GATSBY_ prefix, its value becomes available to your Gatsby application's client-side code. This is particularly useful for exposing configuration options or other sensitive data that you need to access in your frontend scripts.

To expose a GATSBY_ prefixed environment variable to the client, simply define it in your .env file or environment file as usual. For example:

GATSBY_API_URL=https://my-api.com

Once defined, you can access the value of this environment variable in your client-side code using the window.gatsby object. For example, to access the GATSBY_API_URL variable in your React component:

import React from "react";

const MyComponent = () => {
  const apiUrl = `${process.env.GATSBY_API_URL}`;

  return (
    <div>
      <h1>API URL: {apiUrl}</h1>
    </div>
  );
};

export default MyComponent;

Security Considerations

It's important to note that exposing environment variables to the client can pose security risks, as they can be accessed by anyone with access to your website's source code. Therefore, it's crucial to only expose variables that are safe to be shared publicly.

Avoid exposing sensitive data such as API keys, database credentials, or any other information that could compromise the security of your application or its users.

Best Practices

• Store sensitive data securely using environment variables, but avoid exposing them to the client.
• Use default values for your environment variables to handle cases where they are not explicitly set.
• Validate input values for environment variables to prevent errors or unexpected behavior.
• Follow naming conventions for your environment variables to improve readability and maintenance.
• Add .env* files to .gitignore to prevent sensitive data from being committed to your source code repository.

Adding .env* Files to .gitignore

To prevent your environment files from being accidentally committed to your source code repository, it's recommended to add them to your .gitignore file. This will ensure that they are excluded from version control, protecting your sensitive data.

To add .env* files to .gitignore, open the file in the root of your Gatsby project and add the following line:

.env*

This will ignore all files that start with .env, including .env, .env.development, .env.production, and any other environment files you may have created.

Conclusion

Environment variables are a powerful tool for enhancing the flexibility and security of your Gatsby.js applications. By understanding the different types, configuration methods, best practices, and security considerations outlined in this blog post, you can effectively manage your project's settings, store sensitive data securely, and create dynamic and customizable Gatsby sites.