Скачать или смотреть How to Export Async Dependent Constants in a Next.js App Using TypeScript

Learn how to manage environment variables in a TypeScript Next.js app, fetching values from AWS Parameter Store asynchronously.
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Effectively Managing Environment Variables in Next.js with Async Responses

In today's world of web development, managing environment variables securely and efficiently is paramount. Especially in a Next.js application, developers often face challenges when certain constants rely on asynchronous responses—such as fetching secrets from AWS Parameter Store. This post will guide you through a clean solution to this problem, ensuring that your configuration is robust and safe from tampering.

The Challenge

When developing a TypeScript application with Next.js, it's common to juggle multiple environments such as local, staging, and production. Each of these environments may require different settings or secrets. In particular, many developers encounter a scenario where constants like database connection strings must either come from environment variables (process.env) or from AWS Parameter Store. Here’s a typical attempt at achieving this:

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This approach inadvertently leads to type issues, as the PGHOST variable may end up being a promise rather than the intended string. Furthermore, declaring these variables in a mutable manner contradicts the desire for immutability as a security measure. Thankfully, there is a way to resolve these issues while retaining the integrity of your constants.

The Solution

Upgrading to Next.js 12.0.10+

With the introduction of Next.js 12.0.10, async operations within configuration files are supported, allowing for more dynamic environment variable management. Here are the steps you need to follow to craft a solution that checks for variables asynchronously while maintaining a clean codebase:

Rename Configuration File: Start by renaming your next.config.js to next.config.mjs. This allows the file to support ES modules, which is critical for using import statements asynchronously.

Write an Async Function: Create an asynchronous function to fetch the required environment variables from AWS Parameter Store.

Update Your Configuration: Modify the default export of your configuration to include the fetched values along with existing environment variables.

Sample Code Implementation

Here’s a sample implementation demonstrating these steps:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

Imports: The example starts with importing getAsyncSecret from an external package, which handles fetching the secret from AWS.

Async Function: getMyAsyncVariables fetches the asynchronous secret and falls back to process.env or a default value.

Exporting the Configuration: Finally, the configuration is exported asynchronously. This ensures that your environment variables are fully resolved at build time, making them available safely during the application runtime.

Conclusion

With this approach, your Next.js application can safely and efficiently manage environment variables derived from both local settings and remote sources like AWS Parameter Store. By embracing asynchronous functionality in your configurations, you enhance your app's security and flexibility while keeping your constants unchanged throughout the application lifecycle.

By following the steps outlined above, you can ensure your app is ready to handle various environments seamlessly, proving that managing configurations doesn't have to be a daunting task.