Kotlin Environment Variables

Understanding Environment Variables in Kotlin

Environment variables are key-value pairs that are used to configure applications without hardcoding these values into the application code. They are commonly used in applications to store sensitive information like API keys, database credentials, and other configuration parameters that might change between environments (development, testing, production).

In Kotlin, environment variables can be accessed using the System.getenv function. This function retrieves the value of the specified environment variable by name.

Accessing Environment Variables with System.getenv

To access an environment variable in Kotlin, you can use the System.getenv function. This function is part of the Java standard library and thus is readily available in Kotlin.

Here is a simple example of how you can retrieve an environment variable:

Setting Environment Variables

Environment variables are typically set outside the application, often by the operating system or a service like Docker. However, for local development or testing purposes, you can set environment variables in your terminal session before running your Kotlin application.

For example, in a Unix-based system, you can set an environment variable using the export command:

On Windows, you can set an environment variable using the set command:

Handling Missing Environment Variables

It's good practice to handle scenarios where environment variables are not set. You can provide default values or throw an informative error to ensure your application behaves predictably.

Here's an example of providing a default value:

Alternatively, you can throw an exception if a critical environment variable is missing:

Conclusion

Understanding and using environment variables in Kotlin is crucial for developing flexible and secure applications. By leveraging the System.getenv function, you can easily access configuration values that can vary between different deployment environments. Remember to handle the cases where environment variables might not be set to ensure your application remains robust and reliable.