Configuration Validation with Joi

Imagine a scenario in our virtual library where incorrect or missing environment variables have led to application downtime. The database credentials are missing, causing the application to fail to connect to the database, making the virtual library inaccessible to its users. Such an issue emphasizes the importance of validating our environment variables to ensure they meet the expected criteria and formats. This section will use Joi, a powerful validation library, to address and prevent configuration-related issues. Joi allows us to define schemas to validate the structure and contents of our environment variables, ensuring that our application runs with the correct configurations.