How to configure Next.js environmental variables

The article provides an in-depth exploration of managing environment variables in Next.js, highlighting the distinction between public and private variables and emphasizing the importance of securely configuring these variables for both development and production environments. It explains the hierarchy and runtime limitations of environment variable files, noting that Next.js uses multiple .env files, such as .env.local, .env.development, and .env.production, to organize variables according to the environment. Public variables, which are prefixed with NEXT_PUBLIC_, are included in the client-side bundle, while private variables remain server-only. The article stresses best practices, such as using .env.local for secrets and ensuring variables are validated at startup to prevent misconfigurations. It also suggests using environment variables to separate code from configuration to enable a single codebase to function across various environments without modification. The piece concludes with guidance on avoiding the hardcoding of environment-specific logic and highlights the utility of tools like LogRocket for monitoring and debugging Next.js applications.