Externalized configuration

An application usually uses one or many infrastructures third-party services such as a service registry, message broker, server, cloud deployment platform, and so on. Any service must be able to run in multiple environments without any modifications. It should have the ability to pick up external configurations. This pattern is more of a guideline that advises us to externalize all the configurations, including database information, environment info, network location, and so on, that create a startup service that reads this information and prepares the application accordingly. There are various options available. Node.js provides setting environment variables; if you use Docker, then it has the docker-compose.yml file.