Kubernetes ConfigMaps are essential API objects designed to manage application runtime settings by decoupling configuration data from container images, thus enhancing system portability and ease of reconfiguration. ConfigMaps store key-value pairs that can be injected into pods through environment variables, command line arguments, or mounted volume files, allowing for seamless deployment across various environments such as development, testing, and production. While ConfigMaps simplify configuration management, they are limited by their inability to handle sensitive data, which should be managed using Kubernetes Secrets, and they also have a maximum size of 1 MiB. ConfigMaps can be mutable or immutable, with the latter preventing changes post-deployment to improve safety and performance. Tools like Earthly complement ConfigMaps by providing a maintainable build-time configuration approach, facilitating robust and reproducible builds.