What is Docker ?

Docker is a platform that allows developers to package applications into standardized units called containers. It is useful for local testing or for deployment on cloud platforms. The architecture of Docker Docker is a set of tools to create containerized applications. In Docker, we create an image, which is a stack of layers in the form of compressed .tar.gz folders. Each layer contains a "filesystem snapshot" of Linux, along with whiteouts—which act as "death notices" for deleted files. OverlayFS is responsible for "mounting" the image. It traverses each layer from the most recent to the oldest, adding the elements it finds. However, if a specific element already exists in a higher layer or is marked as a whiteout, it is ignored. This process results in a "phantom" or unified view, which serves as the final mounted system. If I run an alpine/jre image on my Ubuntu machine, a process is created that "believes" it is running on an Alpine system with a JRE (thanks to this filesystem "ph