Building Docker Images

Docker images consist of applications with their dependencies and they are ready to be launched at scale. In addition, they are suitable to run on cloud servers and data centers because of their lightweight architecture. Docker images are created from the steps defined in Dockerfile, where each instruction forms a layer on top of the previous one. This layered design of images is the prominent feature that makes Docker images lightweight and quick to start. The underlying technology of layered Docker images is the union file system (UFS). The UFS can be considered as stackable layers of files and directories. Each layer is traceable back to its parent layer in a tree structure so that different branches can share the same root. In other words, if two container images have the same base image of ubuntu:18.10, this base image will not be replicated twice; Docker Engine will reuse the same base image to run these two containers. In the next sections, we will present...