When Docker burst onto the scene in 2013, Linux containers seemed like an overnight success. But the evolution to containers—and microservices and Kubernetes—was actually decades in the making, based on kernel primitives in the Linux operating system. Docker used these primitives, namely cgroups and namespaces, as building blocks to create a lightweight, easy-to-use software packaging format. Linux containers had been used by Google and others for many years, but Docker made them easily accessible to mainstream developers.
