Puppet and Docker

With the popularization of containerization technologies, new ways of approaching services provisioning have started to become popular; these technologies are based in the features of operating systems to start processes on the same kernel, but with isolated resources.

If we compare with virtualization technologies, virtual machines are generally started as full operating systems that have access to an emulated hardware stack, this emulated stack introduces some performance penalties, as some translations are needed so the operations in the virtual machine can reach the physical hardware. These penalties do not exist in containerization, because containers are directly executed on the host kernel and over the physical hardware. Isolation in containers happens at the level of operating system resources.

Before talking about the implications containers have for systems provisioning, let's see some examples of the isolation technologies the Linux kernel offers to containers...