Virtual Machines versus Containers

A virtual machine (VM), as the name implies, aims to emulate a physical computer system. Technically, VMs are provisioned by a hypervisor, and the hypervisor runs on the host OS. The following diagram illustrates this concept:

Figure 1.1: Running applications on VMs

Here, the VMs have full OS stacks, and the OS running on the VM (called the Guest OS) must rely on the underlying hypervisor to function. The applications and operating system reside and run inside the VM. Their operations go through the guest OS's kernel and are then translated to the system calls by the hypervisor, which are eventually executed on the host OS.

Containers, on the other hand, don't need a hypervisor underneath. By leveraging some Linux containerization technologies such as namespaces and cgroups (which we will revisit later), each container runs independently on the host OS. The following diagram illustrates containerization, taking...