Docker

Containers

At a high level, containers are a lightweight form of virtual machines which encapsulate an application and its dependencies. However, there are some key differences between containers and virtual machines:

• Some resources are shared with the host operating system, which reduces the overhead involved in comparison with a VM. How much overhead is debatable, especially given that hardware support for virtualisation exists on most modern CPUs, and any machine operating a server is likely to have this available and enabled.
• Portability of containers should make them easier to deploy and migrate across hardware.
• Lower resource utilisation, particularly RAM and CPU, means running a dozen containers is more realistic than the same number of VMs, especially on a developer's laptop.
• Due to the sharing of resources, containers always run the same kernel as the host.