Docker and Docker-Compose concepts are two means in Linux by which a developer can easily generate a running container application from a docker image that is pulled down from a repository at GitHub, LinuxServer.io, or DockerHub, then access that running application in a Web browser at a particular port that is assigned to or configured for the application itself. This assignment is performed within a file called the docker-compose.yml file for docker-compose applications. The docker-compose.yml is short for docker-compose YAML file.

The concept of docker containerization in Linux is very similar to the concept of virtualization. Using virtualization in Linux is accomplished through the use of a hypervisor, such as VMWare, Virtual Box, or Virtual Machine Manager. Virtualization allows one to run small Virtual Machines (VMs) on one server platform and they each exhibit the functionality and performance of physical servers, yet are virtual. Containers are not actual servers; that is to say, not in the same way one would typically think of servers.

By increasing portability and using fewer system resources than traditional virtual4 machines, containers make application deployment easier. They are used by DevOps engineers to create workflows that are tailored to agile methodologies, which encourage frequent and incremental code changes.docker versus kubernetes