Docker, containers and images. Why? My main reson is that I do not want to conterminate my main system with all kinds of modules. Or even worse, make it unusable. At the time Centos 7 had python 2.7 but some of software I was running moved to a newer version of python 3.x. Upgrading Centos to a version 3 of python would break te server. When looking at alternatives, I could run a vm or get docker with containers. For a while I ran vm’s, but the overhead was substantial, so I started looking for alternatives and I enden up with docker and still running strong.