Rarely has such a young software raised so much attention in such as short time as the Docker [1] container manager. Docker is one of the fastest growing open source developments in the history of free software. Released in March of 2013, it made it to version 1.0 in June of 2014 and was declared ready for production. In the same month, Docker was already part of Red Hat's release of RHEL 7. Further cooperative agreements exist with Canonical, openSUSE, CoreOS, VMware and others. Along with that, Docker is a member of Google's Kubernetes project [2].

The visualization associated with the name Docker sums it up: a ship/computer is loaded with containers that you can stack, transport, isolate, and protect (Figure 1). Docker containers in IT are isolated virtual environments for isolated execution of processes and applications. Docker is currently used primarily for developing, testing, and deploying applications and can isolate them along with their dependencies in containers. These applications have practically no overhead and can run nearly as fast as native applications.

Unlike the well-known hypervisors [3] VirtualBox, VMware Workstation, HyperV, Parallels Desktop or Xen, a Docker container doesn't need its own operating system. Each container uses the basic functions of its host system and is therefore self-sufficient and isolated from other containers. Only the host's kernel needs to match that of the guest.

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