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“Docker is one of the most popular virtualization approaches that uses Linux containers rather than virtual machines as a way of isolating application data and computing on shared resources.”

Fair Use Source:


Docker is an open-source project that automates the deployment of Linux applications inside software containers. Quote of features from Docker web pages:

Docker provides an additional layer of abstraction and automation of operating-system-level virtualization on Linux.<ref name=“SYS-CON Media”>

</ref> Docker uses the resource isolation features of the Linux kernel such as cgroups and kernel namespaces, and a union-capable file system such as OverlayFS and others<ref>

</ref> to allow independent “containers” to run within a single Linux instance, avoiding the overhead of starting and maintaining virtual machines.<ref>


The Linux kernel's support for namespaces mostly<ref>

</ref> isolates an application's view of the operating environment, including process trees, network, user IDs and mounted file systems, while the kernel's cgroups provide resource limiting, including the CPU, memory, block I/O and network. Since version 0.9, Docker includes the

library as its own way to directly use virtualization facilities provided by the Linux kernel, in addition to using abstracted virtualization interfaces via libvirt, LXC (Linux Containers) and systemd-nspawn.<ref name=“zdnet-7000030397”>


</ref><ref name=“docker-blog-201403”>




As actions are done to a Docker base image, union file system layers are created and documented, such that each layer fully describes how to recreate an action. This strategy enables Docker's lightweight images, as only layer updates need to be propagated (compared to full VMs, for example).

According to industry analyst firm 451 Research, “Docker is a tool that can package an application and its dependencies in a virtual container that can run on any Linux server. This helps enable flexibility and portability on where the application can run, whether on premises, public cloud, private cloud, bare metal, etc.”<ref name=“Linux”>


Docker implements a high-level API to provide lightweight containers that run processes in isolation.<ref name=“infoq-201303”>


Building on top of facilities provided by the Linux kernel (primarily cgroups and namespaces), a Docker container, unlike a virtual machine, does not require or include a separate operating system.<ref name=“Linux” /> Instead, it relies on the kernel's functionality and uses resource isolation (CPU, memory, block I/O, network, etc.) and separate namespaces to isolate the application's view of the operating system. Docker accesses the Linux kernel's virtualization features either directly using the

library, which is available as of Docker&nbsp;0.9, or indirectly via


(Linux Containers) or

.<ref name=“docker-blog-201403” /><ref name=“infoq-201403”>


Because Docker containers are so lightweight, a single server or virtual machine can run several containers simultaneously. A 2016 analysis found that a typical Docker use case involves running five containers per host, but that many organizations run 10 or more.<ref>


By using containers, resources can be isolated, services restricted, and processes provisioned to have an almost completely private view of the operating system with their own process ID space, file system structure, and network interfaces. Multiple containers share the same kernel, but each container can be constrained to only use a defined amount of resources such as CPU, memory and I/O.

Using Docker to create and manage containers may simplify the creation of highly distributed systems by allowing multiple applications, worker tasks and other processes to run autonomously on a single physical machine or across multiple virtual machines. This allows the deployment of nodes to be performed as the resources become available or when more nodes are needed, allowing a platform as a service (PaaS)-style of deployment and scaling for systems like Apache Cassandra, MongoDB or Riak. Docker also simplifies the creation and operation of task or workload queues and other distributed systems.<ref name=“CloudAve”>

</ref><ref name=“”>



Docker can be integrated into various infrastructure tools, including Amazon Web Services,<ref>

</ref> Ansible,<ref>

</ref> CFEngine,<ref>

</ref> Chef,<ref>

</ref> Google Cloud Platform,<ref>

</ref> IBM Bluemix,<ref>

</ref> Jelastic,<ref>

</ref> Jenkins,<ref>

</ref> Microsoft Azure,<ref>

</ref> OpenStack Nova,<ref>

</ref> OpenSVC,<ref>

</ref> HPE Helion Stackato, Puppet,<ref>

</ref> Salt,<ref>

</ref> Vagrant,<ref>

</ref> and VMware vSphere Integrated Containers.<ref> VMware vSphere Integrated Containers (VIC)</ref><ref> VMware’s Photon Platform and How it Treats Containers</ref>

The Cloud Foundry Diego project integrates Docker into the Cloud Foundry PaaS.<ref>


Red Hat's OpenShift PaaS integrates Docker and related project (Kubernetes, Geard, Project Atomic and others) since v3 (June 2015).<ref>


The Apprenda PaaS integrates Docker containers in version 6.0 of its product.<ref>



Solomon Hykes started Docker in France as an internal project within dotCloud, a platform-as-a-service company,<ref>

</ref> with initial contributions by other dotCloud engineers including Andrea Luzzardi and Francois-Xavier Bourlet.

Jeff Lindsay also became involved as an independent collaborator.

Docker represents an evolution of dotCloud's proprietary technology, which is itself built on earlier open-source projects such as Cloudlets.

Docker was released as open source in March 2013.<ref name=“infoq-201303” /> On March 13, 2014, with the release of version 0.9, Docker dropped LXC as the default execution environment and replaced it with its own

library written in the Go programming language.<ref name=“zdnet-7000030397” /><ref name=“infoq-201403” />

, the project had over 25,600 GitHub stars (making it the 20th most-starred GitHub project), over 6,800 forks, and nearly 1,100 contributors.<ref name=“GitHub”>


A May 2016 analysis showed the following organizations as main contributors to Docker: The Docker team, Cisco, Google, Huawei, IBM, Microsoft, and Red Hat.<ref>



  • On September 19, 2013, Red Hat and Docker announced a significant collaboration around Fedora, Red Hat Enterprise Linux, and OpenShift.<ref>


  • On October 15, 2014, Microsoft announced integration of the Docker engine into the next (2016) Windows Server release, and native support for the Docker client role in Windows.<ref>



  • On December 4, 2014, IBM announced a strategic partnership with Docker that enables enterprises to more efficiently, quickly and cost-effectively build and run the next generation of applications in the IBM Cloud.<ref>


  • On June 22, 2015, Docker and several other companies announced that they are working on a new vendor and operating-system-independent standard for software containers.<ref>



  • On June 8, 2016, Microsoft announced that Docker now could be used natively on Windows 10 with Hyper-V Containers, to build, ship and run containers utilizing the Windows Server 2016 Technical Preview 5 Nano Server container OS image.<ref>


  • On October 4, 2016, Solomon Hykes announced InfraKit as a new self-healing container infrastructure effort for Docker container environments.<ref>



See also



External sites

docker.txt · Last modified: 2016/12/10 16:26 by Cloud Monk Losang Jinpa PhD MCSE MCT Microsoft Cloud Ecosystem DevOps Engineer