Docker is a set of platform as a service (PaaS) products that use OS-level virtualization to deliver software in packages called containers. Containers are isolated from one another and bundle their own software, libraries and configuration files; they can communicate with each other through well-defined channels. All containers are run by a single operating-system kernel and are thus more lightweight than virtual machines.
|Original author(s)||Solomon Hykes|
|Initial release||March 20, 2013|
19.03.5 / November 13, 2019
|Operating system||Linux, Windows, macOS[a]|
|Platform||x86-64, ARM, s390x, ppc64le|
Docker, inc. was founded by Solomon Hykes and Sebastien Pahl during the Y Combinator Summer 2010 startup incubator group and launched in 2011. Hykes started the Docker project in France as an internal project within dotCloud, a platform-as-a-service company.
Docker debuted to the public in Santa Clara at PyCon in 2013. It was released as open-source in March 2013. At the time, it used LXC as its default execution environment. One year later, with the release of version 0.9, Docker replaced LXC with its own component, which was written in the Go programming language.
- On September 19, 2013, Red Hat and Docker announced a collaboration around Fedora, Red Hat Enterprise Linux (RHEL), and OpenShift.
- On October 15, 2014, Microsoft announced the integration of the Docker engine into Windows Server, as well as native support for the Docker client role in Windows.
- In November 2014 Docker container services were announced for the Amazon Elastic Compute Cloud (EC2).
- On November 10, 2014, Docker announced a partnership with Stratoscale.
- On December 4, 2014, IBM announced a strategic partnership with Docker that enables Docker to integrate more closely with the IBM Cloud.
- 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.
- In April 2016, Windocks, an independent ISV released a port of Docker's open source project to Windows, supporting Windows Server 2012 R2 and Server 2016, with all editions of SQL Server 2008 onward.
- A May 2016 analysis showed the following organizations as main contributors to Docker: The Docker team, Cisco, Google, Huawei, IBM, Microsoft, and Red Hat.
- On June 8, 2016, Microsoft announced that Docker now could be used natively on Windows 10.
- A January 2017 analysis of LinkedIn profile mentions showed Docker presence grew by 160% in 2016.
- On May 6, 2019, Microsoft announced the second version of Windows Subsystem for Linux (WSL). Docker, Inc. announced that it has started working on a version of Docker for Windows that runs on WSL 2.
Docker can package an application and its dependencies in a virtual container that can run on any Linux server. This helps provide flexibility and portability enabling the application to be run in various locations, whether on-premises, in a public cloud, or in a private cloud. 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) to allow containers to run within a single Linux instance, avoiding the overhead of starting and maintaining virtual machines. Because Docker containers are lightweight, a single server or virtual machine can run several containers simultaneously. A 2018 analysis found that a typical Docker use case involves running eight containers per host, but that a quarter of analyzed organizations run 18 or more per host.
The Linux kernel's support for namespaces mostly 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 for memory and CPU. Since version 0.9, Docker includes its own component (called "libcontainer") to directly use virtualization facilities provided by the Linux kernel, in addition to using abstracted virtualization interfaces via libvirt, LXC and systemd-nspawn.
The Docker software as a service offering consists of three components:
- Software: The Docker daemon, called
dockerd, is a persistent process that manages Docker containers and handles container objects. The daemon listens for requests sent via the Docker Engine API. The Docker client program, called
docker, provides a command-line interface that allows users to interact with Docker daemons.
- Objects: Docker objects are various entities used to assemble an application in Docker. The main classes of Docker objects are images, containers, and services.
- A Docker container is a standardized, encapsulated environment that runs applications. A container is managed using the Docker API or CLI.
- A Docker image is a read-only template used to build containers. Images are used to store and ship applications.
- A Docker service allows containers to be scaled across multiple Docker daemons. The result is known as a swarm, a set of cooperating daemons that communicate through the Docker API.
- Registries: A Docker registry is a repository for Docker images. Docker clients connect to registries to download ("pull") images for use or upload ("push") images that they have built. Registries can be public or private. Two main public registries are Docker Hub and Docker Cloud. Docker Hub is the default registry where Docker looks for images. Docker registries also allow the creation of notifications based on events.
- Docker Compose is a tool for defining and running multi-container Docker applications. It uses YAML files to configure the application's services and performs the creation and start-up process of all the containers with a single command. The
docker-composeCLI utility allows users to run commands on multiple containers at once, for example, building images, scaling containers, running containers that were stopped, and more. Commands related to image manipulation, or user-interactive options, are not relevant in Docker Compose because they address one container. The docker-compose.yml file is used to define an application's services and includes various configuration options. For example, the
buildoption defines configuration options such as the Dockerfile path, the
commandoption allows one to override default Docker commands, and more. The first public beta version of Docker Compose (version 0.0.1) was released on December 21, 2013. The first production-ready version (1.0) was made available on October 16, 2014.
- Docker Swarm provides native clustering functionality for Docker containers, which turns a group of Docker engines into a single virtual Docker engine. In Docker 1.12 and higher, Swarm mode is integrated with Docker Engine. The
docker swarmCLI utility allows users to run Swarm containers, create discovery tokens, list nodes in the cluster, and more. The
docker nodeCLI utility allows users to run various commands to manage nodes in a swarm, for example, listing the nodes in a swarm, updating nodes, and removing nodes from the swarm. Docker manages swarms using the Raft Consensus Algorithm. According to Raft, for an update to be performed, the majority of Swarm nodes need to agree on the update.
- Barbier, Julien (June 9, 2014). "It's Here: Docker 1.0". Docker. Docker, Inc. Retrieved September 30, 2019.
- "Releases - docker/docker-ce". docker/docker-ce repo. Docker, Inc. Retrieved November 16, 2019 – via GitHub.
- "Docker source code". docker/distribution repo. Docker, Inc. October 12, 2015. Retrieved October 24, 2015 – via GitHub.
- "Get started with Docker for Mac". docker.com. Docker, Inc. Retrieved September 27, 2018.
- Friis, Michael (March 2, 2017). "Announcing Docker Enterprise Edition". Docker Blog. Docker, Inc. Retrieved March 2, 2017.
- O'Gara, Maureen (July 26, 2013). "Ben Golub, Who Sold Gluster to Red Hat, Now Running dotCloud". SYS-CON Media. Retrieved August 9, 2013.
- "Docker frequently asked questions (FAQ)". March 2, 2019.
- "What is a Container?". docker.com. Docker, Inc. Retrieved May 13, 2019.
- Ratan, Vivek (February 8, 2017). "Docker: A Favourite in the DevOps World". Open Source For U. Retrieved June 14, 2017.
- "About the dotCloud Platform". dotCloud. Retrieved June 23, 2019.
- "One home for all your apps". dotcloud.com. Archived from the original on May 17, 2014. Retrieved May 8, 2014.
- "The future of Linux Containers". DotCloud Channel. Retrieved July 13, 2018 – via YouTube.
- Avram, Abel (March 27, 2013). "Docker: Automated and Consistent Software Deployments". InfoQ. Retrieved August 9, 2013.
- Vaughan-Nichols, Steven J. (June 11, 2014). "Docker libcontainer unifies Linux container powers". ZDNet. Retrieved July 30, 2014.
- Swan, Chris (March 13, 2014). "Docker drops LXC as default execution environment". InfoQ. Retrieved January 20, 2015.
- "DotCloud Pivots And Wins Big With Docker, The Cloud Service Now Part Of Red Hat OpenShift". TechCrunch. September 19, 2013. Retrieved January 20, 2014.
- Foley, Mary Jo (October 15, 2014). "Docker container support coming to Microsoft's next Windows Server release". ZDNet. Retrieved October 16, 2014.
- Guthrie, Scott (October 15, 2014). "Docker and Microsoft: Integrating Docker with Windows Server and Microsoft Azure". ScottGu's Blog. Microsoft. Retrieved January 12, 2015.
- Barr, Jeff (November 13, 2014). "Amazon EC2 Container Service (ECS) – Container Management for the AWS Cloud". Amazon Web Services Blog. Retrieved April 29, 2017.
- Rath, John (November 10, 2014). "Stratoscale Raises $32M to Build Docker-Supporting OpenStack Clouds on Commodity Servers". Retrieved January 3, 2016.
- "IBM and Docker Announce Strategic Partnership to Deliver Enterprise Applications in the Cloud and On Prem". IBM. December 4, 2014. Retrieved April 20, 2015.
- Lardinois, Frederic (June 22, 2015). "Docker, CoreOS, Google, Microsoft, Amazon And Others Come Together To Develop Common Container Standard". TechCrunch. Retrieved August 8, 2015.
- Siluk, Shirley (June 22, 2015). "Docker, Tech Giants Team on Open Container Project". cio-today.com. Retrieved August 8, 2015.
- Yegulalp, Serdar (April 4, 2016). "Windocks does what Docker and Microsoft can't do". InfoWorld. Retrieved October 27, 2018.
- "Docker – Updated project statistics". GitHub Gist. Retrieved August 22, 2016.
- Sarkar, Dona (June 8, 2016). "Announcing Windows 10 Insider Preview Build 14361". Windows Blogs. Microsoft. Retrieved June 19, 2016.
- Vaughan-Nichols, Steven (June 18, 2019). "Docker embraces Windows Subsystem for Linux 2". ZDNet. CBS Interactive.
- "Docker 0.9: Introducing execution drivers and libcontainer". Docker Blog. Docker, Inc. March 10, 2014. Retrieved January 20, 2015.
- Noyes, Katherine (August 1, 2013). "Docker: A 'Shipping Container' for Linux Code". Linux.com. Retrieved August 9, 2013.
- "Select a storage driver documentation". Docker documentation. Archived from the original on December 6, 2016. Retrieved December 7, 2016.
- "Docker Documentation: Kernel Requirements". docker.readthedocs.org. January 4, 2014. Archived from the original on August 21, 2014. Retrieved August 20, 2014.
- K., Chris (14 January 2019). "Lightweight Windows containers: Using Docker process isolation in Windows 10" (html). Poweruser. Retrieved 2 August 2019.
more “lightweight” real containers (via so called process-isolation), where the containerized processes are running directly on the host system — all processes on the host and in the containers are sharing the same Windows kernel. This is similar to how containers on Linux work.
- "8 surprising facts about real Docker adoption". Datadog. June 2018. Retrieved September 4, 2019.
- Walsh, Dan (September 15, 2014). "Yet Another Reason Containers Don't Contain: Kernel Keyrings". projectatomic.io. Retrieved April 13, 2015.
- "Limit a container's resources". Docker Documentation. Retrieved March 7, 2018.
- "libcontainer – reference implementation for containers". docker/libcontainer repo. Docker, Inc. Retrieved July 30, 2014 – via GitHub].
- "Docker overview". Docker Documentation. Docker, Inc. Retrieved February 26, 2018.
- "dockerd". Docker Documentation. Docker, Inc. Retrieved February 26, 2018.
- "Use the Docker command line". Docker Documentation. Docker, Inc. Retrieved February 26, 2018.
- "The Docker Ecosystem: An Introduction to Common Components". www.digitalocean.com. Retrieved February 26, 2018.
- "About Registry". Docker Documentation. Docker, Inc. Retrieved February 26, 2018.
- "Work with notifications". March 2, 2019.
- "Overview of Docker Compose". Docker Documentation. Docker, Inc. Retrieved July 6, 2017.
- "Compose command-line reference". Docker Documentation. Docker, Inc. Retrieved February 28, 2018.
- "Orchestrate Containers for Development with Docker Compose". via @codeship. May 27, 2015. Retrieved February 28, 2018.
- "Compose file version 3 reference". Docker Documentation. Docker, Inc. Retrieved February 28, 2018.
- Firshman, Ben (December 21, 2013). "Release 0.0.1". docker/compose. Docker, Inc. – via GitHub.
- Prasad, Aanand (October 16, 2014). "Release 1.0.0". docker/compose. Docker, Inc. – via GitHub.
- "8 Container Orchestration Tools to Know". Linux.com. April 12, 2017. Retrieved July 6, 2017.
- "Docker Swarm". Docker Documentation. Docker, Inc. Retrieved July 6, 2017.
- "Swarm command-line reference". Docker Documentation. Docker, Inc. Retrieved February 28, 2018.
- "docker node". Docker Documentation. Retrieved February 28, 2018.
- "Docker Swarm 101". aquasec.com. Retrieved February 28, 2018.
- "Raft Consensus Algorithm". raft.github.io. Retrieved February 28, 2018.