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Moby Project - a collaborative project for the container ecosystem to assemble container-based systems
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Solomon Hykes 2af030ab57 beam/data: Message.GetOne() returns the last value set at a key
This is a convenience for callers which are only interested in one value
per key. Similar to how HTTP headers allow multiple keys per value, but
are often used to store and retrieve only one value.

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
2014-05-09 17:01:27 -07:00
api rename goruntime import to runtime 2014-05-09 10:14:37 +03:00
archive Change owner only on copied content 2014-05-07 20:40:22 +04:00
builtins remove fixme 2014-05-03 00:54:52 +00:00
contrib mkimage-debootstrap: set ubuntuLatestLTS as Trusty 2014-05-07 08:26:24 +01:00
daemon devmapper: Remove accidental debug spew 2014-05-08 19:25:47 +02:00
daemonconfig This patch reworks the SELinux patch to be only run on demand by the daemon 2014-04-29 03:40:05 -07:00
docker improve some usages 2014-05-06 21:32:12 +00:00
dockerinit Move even more stuff into dockerversion 2014-02-11 17:26:54 -07:00
dockerversion Move even more stuff into dockerversion 2014-02-11 17:26:54 -07:00
docs Added value format description for VOLUME instruction 2014-05-09 16:37:55 +02:00
engine Engine: ensure all pipes are properly closed by Receiver and Sender 2014-05-09 16:12:21 -07:00
graph Initial work on selinux patch 2014-04-29 03:40:05 -07:00
hack Merge pull request #5463 from tianon/hack-dind-cgroup 2014-05-09 13:54:52 -07:00
image Initial work on selinux patch 2014-04-29 03:40:05 -07:00
integration rename goruntime import to runtime 2014-05-09 10:14:37 +03:00
integration-cli Change owner only on copied content 2014-05-07 20:40:22 +04:00
links Extract our default PATH value to a constant for great reuse 2014-02-22 20:01:45 -07:00
nat nat: Fix --expose protocol parsing 2014-05-05 12:54:10 +02:00
opts env-file: variable behavior 2014-03-31 14:45:13 -04:00
pkg beam/data: Message.GetOne() returns the last value set at a key 2014-05-09 17:01:27 -07:00
registry Merge pull request #5600 from unclejack/sha512_registry_support 2014-05-05 15:27:11 -07:00
runconfig returns an error when using -h and --net 2014-05-09 21:42:22 +00:00
server rename goruntime import to runtime 2014-05-09 10:14:37 +03:00
sysinit Rename runtime/* to daemon/* 2014-04-17 14:43:01 -07:00
utils add resolvconf 2014-05-05 22:55:32 +00:00
vendor Update vendored deps that have a proper version number to use said specific versions 2014-05-03 20:34:21 -06:00
.gitignore Docs: Add docs new version files created by make docs to .gitignore 2014-04-24 13:33:00 +03:00
.mailmap Update .mailmap and AUTHORS 2014-02-04 13:40:56 -07:00
.travis.yml remove the sphinx validation - we'll add a MarkDown one when we have it 2014-04-29 13:43:13 +10:00
AUTHORS Merge pull request #5400 from bmatsuo/5398-fix-pkg/graphdb-osx 2014-05-05 13:41:43 -07:00
CHANGELOG.md Bump to version v0.11.1 2014-05-07 17:29:56 -07:00
CONTRIBUTING.md Post-commit hook URL fix 2014-05-05 10:28:52 -04:00
Dockerfile Revert "add apparmor to the Dockerfile" 2014-05-01 21:49:53 +00:00
FIXME Update fixme 2014-02-14 15:17:12 -08:00
LICENSE Fix boilerplate text in Apache license 2014-03-12 23:39:36 -07:00
MAINTAINERS Clean up MAINTAINERS files 2014-04-21 18:17:13 -07:00
Makefile Add new test-unit make rule which only runs the unit tests. Renames test 2014-04-29 23:26:27 +00:00
NOTICE Fixes 3497 2014-01-13 17:12:53 -08:00
README.md Fix logo in README.md 2014-05-06 11:39:11 -07:00
VERSION Change version to v0.11.1-dev 2014-05-07 18:48:38 -07:00

Docker: the Linux container engine

Docker is an open source project to pack, ship and run any application as a lightweight container

Docker containers are both hardware-agnostic and platform-agnostic. This means that they can run anywhere, from your laptop to the largest EC2 compute instance and everything in between - and they don't require that you use a particular language, framework or packaging system. That makes them great building blocks for deploying and scaling web apps, databases and backend services without depending on a particular stack or provider.

Docker is an open-source implementation of the deployment engine which powers dotCloud, a popular Platform-as-a-Service. It benefits directly from the experience accumulated over several years of large-scale operation and support of hundreds of thousands of applications and databases.

Docker L

Better than VMs

A common method for distributing applications and sandboxing their execution is to use virtual machines, or VMs. Typical VM formats are VMWare's vmdk, Oracle Virtualbox's vdi, and Amazon EC2's ami. In theory these formats should allow every developer to automatically package their application into a "machine" for easy distribution and deployment. In practice, that almost never happens, for a few reasons:

  • Size: VMs are very large which makes them impractical to store and transfer.
  • Performance: running VMs consumes significant CPU and memory, which makes them impractical in many scenarios, for example local development of multi-tier applications, and large-scale deployment of cpu and memory-intensive applications on large numbers of machines.
  • Portability: competing VM environments don't play well with each other. Although conversion tools do exist, they are limited and add even more overhead.
  • Hardware-centric: VMs were designed with machine operators in mind, not software developers. As a result, they offer very limited tooling for what developers need most: building, testing and running their software. For example, VMs offer no facilities for application versioning, monitoring, configuration, logging or service discovery.

By contrast, Docker relies on a different sandboxing method known as containerization. Unlike traditional virtualization, containerization takes place at the kernel level. Most modern operating system kernels now support the primitives necessary for containerization, including Linux with openvz, vserver and more recently lxc, Solaris with zones and FreeBSD with Jails.

Docker builds on top of these low-level primitives to offer developers a portable format and runtime environment that solves all 4 problems. Docker containers are small (and their transfer can be optimized with layers), they have basically zero memory and cpu overhead, they are completely portable and are designed from the ground up with an application-centric design.

The best part: because Docker operates at the OS level, it can still be run inside a VM!

Plays well with others

Docker does not require that you buy into a particular programming language, framework, packaging system or configuration language.

Is your application a Unix process? Does it use files, tcp connections, environment variables, standard Unix streams and command-line arguments as inputs and outputs? Then Docker can run it.

Can your application's build be expressed as a sequence of such commands? Then Docker can build it.

Escape dependency hell

A common problem for developers is the difficulty of managing all their application's dependencies in a simple and automated way.

This is usually difficult for several reasons:

  • Cross-platform dependencies. Modern applications often depend on a combination of system libraries and binaries, language-specific packages, framework-specific modules, internal components developed for another project, etc. These dependencies live in different "worlds" and require different tools - these tools typically don't work well with each other, requiring awkward custom integrations.

  • Conflicting dependencies. Different applications may depend on different versions of the same dependency. Packaging tools handle these situations with various degrees of ease - but they all handle them in different and incompatible ways, which again forces the developer to do extra work.

  • Custom dependencies. A developer may need to prepare a custom version of their application's dependency. Some packaging systems can handle custom versions of a dependency, others can't - and all of them handle it differently.

Docker solves dependency hell by giving the developer a simple way to express all their application's dependencies in one place, and streamline the process of assembling them. If this makes you think of XKCD 927, don't worry. Docker doesn't replace your favorite packaging systems. It simply orchestrates their use in a simple and repeatable way. How does it do that? With layers.

Docker defines a build as running a sequence of Unix commands, one after the other, in the same container. Build commands modify the contents of the container (usually by installing new files on the filesystem), the next command modifies it some more, etc. Since each build command inherits the result of the previous commands, the order in which the commands are executed expresses dependencies.

Here's a typical Docker build process:

FROM ubuntu:12.04
RUN apt-get update
RUN apt-get install -q -y python python-pip curl
RUN curl -L https://github.com/shykes/helloflask/archive/master.tar.gz | tar -xzv
RUN cd helloflask-master && pip install -r requirements.txt

Note that Docker doesn't care how dependencies are built - as long as they can be built by running a Unix command in a container.

Getting started

Docker can be installed on your local machine as well as servers - both bare metal and virtualized. It is available as a binary on most modern Linux systems, or as a VM on Windows, Mac and other systems.

We also offer an interactive tutorial for quickly learning the basics of using Docker.

For up-to-date install instructions and online tutorials, see the Getting Started page.

Usage examples

Docker can be used to run short-lived commands, long-running daemons (app servers, databases etc.), interactive shell sessions, etc.

You can find a list of real-world examples in the documentation.

Under the hood

Under the hood, Docker is built on the following components:

Contributing to Docker

Want to hack on Docker? Awesome! There are instructions to get you started here.

They are probably not perfect, please let us know if anything feels wrong or incomplete.

Brought to you courtesy of our legal counsel. For more context, please see the Notice document.

Use and transfer of Docker may be subject to certain restrictions by the United States and other governments.
It is your responsibility to ensure that your use and/or transfer does not violate applicable laws.

For more information, please see http://www.bis.doc.gov