docker

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README

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

Documentation

Index

Constants

This section is empty.

Variables

View Source 
var (
	ErrDockerfileEmpty = errors.New("Dockerfile cannot be empty")
)

Functions

func GetVersion 

func GetVersion(job *engine.Job) engine.Status

func InitServer 

func InitServer(job *engine.Job) engine.Status

jobInitApi runs the remote api server `srv` as a daemon, Only one api server can run at the same time - this is enforced by a pidfile. The signals SIGINT, SIGQUIT and SIGTERM are intercepted for cleanup.

Types

type BuildFile 

type BuildFile interface {
	Build(io.Reader) (string, error)
	CmdFrom(string) error
	CmdRun(string) error
}

func NewBuildFile 

func NewBuildFile(srv *Server, outStream, errStream io.Writer, verbose, utilizeCache, rm bool, outOld io.Writer, sf *utils.StreamFormatter, auth *auth.AuthConfig, authConfigFile *auth.ConfigFile) BuildFile

type Server 

type Server struct {
	sync.RWMutex

	Eng *engine.Engine
	// contains filtered or unexported fields
}

func NewServer 

func NewServer(eng *engine.Engine, config *daemonconfig.Config) (*Server, error)

func (*Server) AddEvent 

func (srv *Server) AddEvent(jm utils.JSONMessage)

func (*Server) Auth 

func (srv *Server) Auth(job *engine.Job) engine.Status

func (*Server) Build 

func (srv *Server) Build(job *engine.Job) engine.Status

func (*Server) Close 

func (srv *Server) Close() error

func (*Server) ContainerAttach 

func (srv *Server) ContainerAttach(job *engine.Job) engine.Status

func (*Server) ContainerChanges 

func (srv *Server) ContainerChanges(job *engine.Job) engine.Status

func (*Server) ContainerCommit 

func (srv *Server) ContainerCommit(job *engine.Job) engine.Status

func (*Server) ContainerCopy 

func (srv *Server) ContainerCopy(job *engine.Job) engine.Status

func (*Server) ContainerCreate 

func (srv *Server) ContainerCreate(job *engine.Job) engine.Status

func (*Server) ContainerDestroy 

func (srv *Server) ContainerDestroy(job *engine.Job) engine.Status

func (*Server) ContainerExport 

func (srv *Server) ContainerExport(job *engine.Job) engine.Status

func (*Server) ContainerInspect 

func (srv *Server) ContainerInspect(name string) (*runtime.Container, error)

func (*Server) ContainerKill 

func (srv *Server) ContainerKill(job *engine.Job) engine.Status

ContainerKill send signal to the container If no signal is given (sig 0), then Kill with SIGKILL and wait for the container to exit. If a signal is given, then just send it to the container and return.

func (*Server) ContainerResize 

func (srv *Server) ContainerResize(job *engine.Job) engine.Status

func (*Server) ContainerRestart 

func (srv *Server) ContainerRestart(job *engine.Job) engine.Status

func (*Server) ContainerStart 

func (srv *Server) ContainerStart(job *engine.Job) engine.Status

func (*Server) ContainerStop 

func (srv *Server) ContainerStop(job *engine.Job) engine.Status

func (*Server) ContainerTop 

func (srv *Server) ContainerTop(job *engine.Job) engine.Status

func (*Server) ContainerWait 

func (srv *Server) ContainerWait(job *engine.Job) engine.Status

func (*Server) Containers 

func (srv *Server) Containers(job *engine.Job) engine.Status

func (*Server) DeleteImage 

func (srv *Server) DeleteImage(name string, imgs *engine.Table, first, force bool) error

func (*Server) DockerInfo 

func (srv *Server) DockerInfo(job *engine.Job) engine.Status

func (*Server) Events 

func (srv *Server) Events(job *engine.Job) engine.Status

func (*Server) GetEvents 

func (srv *Server) GetEvents() []utils.JSONMessage

func (*Server) HTTPRequestFactory 

func (srv *Server) HTTPRequestFactory(metaHeaders map[string][]string) *utils.HTTPRequestFactory

func (*Server) ImageDelete 

func (srv *Server) ImageDelete(job *engine.Job) engine.Status

func (*Server) ImageExport 

func (srv *Server) ImageExport(job *engine.Job) engine.Status

ImageExport exports all images with the given tag. All versions containing the same tag are exported. The resulting output is an uncompressed tar ball. name is the set of tags to export. out is the writer where the images are written to.

func (*Server) ImageGetCached 

func (srv *Server) ImageGetCached(imgID string, config *runconfig.Config) (*image.Image, error)

func (*Server) ImageHistory 

func (srv *Server) ImageHistory(job *engine.Job) engine.Status

func (*Server) ImageImport 

func (srv *Server) ImageImport(job *engine.Job) engine.Status

func (*Server) ImageInsert 

func (srv *Server) ImageInsert(job *engine.Job) engine.Status

func (*Server) ImageInspect 

func (srv *Server) ImageInspect(name string) (*image.Image, error)

func (*Server) ImageLoad 

func (srv *Server) ImageLoad(job *engine.Job) engine.Status

Loads a set of images into the repository. This is the complementary of ImageExport. The input stream is an uncompressed tar ball containing images and metadata.

func (*Server) ImagePull 

func (srv *Server) ImagePull(job *engine.Job) engine.Status

func (*Server) ImagePush 

func (srv *Server) ImagePush(job *engine.Job) engine.Status

FIXME: Allow to interrupt current push when new push of same image is done.

func (*Server) ImageTag 

func (srv *Server) ImageTag(job *engine.Job) engine.Status

func (*Server) Images 

func (srv *Server) Images(job *engine.Job) engine.Status

func (*Server) ImagesSearch 

func (srv *Server) ImagesSearch(job *engine.Job) engine.Status

func (*Server) ImagesViz 

func (srv *Server) ImagesViz(job *engine.Job) engine.Status

func (*Server) IsRunning 

func (srv *Server) IsRunning() bool

func (*Server) JobInspect 

func (srv *Server) JobInspect(job *engine.Job) engine.Status

func (*Server) LogEvent 

func (srv *Server) LogEvent(action, id, from string) *utils.JSONMessage
func (srv *Server) RegisterLinks(container *runtime.Container, hostConfig *runconfig.HostConfig) error

func (*Server) SetRunning 

func (srv *Server) SetRunning(status bool)

type StderrFormater 

type StderrFormater struct {
	io.Writer
	*utils.StreamFormatter
}

func (*StderrFormater) Write 

func (sf *StderrFormater) Write(buf []byte) (int, error)

type StdoutFormater 

type StdoutFormater struct {
	io.Writer
	*utils.StreamFormatter
}

func (*StdoutFormater) Write 

func (sf *StdoutFormater) Write(buf []byte) (int, error)

Source Files

View all Source files

Directories

Path Synopsis
docker-device-tool
host-integration
lxc
native
These types are wrappers around the libcontainer Terminal interface so that we can resuse the docker implementations where possible.
 These types are wrappers around the libcontainer Terminal interface so that we can resuse the docker implementations where possible.
aufs
btrfs
devmapper
vfs
ipallocator
lxc
portallocator
portmapper
pkg
cgroups
collections
graphdb
iptables
libcontainer
libcontainer/apparmor
libcontainer/capabilities
libcontainer/network
libcontainer/nsinit
libcontainer/nsinit/nsinit
libcontainer/utils
listenbuffer
Package to allow go applications to immediately start listening on a socket, unix, tcp, udp but hold connections until the application has booted and is ready to accept them
 Package to allow go applications to immediately start listening on a socket, unix, tcp, udp but hold connections until the application has booted and is ready to accept them
mflag
Package flag implements command-line flag parsing.
 Package flag implements command-line flag parsing.
mflag/example
mount
namesgenerator
netlink
Packet netlink provide access to low level Netlink sockets and messages.
 Packet netlink provide access to low level Netlink sockets and messages.
proxy
sysinfo
system
systemd
systemd/activation
term
user
version

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