moby--moby/docs/sources/index.md

page_title: About Docker page_description: Introduction to Docker. page_keywords: docker, introduction, documentation, about, technology, understanding, Dockerfile

About Docker

Develop, Ship and Run Any Application, Anywhere

Docker is a platform for developers and sysadmins to develop, ship, and run applications. Docker lets you quickly assemble applications from components and eliminates the friction that can come when shipping code. Docker lets you get your code tested and deployed into production as fast as possible.

Docker consists of:

• The Docker Engine - our lightweight and powerful open source container virtualization technology combined with a work flow for building and containerizing your applications.
• Docker Hub - our SaaS service for sharing and managing your application stacks.

Why Docker?

Faster delivery of your applications

• We want your environment to work better. Docker containers, and the work flow that comes with them, help your developers, sysadmins, QA folks, and release engineers work together to get your code into production and make it useful. We've created a standard container format that lets developers care about their applications inside containers while sysadmins and operators can work on running the container in your deployment. This separation of duties streamlines and simplifies the management and deployment of code.
• We make it easy to build new containers, enable rapid iteration of your applications, and increase the visibility of changes. This helps everyone in your organization understand how an application works and how it is built.
• Docker containers are lightweight and fast! Containers have sub-second launch times, reducing the cycle time of development, testing, and deployment.

Deploy and scale more easily

• Docker containers run (almost) everywhere. You can deploy containers on desktops, physical servers, virtual machines, into data centers, and up to public and private clouds.
• Since Docker runs on so many platforms, it's easy to move your applications around. You can easily move an application from a testing environment into the cloud and back whenever you need.
• Docker's lightweight containers also make scaling up and down fast and easy. You can quickly launch more containers when needed and then shut them down easily when they're no longer needed.

Get higher density and run more workloads

• Docker containers don't need a hypervisor, so you can pack more of them onto your hosts. This means you get more value out of every server and can potentially reduce what you spend on equipment and licenses.

Faster deployment makes for easier management

• As Docker speeds up your work flow, it gets easier to make lots of small changes instead of huge, big bang updates. Smaller changes mean reduced risk and more uptime.

About this guide

The Understanding Docker section will help you:

• See how Docker works at a high level
• Understand the architecture of Docker
• Discover Docker's features;
• See how Docker compares to virtual machines
• See some common use cases.

Installation Guides

The installation section will show you how to install Docker on a variety of platforms.

Docker User Guide

To learn about Docker in more detail and to answer questions about usage and implementation, check out the Docker User Guide.

Release Notes

Version 1.3.0

This version fixes a number of bugs and issues and adds new functions and other improvements. The GitHub 1.3 milestone has more detailed information. Major additions and changes include:

New command: docker exec

The new docker exec command lets you run a process in an existing, active container. The command has APIs for both the daemon and the client. With docker exec, you'll be able to do things like add or remove devices from running containers, debug running containers, and run commands that are not part of the container's static specification. Details in the command line reference.

New command: docker create

Traditionally, the docker run command has been used to both create a container and spawn a process to run it. The new docker create command breaks this apart, letting you set up a container without actually starting it. This provides more control over management of the container lifecycle, giving you the ability to configure things like volumes or port mappings before the container is started. For example, in a rapid-response scaling situation, you could use create to prepare and stage ten containers in anticipation of heavy loads. Details in the command line reference.

Tech preview of new provenance features

This release offers a sneak peek at new image signing capabilities that are currently under development. Soon, these capabilities will allow any image author to sign their images to certify they have not been tampered with. For this release, Official images are now signed by Docker, Inc. Not only does this demonstrate the new functionality, we hope it will improve your confidence in the security of Official images. Look for the blue ribbons denoting signed images on the Docker Hub. The Docker Engine has been updated to automatically verify that a given Official Repo has a current, valid signature. When pulling a signed image, you'll see a message stating the image you are pulling has been verified. If no valid signature is detected, Docker Engine will fall back to pulling a regular, unsigned image.

Other improvements & changes

• We've added a new security options flag to the docker run command, --security-opt, that lets you set SELinux and AppArmor labels and profiles. This means you'll no longer have to use docker run --privileged on kernels that support SE Linux or AppArmor. For more information, see the command line reference.

• A new flag, --add-host, has been added to docker run that lets you add lines to /etc/hosts. This allows you to specify different name resolution for the container than it would get via DNS. For more information, see the command line reference.

• You can now set a DOCKER_TLS_VERIFY environment variable to secure connections by default (rather than having to pass the --tlsverify flag on every call). For more information, see the https guide.

• Three security issues have been addressed in this release: CVE-2014-5280, CVE-2014-5270, and CVE-2014-5282.