@@ -28,9 +28,7 @@ pages:

 - ['index.md', 'About', 'Docker']

 - ['introduction/index.md', '**HIDDEN**']

 - ['introduction/understanding-docker.md', 'About', 'Understanding Docker']

-- ['introduction/technology.md', 'About', 'The Technology']

 - ['introduction/working-with-docker.md', 'About', 'Working with Docker']

-- ['introduction/get-docker.md', 'About', 'Get Docker']

 # Installation:

 - ['installation/index.md', '**HIDDEN**']

@@ -1,82 +1,99 @@

 page_title: About Docker

-page_description: Docker introduction home page

+page_description: Introduction to Docker.

 page_keywords: docker, introduction, documentation, about, technology, understanding, Dockerfile

 # About Docker

-*Secure And Portable Containers Made Easy*

+**Develop, Ship and Run Any Application, Anywhere**

 ## Introduction

-[**Docker**](https://www.docker.io) is a container based virtualization

-framework. Unlike traditional virtualization Docker is fast, lightweight

-and easy to use. Docker allows you to create containers holding

-all the dependencies for an application. Each container is kept isolated

-from any other, and nothing gets shared.

-

-## Docker highlights

-

- - **Containers provide sand-boxing:**  

-   Applications run securely without outside access.

- - **Docker allows simple portability:**  

-   Containers are directories, they can be zipped and transported.

- - **It all works fast:**  

-   Starting a container is a very fast single process.

- - **Docker is easy on the system resources (unlike VMs):**  

-   No more than what each application needs.

- - **Agnostic in its _essence_:**  

-   Free of framework, language or platform dependencies.

-

-And most importantly:

-

- - **Docker reduces complexity:**  

-   Docker accepts commands *in plain English*, e.g. `docker run [..]`.

+[**Docker**](https://www.docker.io) is a platform for developers and

+sysadmins to develop, ship, and run applications.  Docker consists of:

+

+* The Docker Engine - our lightweight and powerful open source container

+  virtualization technology combined with a work flow to help you build

+  and containerize your applications.

+* [Docker.io](https://index.docker.io) - our SAAS service that helps you

+  share and manage your applications stacks.

+

+Docker enables applications to be quickly assembled from components and

+eliminates the friction when shipping code. We want to help you get code

+from your desktop, tested and deployed into production as fast as

+possible.

+

+## Why Docker?

+

+- **Faster delivery of your applications**  

+    * We want to help your environment work better. Docker containers,

+      and the work flow that comes with them, helps your developers,

+      sysadmins, QA folks, and release engineers all work together to get code

+      into production and doing something useful. We've created a standard

+      container format that allows developers to care about their applications

+      inside containers and sysadmins and operators to care about running the

+      container. This creates a separation of duties that makes managing and

+      deploying code much easier and much more streamlined.

+    * We make it easy to build new containers and expose how each rapid

+      iterations and updates as well as visibility of changes.

+      container is built. 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! With containers you can reduce the cycle

+      time in development, testing and deployment.

+

+- **Deploy and scale more easily**  

+    * Docker containers run (almost!) everywhere. You can deploy your

+      containers on desktops, physical servers, virtual machines, into

+      data centers and to public and private cloud.

+    * As Docker runs on so many platforms it makes it easy to move your

+      appications around. You can easily move an application from a

+      testing environment into the cloud and back whenever you need.

+    * The lightweight containers Docker creates also making scaling and

+      down really fast and easy. If you need more containers you can

+      quickly launch them and then shut them down when you don't need them

+      anymore.

+

+- **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 the money you spend on equipment and

+      licenses!

+

+- **Faster deployment makes for easier management**  

+    * As Docker speeds up your work flow it makes it easier to make lots

+      of little changes instead of huge, big bang updates. Smaller

+      changes mean smaller risks and mean more uptime!

 ## About this guide

-In this introduction we will take you on a tour and show you what

-makes Docker tick.

-

-On the [**first page**](introduction/understanding-docker.md), which is

-**_informative_**:

-

- - You will find information on Docker;

- - And discover Docker's features.

- - We will also compare Docker to virtual machines;

- - And see some common use cases.

-

-> [Click here to go to Understanding Docker](introduction/understanding-docker.md).

-

-The [**second page**](introduction/technology.md) has **_technical_** information on:

+First we'll show you [what makes Docker tick in our Understanding Docker

+section](introduction/understanding-docker.md):

+ - You will find see how Docker works at a high level;

  - The architecture of Docker;

- - The underlying technology, and;

- - *How* Docker works.

-

-> [Click here to go to Understanding the Technology](introduction/technology.md).

-

-On the [**third page**](introduction/working-with-docker.md) we get **_practical_**.

-There you can:

+ - Discover Docker's features;

+ - See how Docker compares to virtual machines;

+ - And see some common use cases.

- - Learn about Docker's components (i.e. Containers, Images and the

-   Dockerfile);

- - And get started working with them straight away.

+> [Click here to go to the Understanding

+> Docker section](introduction/understanding-docker.md).

-> [Click here to go to Working with Docker](introduction/working-with-docker.md).

+Next we get [**practical** with the Working with Docker

+section](introduction/working-with-docker.md) and you can learn about:

-Finally, on the [**fourth**](introduction/get-docker.md) page, we go **_hands on_**

-and see:

+ - Docker on the command line;

+ - Get introduced to your first Docker commands;

+ - Get to know your way around the basics of Docker operation.

- - The installation instructions, and;

- - How Docker makes some hard problems much, much easier.

+> [Click here to go to the Working with

+> Docker section](introduction/working-with-docker.md).

-> [Click here to go to Get Docker](introduction/get-docker.md).

+If you want to see how to install Docker you can jump to the

+[installation](/installation/#installation) section.

 > **Note**:

-> We know how valuable your time is. Therefore, the documentation is prepared

-> in a way to allow anyone to start from any section need. Although we strongly

-> recommend that you visit [Understanding Docker](

-> introduction/understanding-docker.md) to see how Docker is different, if you

-> already have some knowledge and want to quickly get started with Docker,

-> don't hesitate to jump to [Working with Docker](

-> introduction/working-with-docker.md).

+> We know how valuable your time is so you if you want to get started

+> with Docker straight away don't hesitate to jump to [Working with

+> Docker](introduction/working-with-docker.md). For a fuller

+> understanding of Docker though we do recommend you read [Understanding

+> Docker]( introduction/understanding-docker.md).

deleted file mode 100644

@@ -1,77 +0,0 @@

-page_title: Getting Docker

-page_description: Getting Docker and installation tutorials

-page_keywords: docker, introduction, documentation, about, technology, understanding, Dockerfile

-

-# Getting Docker

-

-*How to install Docker?*

-

-## Introductions

-

-Once you are comfortable with your level of knowledge of Docker, and

-feel like actually trying the product, you can download and start using

-it by following the links listed below. There, you will find

-installation instructions, specifically tailored for your platform of choice.

-

-## Installation Instructions

-

-### Linux (Native)

-

- - **Arch Linux:**  

- [Installation on Arch Linux](../installation/archlinux.md)

- - **Fedora:**  

- [Installation on Fedora](../installation/fedora.md)

- - **FrugalWare:**  

- [Installation on FrugalWare](../installation/frugalware.md)

- - **Gentoo:**  

- [Installation on Gentoo](../installation/gentoolinux.md)

- - **Red Hat Enterprise Linux:**

- [Installation on Red Hat Enterprise Linux](../installation/rhel.md)

- - **Ubuntu:**  

- [Installation on Ubuntu](../installation/ubuntulinux.md)

- - **openSUSE:**  

- [Installation on openSUSE](../installation/openSUSE.md)

-

-### Mac OS X (Using Boot2Docker)

-

-In order to work, Docker makes use of some Linux Kernel features which

-are not supported by Mac OS X. To run Docker on OS X we install and run

-a lightweight virtual machine and run Docker on that.

-

- - **Mac OS X :**  

- [Installation on Mac OS X](../installation/mac.md)

-

-### Windows (Using Boot2Docker)

-

-Docker can also run on Windows using a virtual machine. You then run

-Linux and Docker inside that virtual machine.

-

- - **Windows:**  

- [Installation on Windows](../installation/windows.md)

-

-### Infrastructure-as-a-Service

-

- - **Amazon EC2:**  

- [Installation on Amazon EC2](../installation/amazon.md)

- - **Google Cloud Platform:**  

- [Installation on Google Cloud Platform](../installation/google.md)

- - **Rackspace Cloud:**  

- [Installation on Rackspace Cloud](../installation/rackspace.md)

-

-## Where to go from here

-

-### Understanding Docker

-

-Visit [Understanding Docker](understanding-docker.md) in our Getting Started manual.

-

-### Learn about parts of Docker and the underlying technology

-

-Visit [Understanding the Technology](technology.md) in our Getting Started manual.

-

-### Get practical and learn how to use Docker straight away

-

-Visit [Working with Docker](working-with-docker.md) in our Getting Started manual.

-

-### Get the whole story

-

-[https://www.docker.io/the_whole_story/](https://www.docker.io/the_whole_story/)

deleted file mode 100644

@@ -1,268 +0,0 @@

-page_title: Understanding the Technology

-page_description: Technology of Docker explained in depth

-page_keywords: docker, introduction, documentation, about, technology, understanding, Dockerfile

-

-# Understanding the Technology

-

-*What is the architecture of Docker? What is its underlying technology?*

-

-## Introduction

-

-When it comes to understanding Docker and its underlying technology

-there is no *magic* involved. Everything is based on tried and tested

-features of the *Linux kernel*. Docker either makes use of those

-features directly or builds upon them to provide new functionality.

-

-Aside from the technology, one of the major factors that make Docker

-great is the way it is built. The project's core is very lightweight and

-as much of Docker as possible is designed to be pluggable. Docker is

-also built with integration in mind and has a fully featured API that

-allows you to access all of the power of Docker from inside your own

-applications.

-

-## The Architecture of Docker

-

-Docker is designed for developers and sysadmins. It's built to help you

-build applications and services and then deploy them quickly and

-efficiently: from development to production.

-

-Let's take a look.

-

-

-![Docker Architecture Diagram](/article-img/architecture.svg)

-

-## The components of Docker

-

-Docker's main components are:

-

- - Docker *daemon*;

- - Docker *client*, and;

- - [Docker.io](https://index.docker.io) registry.

-

-### The Docker daemon

-

-As shown on the diagram above, the Docker daemon runs on a host machine.

-The user does not directly interact with the daemon, but instead through

-an intermediary: the Docker client.

-

-### Docker client

-

-The Docker client is the primary user interface to Docker. It is tasked

-with accepting commands from the user and communicating back and forth

-with a Docker daemon to manage the container lifecycle on any host.

-

-### Docker.io registry

-

-[Docker.io](https://index.docker.io) is the global archive (and

-directory) of user supplied Docker container images. It currently hosts

-a large – in fact, rapidly growing – number of projects where you

-can find almost any popular application or deployment stack readily

-available to download and run with a single command.

-

-As a social community project, Docker tries to provide all necessary

-tools for everyone to grow with other *Dockers*. By issuing a single

-command through the Docker client you can start sharing your own

-creations with the rest of the world.

-

-However, knowing that not everything can be shared the [Docker.io](

-https://index.docker.io) also offers private repositories. In order to see

-the available plans, you can click [here](https://index.docker.io/plans).

-

-Using [*docker-registry*](https://github.com/dotcloud/docker-registry), it is

-also possible to run your own private Docker image registry service on your own

-servers.

-

-> **Note:** To learn more about the [*Docker.io*](http://index.docker.io)

-> registry (for public *and* private repositories), check out the [Registry &

-> Index Spec](http://docs.docker.io/api/registry_index_spec/).

-

-### Summary

-

- - **When you install Docker, you get all the components:**  

- The daemon, the client and access to the [Docker.io](http://index.docker.io) registry.

- - **You can run these components together or distributed:**  

- Servers with the Docker daemon running, controlled by the Docker client.

- - **You can benefit form the public registry:**  

- Download and build upon images created by the community.

- - **You can start a private repository for proprietary use.**  

- Sign up for a [plan](https://index.docker.io/plans) or host your own [docker-registry](

-https://github.com/dotcloud/docker-registry).

-

-## Elements of Docker

-

-The basic elements of Docker are:

-

- - **Containers, which allow:**  

- The run portion of Docker. Your applications run inside of containers.

- - **Images, which provide:**  

- The build portion of Docker. Your containers are built from images.

- - **The Dockerfile, which automates:**  

- A file that contains simple instructions that build Docker images.

-

-To get practical and learn what they are, and **_how to work_** with

-them, continue to [Working with Docker](working-with-docker.md). If you would like to

-understand **_how they work_**, stay here and continue reading.

-

-## The underlying technology

-

-The power of Docker comes from the underlying technology it is built

-from. A series of operating system features are carefully glued together

-to provide Docker's features and provide an easy to use interface to

-those features. In this section, we will see the main operating system

-features that Docker uses to make easy containerization happen.

-

-### Namespaces

-

-Docker takes advantage of a technology called `namespaces` to provide

-an isolated workspace we call a *container*.  When you run a container,

-Docker creates a set of *namespaces* for that container.

-

-This provides a layer of isolation: each process runs in its own

-namespace and does not have access outside it.

-

-Some of the namespaces Docker uses are:

-

- - **The `pid` namespace:**  

- Used for process numbering (PID: Process ID)

- - **The `net` namespace:**  

- Used for managing network interfaces (NET: Networking)

- - **The `ipc` namespace:**  

- Used for managing access to IPC resources (IPC: InterProcess Communication)

- - **The `mnt` namespace:**  

- Used for managing mount-points (MNT: Mount)

- - **The `uts` namespace:**  

- Used for isolating kernel / version identifiers. (UTS: Unix Timesharing System)

-

-### Control groups

-

-Docker also makes use of another technology called `cgroups` or control

-groups. A key need to run applications in isolation is to have them

-contained, not just in terms of related filesystem and/or dependencies,

-but also, resources. Control groups allow Docker to fairly

-share available hardware resources to containers and if asked, set up to

-limits and constraints, for example limiting the memory to a maximum of 128

-MBs.

-

-### UnionFS

-

-UnionFS or union filesystems are filesystems that operate by creating

-layers, making them very lightweight and fast. Docker uses union

-filesystems to provide the building blocks for containers. We'll see

-more about this below.

-

-### Containers

-

-Docker combines these components to build a container format we call

-`libcontainer`. Docker also supports traditional Linux containers like

-[LXC](https://linuxcontainers.org/) which also make use of these

-components.

-

-## How does everything work

-

-A lot happens when Docker creates a container.

-

-Let's see how it works!

-

-### How does a container work?

-

-A container consists of an operating system, user added files and

-meta-data. Each container is built from an image. That image tells

-Docker what the container holds, what process to run when the container

-is launched and a variety of other configuration data. The Docker image

-is read-only. When Docker runs a container from an image it adds a

-read-write layer on top of the image (using the UnionFS technology we

-saw earlier) to run inside the container.

-

-### What happens when you run a container?

-

-The Docker client (or the API!) tells the Docker daemon to run a

-container. Let's take a look at a simple `Hello world` example.

-

-    $ docker run -i -t ubuntu /bin/bash

-

-Let's break down this command. The Docker client is launched using the

-`docker` binary. The bare minimum the Docker client needs to tell the

-Docker daemon is:

-

-* What Docker image to build the container from;

-* The command you want to run inside the container when it is launched.

-

-So what happens under the covers when we run this command?

-

-Docker begins with:

-

- - **Pulling the `ubuntu` image:**  

- Docker checks for the presence of the `ubuntu` image and if it doesn't

- exist locally on the host, then Docker downloads it from [Docker.io](https://index.docker.io)

- - **Creates a new container:**  

- Once Docker has the image it creates a container from it.

- - **Allocates a filesystem and mounts a read-write _layer_:**  

- The container is created in the filesystem and a read-write layer is added to the image.

- - **Allocates a network / bridge interface:**  

- Creates a network interface that allows the Docker container to talk to the local host.

- - **Sets up an IP address:**  

- Intelligently finds and attaches an available IP address from a pool.

- - **Executes _a_ process that you specify:**  

- Runs your application, and;

- - **Captures and provides application output:**  

- Connects and logs standard input, outputs and errors for you to see how your application is running.

-

-### How does a Docker Image work?

-

-We've already seen that Docker images are read-only templates that

-Docker containers are launched from. When you launch that container it

-creates a read-write layer on top of that image that your application is

-run in.

-

-Docker images are built using a simple descriptive set of steps we

-call *instructions*. Instructions are stored in a file called a

-`Dockerfile`. Each instruction writes a new layer to an image using the

-UnionFS technology we saw earlier.

-

-Every image starts from a base image, for example `ubuntu` a base Ubuntu

-image or `fedora` a base Fedora image. Docker builds and provides these

-base images via [Docker.io](http://index.docker.io).

-

-### How does a Docker registry work?

-

-The Docker registry is a store for your Docker images. Once you build a

-Docker image you can *push* it to a public or private repository on [Docker.io](

-http://index.docker.io) or to your own registry running behind your firewall.

-

-Using the Docker client, you can search for already published images and

-then pull them down to your Docker host to build containers from them

-(or even build on these images).

-

-[Docker.io](http://index.docker.io) provides both public and

-private storage for images. Public storage is searchable and can be

-downloaded by anyone. Private repositories are excluded from search

-results and only you and your users can pull them down and use them to

-build containers. You can [sign up for a plan here](https://index.docker.io/plans).

-

-To learn more, check out the [Working with Repositories](

-http://docs.docker.io/use/workingwithrepository) section from the

-[Docker documentation](http://docs.docker.io).

-

-## Where to go from here

-

-### Understanding Docker

-

-Visit [Understanding Docker](understanding-docker.md) in our Getting Started manual.

-

-### Get practical and learn how to use Docker straight away

-

-Visit [Working with Docker](working-with-docker.md) in our Getting Started manual.

-

-### Get the product and go hands-on

-

-Visit [Get Docker](get-docker.md) in our Getting Started manual.

-

-### Get the whole story

-

-[https://www.docker.io/the_whole_story/](https://www.docker.io/the_whole_story/)

@@ -1,272 +1,331 @@

 page_title: Understanding Docker

 page_description: Docker explained in depth

-page_keywords: docker, introduction, documentation, about, technology, understanding, Dockerfile

+page_keywords: docker, introduction, documentation, about, technology, understanding

 # Understanding Docker

-*What is Docker? What makes it great?*

+**What is Docker?**

-Building development lifecycles, pipelines and deployment tooling is

-hard. It's not easy to create portable applications and services.

-There's often high friction getting code from your development

-environment to production. It's also hard to ensure those applications

-and services are consistent, up-to-date and managed.

+Docker is a platform for developing, shipping, and running applications.

+Docker is designed to deliver your applications faster.  With Docker you

+can separate your applications from your infrastructure AND treat your

+infrastructure like a managed application. We want to help you ship code

+faster, test faster, deploy faster and shorten the cycle between writing

+code and running code.

-Docker is designed to solve these problem for both developers and

-sysadmins. It is a lightweight framework (with a powerful API) that

-provides a lifecycle for building and deploying applications into

-containers.

+Docker does this by combining a lightweight container virtualization

+platform with workflow and tooling that helps you manage and deploy your

+applications.

-Docker provides a way to run almost any application securely isolated

-into a container. The isolation and security allows you to run many

-containers simultaneously on your host. The lightweight nature of

+At its core Docker provides a way to run almost any application securely

+isolated into a container. The isolation and security allows you to run

+many containers simultaneously on your host. The lightweight nature of

 containers, which run without the extra overload of a hypervisor, means

 you can get more out of your hardware.

-**Note:** Docker itself is *shipped* with the Apache 2.0 license and it

-is completely open-source — *the pun? very much intended*.

+Surrounding the container virtualization, we provide tooling and a

+platform to help you get your applications (and its supporting

+components) into Docker containers, to distribute and ship those

+containers to your teams to develop and test on them and then to deploy

+those applications to your production environment whether it be in a

+local data center or the Cloud.

-### What are the Docker basics I need to know?

+## What can I use Docker for?

-Docker has three major components:

+* Faster delivery of your applications

-* Docker containers.

-* Docker images.

-* Docker registries.

-

-#### Docker containers

-

-Docker containers are like a directory. A Docker container holds

-everything that is needed for an application to run. Each container is

-created from a Docker image. Docker containers can be run, started,

-stopped, moved and deleted. Each container is an isolated and secure

-application platform. You can consider Docker containers the *run*

-portion of the Docker framework.

-

-#### Docker images

-

-The Docker image is a template, for example an Ubuntu

-operating system with Apache and your web application installed. Docker

-containers are launched from images. Docker provides a simple way to

-build new images or update existing images. You can consider Docker

-images to be the *build* portion of the Docker framework.

-

-#### Docker Registries

-

-Docker registries hold images. These are public (or private!) stores

-that you can upload or download images to and from. These images can be

-images you create yourself or you can make use of images that others

-have previously created. Docker registries allow you to build simple and

-powerful development and deployment work flows. You can consider Docker

-registries the *share* portion of the Docker framework.

-

-### How does Docker work?

-

-Docker is a client-server framework. The Docker *client* commands the Docker

-*daemon*, which in turn creates, builds and manages containers.

-

-The Docker daemon takes advantage of some neat Linux kernel and

-operating system features, like `namespaces` and `cgroups`, to build

-isolated container. Docker provides a simple abstraction layer to these

-technologies.

-

-> **Note:** If you would like to learn more about the underlying technology,

-> why not jump to [Understanding the Technology](technology.md) where we talk about them? You can

-> always come back here to continue learning about features of Docker and what

-> makes it different.

-

-## Features of Docker

-

-In order to get a good grasp of the capabilities of Docker you should

-read the [User's Manual](http://docs.docker.io). Let's look at a summary

-of Docker's features to give you an idea of how Docker might be useful

-to you.

-

-### User centric and simple to use

-

-*Docker is made for humans.*

-

-It's easy to get started and easy to build and deploy applications with

-Docker: or as we say "*dockerize*" them! As much of Docker as possible

-uses plain English for commands and tries to be as lightweight and

-transparent as possible. We want to get out of the way so you can build

-and deploy your applications.

-

-### Docker is Portable

-

-*Dockerize And Go!*

-

-Docker containers are highly portable. Docker provides a standard

-container format to hold your applications:

-

-* You take care of your applications inside the container, and;

-* Docker takes care of managing the container.

-

-Any machine, be it bare-metal or virtualized, can run any Docker

-container. The sole requirement is to have Docker installed.

-

-**This translates to:**

+Docker is perfect for helping you with the development lifecycle. Docker

+can allow your developers to develop on local containers that contain

+your applications and services. It can integrate into a continuous

+integration and deployment workflow.

- - Reliability;

- - Freeing your applications out of the dependency-hell;

- - A natural guarantee that things will work, anywhere.

+Your developers write code locally and share their development stack via

+Docker with their colleagues. When they are ready they can push their

+code and the stack they are developing on to a test environment and

+execute any required tests. From the testing environment you can then

+push your Docker images into production and deploy your code.

-### Lightweight

+* Deploy and scale more easily

-*No more resources waste.*

+Docker's container platform allows you to have highly portable

+workloads. Docker containers can run on a developer's local host, on

+physical or virtual machines in a data center or in the Cloud.

-Containers are lightweight, in fact, they are extremely lightweight.

-Unlike traditional virtual machines, which have the overhead of a

-hypervisor, Docker relies on operating system level features to provide

-isolation and security. A Docker container does not need anything more

-than what your application needs to run.

+Docker's portability and lightweight nature also makes managing

+workloads dynamically easy. You can use Docker to build and scale out

+applications and services. Docker's speed means that scaling can be near

+real time.

-This translates to:

+* Get higher density and run more workloads

- - Ability to deploy a large number of applications on a single system;

- - Lightning fast start up times and reduced overhead.

+Docker is lightweight and fast. It provides a viable (and

+cost-effective!) alternative to hypervisor-based virtual machines. This

+is especially useful in high density environments, for example building

+your own Cloud or Platform-as-a-Service. But it is also useful

+for small and medium deployments where you want to get more out of the

+resources you have.

-### Docker can run anything

+## What are the major Docker components?

-*An amazing host! (again, pun intended.)*

+Docker has two major components:

-Docker isn't prescriptive about what applications or services you can run

-inside containers. We provide use cases and examples for running web

-services, databases, applications - just about anything you can imagine

-can run in a Docker container.

+* Docker: the open source container virtualization platform.

+* [Docker.io](https://index.docker.io): our Software-as-a-Service

+  platform for sharing and managing Docker containers.

-**This translates to:**

+**Note:** Docker is licensed with the open source Apache 2.0 license.

- - Ability to run a wide range of applications;

- - Ability to deploy reliably without repeating yourself.

+## What is the architecture of Docker?

-### Plays well with others

+Docker has a client-server architecture. The Docker *client* talks to

+the Docker *daemon* which does the heavy lifting of building, running

+and distributing your Docker containers. Both the Docker client and the

+daemon *can* run on the same system, or you can connect a Docker client

+with a remote Docker daemon. The Docker client and service can

+communicate via sockets or through a RESTful API.

-*A wonderful guest.*

+![Docker Architecture Diagram](/article-img/architecture.svg)

-Today, it is possible to install and use Docker almost anywhere. Even on

-non-Linux systems such as Windows or Mac OS X thanks to a project called

-[Boot2Docker](http://boot2docker.io).

+### The Docker daemon

-**This translates to running Docker (and Docker containers!) _anywhere_:**

+As shown on the diagram above, the Docker daemon runs on a host machine.

+The user does not directly interact with the daemon, but instead through

+the Docker client.

- - **Linux:**  

- Ubuntu, CentOS / RHEL, Fedora, Gentoo, openSUSE and more.

- - **Infrastructure-as-a-Service:**  

- Amazon AWS, Google GCE, Rackspace Cloud and probably, your favorite IaaS.

- - **Microsoft Windows**  

- - **OS X**  

+### The Docker client

-### Docker is Responsible

+The Docker client, in the form of the `docker` binary, is the primary user

+interface to Docker. It is tasked with accepting commands from the user

+and communicating back and forth with a Docker daemon.

-*A tool that you can trust.*

+### Inside Docker

-Docker does not just bring you a set of tools to isolate and run

-applications. It also allows you to specify constraints and controls on

-those resources.

+Inside Docker there are three concepts we’ll need to understand:

-**This translates to:**

-

- - Fine tuning available resources for each application;

- - Allocating memory or CPU intelligently to make most of your environment;

-

-Without dealing with complicated commands or third party applications.

-

-### Docker is Social

-

-*Docker knows that No One Is an Island.*

-

-Docker allows you to share the images you've built with the world. And

-lots of people have already shared their own images.

-

-To facilitate this sharing Docker comes with a public registry called 

-[Docker.io](http://index.docker.io). If you don't want your images to be

-public you can also use private images on [Docker.io](https://index.docker.io)

-or even run your own registry behind your firewall.

-

-**This translates to:**

-

- - No more wasting time building everything from scratch;

- - Easily and quickly save your application stack;

- - Share and benefit from the depth of the Docker community.

-

-## Docker versus Virtual Machines

-

-> I suppose it is tempting, if the *only* tool you have is a hammer, to

-> treat *everything* as if it were a nail.

-> — **_Abraham Maslow_**

-

-**Docker containers are:**

-

- - Easy on the resources;

- - Extremely light to deal with;

- - Do not come with substantial overhead;

- - Very easy to work with;

- - Agnostic;

- - Can work *on* virtual machines;

- - Secure and isolated;

- - *Artful*, *social*, *fun*, and;

- - Powerful sand-boxes.

-

-**Docker containers are not:**

-

- - Hardware or OS emulators;

- - Resource heavy;

- - Platform, software or language dependent.

-

-## Docker Use Cases

-

-Docker is a framework. As a result it's flexible and powerful enough to

-be used in a lot of different use cases.

-

-### For developers

-

- - **Developed with developers in mind:**  

- Build, test and ship applications with nothing but Docker and lean

- containers.

- - **Re-usable building blocks to create more:**  

- Docker images are easily updated building blocks.

- - **Automatically build-able:**  

- It has never been this easy to build - *anything*.

- - **Easy to integrate:**  

- A powerful, fully featured API allows you to integrate Docker into your tooling.

-

-### For sysadmins

-

- - **Efficient (and DevOps friendly!) lifecycle:**  

- Operations and developments are consistent, repeatable and reliable.

- - **Balanced environments:**  

- Processes between development, testing and production are leveled.

- - **Improvements on speed and integration:**  

- Containers are almost nothing more than isolated, secure processes.

- - **Lowered costs of infrastructure:**  

- Containers are lightweight and heavy on resources compared to virtual machines.

- - **Portable configurations:**  

- Issues and overheads with dealing with configurations and systems are eliminated.

+* Docker images.

+* Docker registries.

+* Docker containers.

-### For everyone

+#### Docker images

- - **Increased security without performance loss:**  

- Replacing VMs with containers provide security without additional

- hardware (or software).

- - **Portable:**  

- You can easily move applications and workloads from different operating

- systems and platforms.

+The Docker image is a read-only template, for example an Ubuntu operating system

+with Apache and your web application installed. Docker containers are

+created from images. You can download Docker images that other people

+have created or Docker provides a simple way to build new images or

+update existing images. You can consider Docker images to be the **build**

+portion of Docker.

-## Where to go from here

+#### Docker Registries

-### Learn about Parts of Docker and the underlying technology

+Docker registries hold images. These are public (or private!) stores

+that you can upload or download images to and from. The public Docker

+registry is called [Docker.io](http://index.docker.io). It provides a

+huge collection of existing images that you can use. These images can be

+images you create yourself or you can make use of images that others

+have previously created. You can consider Docker registries the

+**distribution** portion of Docker.

-Visit [Understanding the Technology](technology.md) in our Getting Started manual.

+#### Docker containers

-### Get practical and learn how to use Docker straight away

+Docker containers are like a directory. A Docker container holds

+everything that is needed for an application to run. Each container is

+created from a Docker image. Docker containers can be run, started,

+stopped, moved and deleted. Each container is an isolated and secure

+application platform. You can consider Docker containers the **run**

+portion of Docker.

-Visit [Working with Docker](working-with-docker.md) in our Getting Started manual.

+## So how does Docker work?