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@@ -9,40 +9,140 @@ FAQ
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Most frequently asked questions.
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-1. **How much does Docker cost?**
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+How much does Docker cost?
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+..........................
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Docker is 100% free, it is open source, so you can use it without paying.
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-2. **What open source license are you using?**
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-
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- We are using the Apache License Version 2.0, see it here: https://github.com/dotcloud/docker/blob/master/LICENSE
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-
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-3. **Does Docker run on Mac OS X or Windows?**
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-
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- Not at this time, Docker currently only runs on Linux, but you can use VirtualBox to run Docker in a
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- virtual machine on your box, and get the best of both worlds. Check out the :ref:`install_using_vagrant` and :ref:`windows` installation guides.
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-
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-4. **How do containers compare to virtual machines?**
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-
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- They are complementary. VMs are best used to allocate chunks of hardware resources. Containers operate at the process level, which makes them very lightweight and perfect as a unit of software delivery.
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-
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-5. **Can I help by adding some questions and answers?**
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+What open source license are you using?
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+.......................................
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+
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+ We are using the Apache License Version 2.0, see it here:
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+ https://github.com/dotcloud/docker/blob/master/LICENSE
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+
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+Does Docker run on Mac OS X or Windows?
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+.......................................
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+
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+ Not at this time, Docker currently only runs on Linux, but you can
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+ use VirtualBox to run Docker in a virtual machine on your box, and
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+ get the best of both worlds. Check out the
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+ :ref:`install_using_vagrant` and :ref:`windows` installation
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+ guides.
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+
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+How do containers compare to virtual machines?
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+..............................................
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+
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+ They are complementary. VMs are best used to allocate chunks of
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+ hardware resources. Containers operate at the process level, which
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+ makes them very lightweight and perfect as a unit of software
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+ delivery.
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+
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+What does Docker add to just plain LXC?
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+.......................................
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+
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+ Docker is not a replacement for LXC. "LXC" refers to capabilities
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+ of the Linux kernel (specifically namespaces and control groups)
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+ which allow sandboxing processes from one another, and controlling
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+ their resource allocations. On top of this low-level foundation of
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+ kernel features, Docker offers a high-level tool with several
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+ powerful functionalities:
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+
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+ * *Portable deployment across machines.*
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+ Docker defines a format for bundling an application and all its
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+ dependencies into a single object which can be transferred to
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+ any Docker-enabled machine, and executed there with the
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+ guarantee that the execution environment exposed to the
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+ application will be the same. LXC implements process sandboxing,
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+ which is an important pre-requisite for portable deployment, but
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+ that alone is not enough for portable deployment. If you sent me
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+ a copy of your application installed in a custom LXC
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+ configuration, it would almost certainly not run on my machine
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+ the way it does on yours, because it is tied to your machine's
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+ specific configuration: networking, storage, logging, distro,
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+ etc. Docker defines an abstraction for these machine-specific
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+ settings, so that the exact same Docker container can run -
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+ unchanged - on many different machines, with many different
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+ configurations.
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+
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+ * *Application-centric.*
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+ Docker is optimized for the deployment of applications, as
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+ opposed to machines. This is reflected in its API, user
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+ interface, design philosophy and documentation. By contrast, the
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+ ``lxc`` helper scripts focus on containers as lightweight
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+ machines - basically servers that boot faster and need less
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+ RAM. We think there's more to containers than just that.
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+
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+ * *Automatic build.*
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+ Docker includes :ref:`a tool for developers to automatically
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+ assemble a container from their source code <dockerbuilder>`,
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+ with full control over application dependencies, build tools,
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+ packaging etc. They are free to use ``make, maven, chef, puppet,
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+ salt,`` Debian packages, RPMs, source tarballs, or any
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+ combination of the above, regardless of the configuration of the
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+ machines.
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+
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+ * *Versioning.*
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+ Docker includes git-like capabilities for tracking successive
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+ versions of a container, inspecting the diff between versions,
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+ committing new versions, rolling back etc. The history also
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+ includes how a container was assembled and by whom, so you get
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+ full traceability from the production server all the way back to
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+ the upstream developer. Docker also implements incremental
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+ uploads and downloads, similar to ``git pull``, so new versions
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+ of a container can be transferred by only sending diffs.
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+
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+ * *Component re-use.*
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+ Any container can be used as a :ref:`"base image"
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+ <base_image_def>` to create more specialized components. This
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+ can be done manually or as part of an automated build. For
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+ example you can prepare the ideal Python environment, and use it
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+ as a base for 10 different applications. Your ideal Postgresql
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+ setup can be re-used for all your future projects. And so on.
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+
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+ * *Sharing.*
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+ Docker has access to a `public registry
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+ <http://index.docker.io>`_ where thousands of people have
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+ uploaded useful containers: anything from Redis, CouchDB,
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+ Postgres to IRC bouncers to Rails app servers to Hadoop to base
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+ images for various Linux distros. The :ref:`registry
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+ <registryindexspec>` also includes an official "standard
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+ library" of useful containers maintained by the Docker team. The
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+ registry itself is open-source, so anyone can deploy their own
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+ registry to store and transfer private containers, for internal
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+ server deployments for example.
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+
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+ * *Tool ecosystem.*
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+ Docker defines an API for automating and customizing the
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+ creation and deployment of containers. There are a huge number
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+ of tools integrating with Docker to extend its
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+ capabilities. PaaS-like deployment (Dokku, Deis, Flynn),
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+ multi-node orchestration (Maestro, Salt, Mesos, Openstack Nova),
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+ management dashboards (docker-ui, Openstack Horizon, Shipyard),
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+ configuration management (Chef, Puppet), continuous integration
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+ (Jenkins, Strider, Travis), etc. Docker is rapidly establishing
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+ itself as the standard for container-based tooling.
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+
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+Can I help by adding some questions and answers?
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+................................................
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Definitely! You can fork `the repo`_ and edit the documentation sources.
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-42. **Where can I find more answers?**
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+Where can I find more answers?
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+..............................
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You can find more answers on:
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- * `Docker club mailinglist`_
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+ * `Docker user mailinglist`_
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+ * `Docker developer mailinglist`_
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* `IRC, docker on freenode`_
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* `Github`_
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* `Ask questions on Stackoverflow`_
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* `Join the conversation on Twitter`_
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- .. _Docker club mailinglist: https://groups.google.com/d/forum/docker-club
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+ .. _Docker user mailinglist: https://groups.google.com/d/forum/docker-user
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+ .. _Docker developer mailinglist: https://groups.google.com/d/forum/docker-dev
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.. _the repo: http://www.github.com/dotcloud/docker
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.. _IRC, docker on freenode: irc://chat.freenode.net#docker
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.. _Github: http://www.github.com/dotcloud/docker
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Andy Rothfusz