Kernel Requirements
===================

If you want to have a full working CRUX+Docker system you will need to
rebuild your kernel and enable various networking, cgroups
and optional lvm options

You may check your kernel configuration by running:

::
    
    /usr/share/docker/check-config.sh
         
.. note:: If you receive an error such as "cgroup hierarchy: nonexistent??"
          then you should run ``cgroupfs-mount`` and re-run
          ``/usr/share/docker/check-config.sh``.
          
          Please follow the guideance of the output of
          ``/usr/share/docker/check-config.sh`` carefully.


Execution Engines
=================

As of Docker 0.9+ execution engines are pluggable and as such Docker
no longer depends on lxc.

The new default execution driver is now an internal ``libcontainer``
driver that replaces the need for lxc.

Please see the `Docker Documentation <http://docs.docker.io>`_
if you want to use a different execution engine other then the default.


Storage Backends
================

Docker comes with three main Storage Backends:

- AUFS (*requires AUFS kernel/patches*)
- devmapper
- btrfs

It is recommended you use the devmapper or btrfs backend (Default: devmapper).

To use the ``btrfs`` backend edit ``/etc/docker.conf``
and modify the ``DOCKER_OPTS`` with:

::
    
    DOCKER_OPTS="-s btrfs"
    
.. note:: As of Docker 0.10.x the ``btrfs`` storage backend is now
          considered stable and has been promoted to an officially
          supported storage backend.


Docker Client
=============

Add yourself to the ``docker`` group if you wish to access
the Docker daemon on localhost via UNIX Socket.