Add Gentoo documentation

docs/sources/installation/gentoolinux.rst

@@ -0,0 +1,98 @@
+:title: Installation on Gentoo Linux
+:description: Docker installation instructions and nuances for Gentoo Linux.
+:keywords: gentoo linux, virtualization, docker, documentation, installation
+
+.. _gentoo_linux:
+
+Gentoo Linux
+============
+
+.. include:: install_header.inc
+
+.. include:: install_unofficial.inc
+
+Installing Docker on Gentoo Linux can be accomplished by using the overlay provided at https://github.com/tianon/docker-overlay.  The most up-to-date documentation for properly installing the overlay can be found in the overlay README.  The information here is provided for reference, and may be out of date.
+
+Installation
+^^^^^^^^^^^^
+
+Ensure that layman is installed:
+
+.. code-block:: bash
+
+   sudo emerge -av app-portage/layman
+
+Using your favorite editor, add ``https://raw.github.com/tianon/docker-overlay/master/repositories.xml`` to the ``overlays`` section in ``/etc/layman/layman.cfg`` (as per instructions on the `Gentoo Wiki <http://wiki.gentoo.org/wiki/Layman#Adding_custom_overlays>`_), then invoke the following:
+
+.. code-block:: bash
+
+   sudo layman -f -a docker
+
+Once that completes, the ``app-emulation/lxc-docker`` package will be available for emerge:
+
+.. code-block:: bash
+
+   sudo emerge -av app-emulation/lxc-docker
+
+If you prefer to use the official binaries, or just do not wish to compile docker, emerge ``app-emulation/lxc-docker-bin`` instead.  It is important to remember that Gentoo is still an unsupported platform, even when using the official binaries.
+
+The package should already include all the necessary dependencies.  For the simplest installation experiece, use ``sys-kernel/aufs-sources`` directly as your kernel sources.  If you prefer not to use ``sys-kernel/aufs-sources``, the portage tree also contains ``sys-fs/aufs3``, which contains the patches necessary for adding AUFS support to other kernel source packages (and a ``kernel-patch`` use flag to perform the patching automatically).
+
+Between ``app-emulation/lxc`` and ``app-emulation/lxc-docker``, all the necessary kernel configuration flags should be checked for and warned about in the standard manner.
+
+If any issues arise from this ebuild or the resulting binary, including and especially missing kernel configuration flags and/or dependencies, `open an issue <https://github.com/tianon/docker-overlay/issues>`_ on the docker-overlay repository or ping tianon in the #docker IRC channel.
+
+Starting Docker
+^^^^^^^^^^^^^^^
+
+Ensure that you are running a kernel that includes the necessary AUFS support and includes all the necessary modules and/or configuration for LXC.
+
+OpenRC
+------
+
+To start the docker daemon:
+
+.. code-block:: bash
+
+   sudo /etc/init.d/docker start
+
+To start on system boot:
+
+.. code-block:: bash
+
+   sudo rc-update add docker default
+
+systemd
+-------
+
+To start the docker daemon:
+
+.. code-block:: bash
+
+   sudo systemctl start docker.service
+
+To start on system boot:
+
+.. code-block:: bash
+
+   sudo systemctl enable docker.service
+
+Network Configuration
+^^^^^^^^^^^^^^^^^^^^^
+
+IPv4 packet forwarding is disabled by default, so internet access from inside the container will not work unless ``net.ipv4.ip_forward`` is enabled:
+
+.. code-block:: bash
+
+   sudo sysctl -w net.ipv4.ip_forward=1
+
+Or, to enable it more permanently:
+
+.. code-block:: bash
+
+   echo net.ipv4.ip_forward = 1 | sudo tee /etc/sysctl.d/docker.conf
+
+fork/exec /usr/sbin/lxc-start: operation not permitted
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Unfortunately, Gentoo suffers from `issue #1422 <https://github.com/dotcloud/docker/issues/1422>`_, meaning that after every fresh start of docker, the first docker run fails due to some tricky terminal issues, so be sure to run something trivial (such as ``docker run -i -t busybox echo hi``) before attempting to run anything important.

docs/sources/installation/index.rst

@@ -24,5 +24,6 @@ Contents:
    amazon
    rackspace
    archlinux
+   gentoolinux
    upgrading
    kernel