Merge "Add guide on running devstack in lxc container"

doc/source/guides/lxc.rst

@@ -0,0 +1,164 @@
+================================
+All-In-One Single LXC Container
+================================
+
+This guide walks you through the process of deploying OpenStack using devstack
+in an LXC container instead of a VM.
+
+The primary benefits to running devstack inside a container instead of a VM is
+faster performance and lower memory overhead while still providing a suitable
+level of isolation. This can be particularly useful when you want to simulate
+running OpenStack on multiple nodes.
+
+.. Warning:: Containers do not provide the same level of isolation as a virtual
+   machine.
+
+.. Note:: Not all OpenStack features support running inside of a container. See
+   `Limitations`_ section below for details. :doc:`OpenStack in a VM <single-vm>`
+   is recommended for beginners.
+
+Prerequisites
+==============
+
+This guide is written for Ubuntu 14.04 but should be adaptable for any modern
+Linux distribution.
+
+Install the LXC package::
+
+   sudo apt-get install lxc
+
+You can verify support for containerization features in your currently running
+kernel using the ``lxc-checkconfig`` command.
+
+Container Setup
+===============
+
+Configuration
+---------------
+
+For a successful run of ``stack.sh`` and to permit use of KVM to run the VMs you
+launch inside your container, we need to use the following additional
+configuration options. Place the following in a file called
+``devstack-lxc.conf``::
+
+  # Permit access to /dev/loop*
+  lxc.cgroup.devices.allow = b 7:* rwm
+  
+  # Setup access to /dev/net/tun and /dev/kvm
+  lxc.mount.entry = /dev/net/tun dev/net/tun none bind,create=file 0 0
+  lxc.mount.entry = /dev/kvm dev/kvm none bind,create=file 0 0
+  
+  # Networking
+  lxc.network.type = veth
+  lxc.network.flags = up
+  lxc.network.link = lxcbr0
+
+
+Create Container
+-------------------
+
+The configuration and rootfs for LXC containers are created using the
+``lxc-create`` command.
+
+We will name our container ``devstack`` and use the ``ubuntu`` template which
+will use ``debootstrap`` to build a Ubuntu rootfs. It will default to the same
+release and architecture as the host system. We also install the additional
+packages ``bsdmainutils`` and ``git`` as we'll need them to run devstack::
+
+  sudo lxc-create -n devstack -t ubuntu -f devstack-lxc.conf -- --packages=bsdmainutils,git
+
+The first time it builds the rootfs will take a few minutes to download, unpack,
+and configure all the necessary packages for a minimal installation of Ubuntu.
+LXC will cache this and subsequent containers will only take seconds to create.
+
+.. Note:: To speed up the initial rootfs creation, you can specify a mirror to
+   download the Ubuntu packages from by appending ``--mirror=`` and then the URL
+   of a Ubuntu mirror. To see other other template options, you can run
+   ``lxc-create -t ubuntu -h``.
+
+Start Container
+----------------
+
+To start the container, run::
+
+  sudo lxc-start -n devstack
+
+A moment later you should be presented with the login prompt for your container.
+You can login using the username ``ubuntu`` and password ``ubuntu``.
+
+You can also ssh into your container. On your host, run
+``sudo lxc-info -n devstack`` to get the IP address (e.g. 
+``ssh ubuntu@$(sudo lxc-info -n p2 | awk '/IP/ { print $2 }')``).
+
+Run Devstack
+-------------
+
+You should now be logged into your container and almost ready to run devstack.
+The commands in this section should all be run inside your container.
+
+.. Tip:: You can greatly reduce the runtime of your initial devstack setup by
+   ensuring you have your apt sources.list configured to use a fast mirror.
+   Check and update ``/etc/apt/sources.list`` if necessary and then run 
+   ``apt-get update``.
+
+#. Download DevStack
+
+   ::
+
+       git clone https://git.openstack.org/openstack-dev/devstack
+
+#. Configure
+
+   Refer to :ref:`minimal-configuration` if you wish to configure the behaviour
+   of devstack.
+
+#. Start the install
+
+   ::
+
+       cd devstack
+       ./stack.sh
+
+Cleanup
+-------
+
+To stop the container::
+
+  lxc-stop -n devstack
+
+To delete the container::
+
+  lxc-destroy -n devstack
+
+Limitations
+============
+
+Not all OpenStack features may function correctly or at all when ran from within
+a container.
+
+Cinder
+-------
+
+Unable to create LVM backed volume
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+  In our configuration, we have not whitelisted access to device-mapper or LVM
+  devices. Doing so will permit your container to have access and control of LVM
+  on the host system. To enable, add the following to your
+  ``devstack-lxc.conf`` before running ``lxc-create``::
+
+    lxc.cgroup.devices.allow = c 10:236 rwm
+    lxc.cgroup.devices.allow = b 252:* rwm
+
+  Additionally you'll need to set ``udev_rules = 0`` in the ``activation``
+  section of ``/etc/lvm/lvm.conf`` unless you mount devtmpfs in your container.
+
+Unable to attach volume to instance
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+  It is not possible to attach cinder volumes to nova instances due to parts of
+  the Linux iSCSI implementation not being network namespace aware. This can be
+  worked around by using network pass-through instead of a separate network
+  namespace but such a setup significantly reduces the isolation of the
+  container (e.g. a ``halt`` command issued in the container will cause the host
+  system to shutdown).

doc/source/index.rst

@@ -76,6 +76,7 @@ Walk through various setups used by stackers
 
    guides/single-vm
    guides/single-machine
+   guides/lxc
    guides/multinode-lab
    guides/neutron
    guides/devstack-with-nested-kvm
@@ -96,6 +97,13 @@ Run :doc:`OpenStack on dedicated hardware <guides/single-machine>`  This can inc
 server-class machine or a laptop at home.
 :doc:`[Read] <guides/single-machine>`
 
+All-In-One LXC Container
+-------------------------
+
+Run :doc:`OpenStack in a LXC container <guides/lxc>`. Beneficial for intermediate
+and advanced users. The VMs launched in this cloud will be fully accelerated but
+not all OpenStack features are supported. :doc:`[Read] <guides/lxc>`
+
 Multi-Node Lab
 --------------