Install and configure a compute node
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This section describes how to install and configure the Compute
service on a compute node. The service supports several
:term:`hypervisors <hypervisor>` to deploy :term:`instances <instance>`
or :term:`VMs <virtual machine (VM)>`. For simplicity, this configuration
uses the :term:`QEMU <Quick EMUlator (QEMU)>` hypervisor with the
:term:`KVM <kernel-based VM (KVM)>` extension
on compute nodes that support hardware acceleration for virtual machines.
On legacy hardware, this configuration uses the generic QEMU hypervisor.
You can follow these instructions with minor modifications to horizontally
scale your environment with additional compute nodes.

.. note::

   This section assumes that you are following the instructions in
   this guide step-by-step to configure the first compute node. If you
   want to configure additional compute nodes, prepare them in a similar
   fashion to the first compute node in the :ref:`example architectures
   <overview-example-architectures>` section. Each additional compute node
   requires a unique IP address.

Install and configure components
--------------------------------

.. include:: shared/note_configuration_vary_by_distribution.rst

.. only:: obs

   #. Install the packages:

      .. code-block:: console

         # zypper install openstack-nova-compute genisoimage kvm libvirt

.. only:: rdo

   #. Install the packages:

      .. code-block:: console

         # yum install openstack-nova-compute

.. only:: ubuntu or debian

   #. Install the packages:

      .. code-block:: console

         # apt-get install nova-compute

      .. only:: debian

         Respond to prompts for
         :doc:`database management <debconf/debconf-dbconfig-common>`,
         :doc:`Identity service credentials <debconf/debconf-keystone-authtoken>`,
         and :doc:`message broker credentials <debconf/debconf-rabbitmq>`. Make
         sure that you do not activate database management handling by debconf,
         as a compute node should not access the central database.

2. Edit the ``/etc/nova/nova.conf`` file and
   complete the following actions:

   .. only:: obs or rdo or ubuntu

      * In the ``[DEFAULT]`` and [oslo_messaging_rabbit]
        sections, configure ``RabbitMQ`` message queue access:

        .. code-block:: ini

           [DEFAULT]
           ...
           rpc_backend = rabbit

           [oslo_messaging_rabbit]
           ...
           rabbit_host = controller
           rabbit_userid = openstack
           rabbit_password = RABBIT_PASS

        Replace ``RABBIT_PASS`` with the password you chose for
        the ``openstack`` account in ``RabbitMQ``.

      * In the ``[DEFAULT]`` and ``[keystone_authtoken]`` sections,
        configure Identity service access:

        .. code-block:: ini

           [DEFAULT]
           ...
           auth_strategy = keystone

           [keystone_authtoken]
           ...
           auth_uri = http://controller:5000
           auth_url = http://controller:35357
           memcached_servers = controller:11211
           auth_type = password
           project_domain_name = default
           user_domain_name = default
           project_name = service
           username = nova
           password = NOVA_PASS

        Replace ``NOVA_PASS`` with the password you chose for the
        ``nova`` user in the Identity service.

        .. note::

           Comment out or remove any other options in the
           ``[keystone_authtoken]`` section.

   .. only:: debian

      * In the ``[DEFAULT]`` section, check that the ``my_ip`` option
        is correctly set (this value is handled by the config and postinst
        scripts of the ``nova-common`` package using debconf):

        .. code-block:: ini

           [DEFAULT]
           ...
           my_ip = MANAGEMENT_INTERFACE_IP_ADDRESS

        Replace ``MANAGEMENT_INTERFACE_IP_ADDRESS`` with the IP address
        of the management network interface on your compute node,
        typically 10.0.0.31 for the first node in the
        :ref:`example architecture <overview-example-architectures>`.

   .. only:: obs or rdo or ubuntu

      * In the ``[DEFAULT]`` section, configure the ``my_ip`` option:

        .. code-block:: ini

           [DEFAULT]
           ...
           my_ip = MANAGEMENT_INTERFACE_IP_ADDRESS

        Replace ``MANAGEMENT_INTERFACE_IP_ADDRESS`` with the IP address
        of the management network interface on your compute node,
        typically 10.0.0.31 for the first node in the
        :ref:`example architecture <overview-example-architectures>`.

   * In the ``[DEFAULT]`` section, enable support for the Networking service:

     .. code-block:: ini

        [DEFAULT]
        ...
        use_neutron = True
        firewall_driver = nova.virt.firewall.NoopFirewallDriver

     .. note::

        By default, Compute uses an internal firewall service. Since
        Networking includes a firewall service, you must disable the Compute
        firewall service by using the
        ``nova.virt.firewall.NoopFirewallDriver`` firewall driver.

   * In the ``[vnc]`` section, enable and configure remote console access:

     .. code-block:: ini

        [vnc]
        ...
        enabled = True
        vncserver_listen = 0.0.0.0
        vncserver_proxyclient_address = $my_ip
        novncproxy_base_url = http://controller:6080/vnc_auto.html

     The server component listens on all IP addresses and the proxy
     component only listens on the management interface IP address of
     the compute node. The base URL indicates the location where you
     can use a web browser to access remote consoles of instances
     on this compute node.

     .. note::

        If the web browser to access remote consoles resides on
        a host that cannot resolve the ``controller`` hostname,
        you must replace ``controller`` with the management
        interface IP address of the controller node.

   * In the ``[glance]`` section, configure the location of the
     Image service API:

     .. code-block:: ini

        [glance]
        ...
        api_servers = http://controller:9292

   .. only:: obs

      * In the ``[oslo_concurrency]`` section, configure the lock path:

        .. code-block:: ini

           [oslo_concurrency]
           ...
           lock_path = /var/run/nova

   .. only:: rdo or ubuntu

      * In the ``[oslo_concurrency]`` section, configure the lock path:

        .. code-block:: ini

           [oslo_concurrency]
           ...
           lock_path = /var/lib/nova/tmp

   .. only:: ubuntu

      .. todo:

         https://bugs.launchpad.net/ubuntu/+source/nova/+bug/1506667

      * Due to a packaging bug, remove the ``logdir`` option from the
        ``[DEFAULT]`` section.

.. only:: obs or debian

   3. Ensure the kernel module ``nbd`` is loaded.

      .. code-block:: console

         # modprobe nbd

   4. Ensure the module loads on every boot by adding ``nbd``
      to the ``/etc/modules-load.d/nbd.conf`` file.

Finalize installation
---------------------

#. Determine whether your compute node supports hardware acceleration
   for virtual machines:

   .. code-block:: console

      $ egrep -c '(vmx|svm)' /proc/cpuinfo

   If this command returns a value of ``one or greater``, your compute
   node supports hardware acceleration which typically requires no
   additional configuration.

   If this command returns a value of ``zero``, your compute node does
   not support hardware acceleration and you must configure ``libvirt``
   to use QEMU instead of KVM.

   .. only:: obs or rdo

      * Edit the ``[libvirt]`` section in the
        ``/etc/nova/nova.conf`` file as follows:

        .. code-block:: ini

           [libvirt]
           ...
           virt_type = qemu

   .. only:: ubuntu

      * Edit the ``[libvirt]`` section in the
        ``/etc/nova/nova-compute.conf`` file as follows:

        .. code-block:: ini

           [libvirt]
           ...
           virt_type = qemu

   .. only:: debian

      * Replace the ``nova-compute-kvm`` package with ``nova-compute-qemu``
        which automatically changes the ``/etc/nova/nova-compute.conf``
        file and installs the necessary dependencies:

        .. code-block:: console

           # apt-get install nova-compute-qemu

.. only:: obs or rdo

   2. Start the Compute service including its dependencies and configure
      them to start automatically when the system boots:

      .. code-block:: console

         # systemctl enable libvirtd.service openstack-nova-compute.service
         # systemctl start libvirtd.service openstack-nova-compute.service

.. only:: ubuntu or debian

   2. Restart the Compute service:

      .. code-block:: console

         # service nova-compute restart