watcher/doc/source/contributor/devstack.rst

..
      Except where otherwise noted, this document is licensed under Creative
      Commons Attribution 3.0 License.  You can view the license at:

          https://creativecommons.org/licenses/by/3.0/

=============================================
Set up a development environment via DevStack
=============================================

Watcher is currently able to optimize compute resources - specifically Nova
compute hosts - via operations such as live migrations. In order for you to
fully be able to exercise what Watcher can do, it is necessary to have a
multinode environment to use.

You can set up the Watcher services quickly and easily using a Watcher
DevStack plugin. See `PluginModelDocs`_ for information on DevStack's plugin
model. To enable the Watcher plugin with DevStack, add the following to the
``[[local|localrc]]`` section of your controller's ``local.conf`` to enable the
Watcher plugin::

    enable_plugin watcher https://opendev.org/openstack/watcher

For more detailed instructions, see `Detailed DevStack Instructions`_. Check
out the `DevStack documentation`_ for more information regarding DevStack.

.. _PluginModelDocs: https://docs.openstack.org/devstack/latest/plugins.html
.. _DevStack documentation: https://docs.openstack.org/devstack/latest

Quick Devstack Instructions with Datasources
============================================

Watcher requires a datasource to collect metrics from compute nodes and
instances in order to execute most strategies. To enable this a
``[[local|localrc]]`` to setup DevStack for some of the supported datasources
is provided. These examples specify the minimal configuration parameters to
get both Watcher and the datasource working but can be expanded is desired.

Gnocchi
-------

With the Gnocchi datasource most of the metrics for compute nodes and
instances will work with the provided configuration but metrics that
require Ironic such as ``host_airflow and`` ``host_power`` will still be
unavailable as well as ``instance_l3_cpu_cache``

.. code-block:: ini

   [[local|localrc]]

   enable_plugin watcher https://opendev.org/openstack/watcher
   enable_plugin watcher-dashboard https://opendev.org/openstack/watcher-dashboard
   enable_plugin ceilometer https://opendev.org/openstack/ceilometer.git
   enable_plugin aodh https://opendev.org/openstack/aodh
   enable_plugin panko https://opendev.org/openstack/panko

   CEILOMETER_BACKEND=gnocchi
   [[post-config|$NOVA_CONF]]
   [DEFAULT]
   compute_monitors=cpu.virt_driver

Detailed DevStack Instructions
==============================

#.  Obtain N (where N >= 1) servers (virtual machines preferred for DevStack).
    One of these servers will be the controller node while the others will be
    compute nodes. N is preferably >= 3 so that you have at least 2 compute
    nodes, but in order to stand up the Watcher services only 1 server is
    needed (i.e., no computes are needed if you want to just experiment with
    the Watcher services). These servers can be VMs running on your local
    machine via VirtualBox if you prefer. DevStack currently recommends that
    you use Ubuntu 16.04 LTS. The servers should also have connections to the
    same network such that they are all able to communicate with one another.

#. For each server, clone the DevStack repository and create the stack user

   .. code-block:: bash

        sudo apt-get update
        sudo apt-get install git
        git clone https://opendev.org/openstack/devstack.git
        sudo ./devstack/tools/create-stack-user.sh

   Now you have a stack user that is used to run the DevStack processes. You
   may want to give your stack user a password to allow SSH via a password

   .. code-block:: bash

        sudo passwd stack

#. Switch to the stack user and clone the DevStack repo again

   .. code-block:: bash

        sudo su stack
        cd ~
        git clone https://opendev.org/openstack/devstack.git

#. For each compute node, copy the provided `local.conf.compute`_ example file
   to the compute node's system at ~/devstack/local.conf. Make sure the
   HOST_IP and SERVICE_HOST values are changed appropriately - i.e., HOST_IP
   is set to the IP address of the compute node and SERVICE_HOST is set to the
   IP address of the controller node.

   If you need specific metrics collected (or want to use something other
   than Ceilometer), be sure to configure it. For example, in the
   `local.conf.compute`_ example file, the appropriate ceilometer plugins and
   services are enabled and disabled. If you were using something other than
   Ceilometer, then you would likely want to configure it likewise. The
   example file also sets the compute monitors nova configuration option to
   use the CPU virt driver. If you needed other metrics, it may be necessary
   to configure similar configuration options for the projects providing those
   metrics.

#. For the controller node, copy the provided `local.conf.controller`_ example
   file to the controller node's system at ~/devstack/local.conf. Make sure
   the HOST_IP value is changed appropriately - i.e., HOST_IP is set to the IP
   address of the controller node.

   .. NOTE::
        if you want to use another Watcher git repository (such as a local
        one), then change the enable plugin line

   .. code-block:: bash

        enable_plugin watcher <your_local_git_repo> [optional_branch]


   If you do this, then the Watcher DevStack plugin will try to pull the
   python-watcherclient repo from ``<your_local_git_repo>/../``, so either make
   sure that is also available or specify WATCHERCLIENT_REPO in the ``local.conf``
   file.

   .. NOTE::
        if you want to use a specific branch, specify WATCHER_BRANCH in the
        local.conf file. By default it will use the master branch.

   .. Note::
        watcher-api will default run under apache/httpd, set the variable
        WATCHER_USE_MOD_WSGI=FALSE if you do not wish to run under apache/httpd.
        For development environment it is suggested to set WATHCER_USE_MOD_WSGI
        to FALSE. For Production environment it is suggested to keep it at the
        default TRUE value.

#. Start stacking from the controller node::

       ./devstack/stack.sh

#. Start stacking on each of the compute nodes using the same command.

   .. seealso::
        Configure the environment for live migration via NFS. See the
        `Multi-Node DevStack Environment`_ section for more details.

.. _local.conf.controller: https://github.com/openstack/watcher/tree/master/devstack/local.conf.controller
.. _local.conf.compute: https://github.com/openstack/watcher/tree/master/devstack/local.conf.compute

Multi-Node DevStack Environment
===============================

Since deploying Watcher with only a single compute node is not very useful, a
few tips are given here for enabling a multi-node environment with live
migration.

.. NOTE::

    Nova supports live migration with local block storage so by default NFS
    is not required and is considered an advance configuration.
    The minimum requirements for live migration are:

        - all hostnames are resolvable on each host
        - all hosts have a passwordless ssh key that is trusted by the other hosts
        - all hosts have a known_hosts file that lists each hosts

    If these requirements are met live migration will be possible.
    Shared storage such as ceph, booting form cinder volume or nfs are recommend
    when testing evacuate if you want to preserve vm data.

Setting up SSH keys between compute nodes to enable live migration
------------------------------------------------------------------

In order for live migration to work, SSH keys need to be exchanged between
each compute node:

1. The SOURCE root user's public RSA key (likely in /root/.ssh/id_rsa.pub)
   needs to be in the DESTINATION stack user's authorized_keys file
   (~stack/.ssh/authorized_keys). This can be accomplished by manually
   copying the contents from the file on the SOURCE to the DESTINATION. If
   you have a password configured for the stack user, then you can use the
   following command to accomplish the same thing::

        ssh-copy-id -i /root/.ssh/id_rsa.pub stack@DESTINATION

2. The DESTINATION host's public ECDSA key (/etc/ssh/ssh_host_ecdsa_key.pub)
   needs to be in the SOURCE root user's known_hosts file
   (/root/.ssh/known_hosts). This can be accomplished by running the
   following on the SOURCE machine (hostname must be used)::

        ssh-keyscan -H DEST_HOSTNAME | sudo tee -a /root/.ssh/known_hosts

In essence, this means that every compute node's root user's public RSA key
must exist in every other compute node's stack user's authorized_keys file and
every compute node's public ECDSA key needs to be in every other compute
node's root user's known_hosts file.

Configuring NFS Server (ADVANCED)
---------------------------------

If you would like to use live migration for shared storage, then the controller
can serve as the NFS server if needed

.. code-block:: bash

    sudo apt-get install nfs-kernel-server
    sudo mkdir -p /nfs/instances
    sudo chown stack:stack /nfs/instances

Add an entry to ``/etc/exports`` with the appropriate gateway and netmask
information


.. code-block:: bash

    /nfs/instances <gateway>/<netmask>(rw,fsid=0,insecure,no_subtree_check,async,no_root_squash)

Export the NFS directories

.. code-block:: bash

    sudo exportfs -ra

Make sure the NFS server is running

.. code-block:: bash

    sudo service nfs-kernel-server status

If the server is not running, then start it

.. code-block:: bash

    sudo service nfs-kernel-server start

Configuring NFS on Compute Node (ADVANCED)
------------------------------------------

Each compute node needs to use the NFS server to hold the instance data

.. code-block:: bash

    sudo apt-get install rpcbind nfs-common
    mkdir -p /opt/stack/data/instances
    sudo mount <nfs-server-ip>:/nfs/instances /opt/stack/data/instances

If you would like to have the NFS directory automatically mounted on reboot,
then add the following to ``/etc/fstab``

.. code-block:: bash

    <nfs-server-ip>:/nfs/instances /opt/stack/data/instances nfs auto 0 0

Configuring libvirt to listen on tcp (ADVANCED)
-----------------------------------------------

.. NOTE::

    By default nova will use ssh as a transport for live migration
    if you have a low bandwidth connection you can use tcp instead
    however this is generally not recommended.


Edit ``/etc/libvirt/libvirtd.conf`` to make sure the following values are set

.. code-block:: ini

    listen_tls = 0
    listen_tcp = 1
    auth_tcp = "none"

Edit ``/etc/default/libvirt-bin``

.. code-block:: ini

    libvirtd_opts="-d -l"

Restart the libvirt service

.. code-block:: bash

    sudo service libvirt-bin restart

VNC server configuration
------------------------

The VNC server listening parameter needs to be set to any address so
that the server can accept connections from all of the compute nodes.

On both the controller and compute node, in ``/etc/nova/nova.conf``

.. code-block:: ini

    [vnc]
    server_listen = "0.0.0.0"

Alternatively, in devstack's ``local.conf``:

.. code-block:: bash

    VNCSERVER_LISTEN="0.0.0.0"


Environment final checkup
-------------------------

If you are willing to make sure everything is in order in your DevStack
environment, you can run the Watcher Tempest tests which will validate its API
but also that you can perform the typical Watcher workflows. To do so, have a
look at the :ref:`Tempest tests <tempest_tests>` section which will explain to
you how to run them.