=======================
Zun - Container service
=======================

"Zun is an OpenStack Container service. It aims to provide an
OpenStack API for provisioning and managing containerized
workload on OpenStack."
For more details about Zun, see `OpenStack Zun Documentation
<https://docs.openstack.org/zun/latest/>`__.

.. warning::

   Zun is currently NOT SUPPORTED for this version of Kolla-Ansible.

   Since work on repairing compatibility is expected to start development
   during the 2024.1 release cycle, backports will be considered to the
   stable series to bridge the migration path.

   While the service containers and ansible roles still remain, a working
   installation is currently not possible in CI, and therefore is not
   supported.

Preparation and Deployment
--------------------------

By default Zun and its dependencies are disabled.
In order to enable Zun, you need to edit globals.yml and set the
following variables:

.. code-block:: yaml

   enable_zun: "yes"
   enable_kuryr: "yes"
   enable_etcd: "yes"
   docker_configure_for_zun: "yes"
   containerd_configure_for_zun: "yes"

Currently Kuryr does not support Docker 23 and later due to
dropped --cluster-store option (bug
`bug <https://bugs.launchpad.net/zun/+bug/2007142>`__).You need
to cap docker by setting the following variables in globals.yml.

.. code-block:: yaml

   docker_apt_package_pin: "5:20.*"
   docker_yum_package_pin: "20.*"

Debian Bookworm is not recommended as a host OS for Zun.
It does not support a version of Docker with the deprecated option.
Compatibility with Zun is not tested in CI.

Docker reconfiguration requires rebootstrapping before deploy.
Make sure you understand the consequences of restarting Docker.
Please see :ref:`rebootstrapping` for details.
If it's initial deploy, then there is nothing to worry about
because it's initial bootstrapping as well and there are no
running services to affect.

.. code-block:: console

   $ kolla-ansible bootstrap-servers

Finally deploy:

.. code-block:: console

   $ kolla-ansible deploy

Verification
------------

#. Generate the credentials file:

   .. code-block:: console

      $ kolla-ansible post-deploy

#. Source credentials file:

   .. code-block:: console

      $ . /etc/kolla/admin-openrc.sh

#. Download and create a glance container image:

   .. code-block:: console

      $ docker pull cirros
      $ docker save cirros | openstack image create cirros --public \
        --container-format docker --disk-format raw

#. Create zun container:

   .. code-block:: console

      $ zun create --name test --net network=demo-net cirros ping -c4 8.8.8.8

   .. note::

      Kuryr does not support networks with DHCP enabled, disable DHCP in the
      subnet used for zun containers.

      .. code-block:: console

         $ openstack subnet set --no-dhcp <subnet>

#. Verify container is created:

   .. code-block:: console

      $ zun list

      +--------------------------------------+------+---------------+---------+------------+------------+-------+
      | uuid                                 | name | image         | status  | task_state | addresses  | ports |
      +--------------------------------------+------+---------------+---------+------------+------------+-------+
      | 3719a73e-5f86-47e1-bc5f-f4074fc749f2 | test | cirros        | Created | None       | 172.17.0.3 | []    |
      +--------------------------------------+------+---------------+---------+------------+------------+-------+

#. Start container:

   .. code-block:: console

      $ zun start test
      Request to start container test has been accepted.

#. Verify container:

   .. code-block:: console

      $ zun logs test
      PING 8.8.8.8 (8.8.8.8): 56 data bytes
      64 bytes from 8.8.8.8: seq=0 ttl=45 time=96.396 ms
      64 bytes from 8.8.8.8: seq=1 ttl=45 time=96.504 ms
      64 bytes from 8.8.8.8: seq=2 ttl=45 time=96.721 ms
      64 bytes from 8.8.8.8: seq=3 ttl=45 time=95.884 ms

      --- 8.8.8.8 ping statistics ---
      4 packets transmitted, 4 packets received, 0% packet loss
      round-trip min/avg/max = 95.884/96.376/96.721 ms

For more information about how zun works, see
`zun, OpenStack Container service <https://docs.openstack.org/zun/latest/>`__.