Pin zun jobs to Docker 20

Related-Bug: #2007142

Change-Id: I9ce2a9ce5413e77625201f3986967e31a679ad9c

doc/source/reference/compute/zun-guide.rst

@@ -23,6 +23,16 @@ following variables:
    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.*"
+
 Docker reconfiguration requires rebootstrapping before deploy.
 Make sure you understand the consequences of restarting Docker.
 Please see :ref:`rebootstrapping` for details.

tests/templates/globals-default.j2

@@ -78,6 +78,9 @@ enable_cinder: "yes"
 # lvm backup driver for cinder-backup does not exist
 enable_cinder_backup: "no"
 enable_cinder_backend_lvm: "yes"
+# pin Docker to 20 - https://bugs.launchpad.net/zun/+bug/2007142
+docker_apt_package_pin: "5:20.*"
+docker_yum_package_pin: "20.*"
 {% endif %}
 
 {% if scenario == "swift" %}

zuul.d/base.yaml

@@ -103,6 +103,7 @@
       - ^tests/test-core-openstack.sh
       - ^tests/test-zun.sh
       - ^tests/test-dashboard.sh
+      - ^tests/templates/globals-default\.j2$
     vars:
       scenario: zun