Switch the undercloud to deploy Podman by default starting from Stein

Starting from Stein, we want the Undercloud to be deploying Podman
containers instead of Docker containers.
This patch switches container_cli to be 'podman', and make sure we only
configure this new parameter in Stein and beyond.
Also run the container CLI with sudo, it's required to Podman on CentOS7.

blueprint podman-support
Change-Id: I21662de8ac0101a25c2b73a4650bb4af0f5df89a

roles/overcloud-prep-images/templates/overcloud-prep-images.sh.j2

@@ -222,8 +222,8 @@ sudo kill $pidof_tcpdump
 
 {% endif %}
 
-{% if release not in ['newton', 'ocata', 'pike', 'queens'] %}
-container_cli="{{ undercloud_container_cli | default('docker') }}"
+{% if release not in ['newton', 'ocata', 'pike', 'queens', 'rocky'] %}
+container_cli="{{ undercloud_container_cli | default('podman') }}"
 cont=$(sudo $container_cli ps | grep executor | awk {'print $1'})
 sudo $container_cli exec --user root $cont bash -c "easy_install pip && pip install ara"
 # check it

roles/undercloud-deploy/README.md

@@ -97,7 +97,7 @@ https://docs.openstack.org/tripleo-quickstart/latest/accessing-libvirt.html
 - `undercloud_roles_data`: <null> -- A custom t-h-t roles file. Consumed from ``undercloud_templates_path``
   or an alternative location as well.
 - `undercloud_selinux_enabled`: <'true'> -- Enabled for RHEL by default, Disabled for CentOS by default
-- `undercloud_container_cli`: <'docker'> -- Container CLI to use for the Undercloud deployment. Default to 'docker'.
+- `undercloud_container_cli`: <'podman'> -- Container CLI to use for the Undercloud deployment. Default to 'podman'.
 
 Role Network Variables
 ----------------------

roles/undercloud-deploy/defaults/main.yml

@@ -91,7 +91,12 @@ undercloud_selinux_enabled: >-
    true
    {%- endif -%}
 
-undercloud_container_cli: docker
+undercloud_container_cli: >-
+   {% if release not in ['newton', 'ocata', 'pike', 'queens', 'rocky'] -%}
+   podman
+   {% else %}
+   docker
+   {% endif %}
 
 # Define a custom t-h-t installation for UC
 undercloud_custom_tht_script: custom-tht-script.sh.j2

roles/undercloud-deploy/templates/containers-prepare-parameter.yaml.j2

@@ -11,6 +11,7 @@ parameter_defaults:
     modify_vars:
       tasks_from: yum_update.yml
       yum_repos_dir_path: /etc/yum.repos.d
+      container_build_tool: buildah
       update_repo: "{{ update_containers_repo }}"
 {% endif %}
     set:

roles/undercloud-deploy/templates/undercloud.conf.j2

@@ -211,7 +211,7 @@ inspection_runbench = {{undercloud_inspection_runbench}}
 # services. (boolean value)
 undercloud_debug = {{undercloud_undercloud_debug}}
 
-{% if containerized_undercloud|bool %}
+{% if containerized_undercloud|bool and release != 'rocky' %}
 # Container CLI used for deployment;
 # Can be docker or podman. (string value)
 container_cli = {{undercloud_container_cli}}