Support containerized undercloud upgrade

Add a boolean and a condition to support upgrades to a containerized
undercloud.
In the future, we'll have one command but we're not there yet (until
it's default).

Change-Id: I726f63aeb1499709cd2c5da206943c7246dc54d3

README.md

@@ -47,6 +47,10 @@ Only create update scripts without running them
 
 Run undercloud upgrade
 
+    containerized_undercloud_upgrade: false
+
+Run containerized undercloud upgrade
+
     overcloud_upgrade: false
 
 Run overcloud upgrade

defaults/main.yml

@@ -13,6 +13,7 @@ overcloud_stack_name: "overcloud"
 upgrade_noop: false
 update_noop: false
 undercloud_upgrade: false
+containerized_undercloud_upgrade: false
 overcloud_upgrade: false
 undercloud_update: false
 overcloud_update: false

templates/undercloud_upgrade.sh.j2

@@ -4,4 +4,9 @@
 set -euo pipefail
 
 sudo yum update -y python-tripleoclient
+{% if containerized_undercloud_upgrade|bool %}
+# Add --use-heat until it becomes the default, hopefully in Rocky.
+openstack undercloud upgrade --use-heat &> undercloud_{{ log_prefix }}.log
+{% else %}
 openstack undercloud upgrade &> undercloud_{{ log_prefix }}.log
+{% endif %}