This file will write out the heat environment file
containers-prepare-parameter.yaml which will be used to do any
required image preparation during undercloud install.
The role parameter undercloud_container_images_file has been left as
an option for overriding, but is no longer required.
This change also switches the overcloud prepare to consume this file
via the command "openstack tripleo container image prepare"
It is expected that overcloud deploy will use the exact same
containers-prepare-parameter.yaml and the logic will be in place to
skip any unnecessary prepare actions. For this reason, the parameter
undercloud_docker_image_tag has been removed, and docker_image_tag is
used directly.
Since this file (and the variables used to build it) will be common to
undercloud and overcloud, there has been some refactoring to move
variable defaults to extras-common.
Change-Id: I290806b9296773688dfd02bc41f8baea28cf3d6a
Blueprint: container-prepare-workflow
b3794ff03a