Freeze libvirt image with date

This starts an alternative approach to the use of Zuul's date time,
whose fact availability is inconsistent across check/gates/promote
pipeline.

This implements an alternative approach for testing in the promote
pipeline.

Change-Id: Ib41797cabbb226ee35daab9f886fa0fc38120c32

zuul.d/base.yaml

@@ -56,6 +56,11 @@
     name: openstack-helm-images-build
     parent: build-docker-image
     abstract: true
+    # Minimum version required is 2.8.
+    # When default in zuul moves to 2.8, remove
+    # this line.
+    # See also: https://zuul-ci.org/docs/zuul/user/config.html#attr-job.ansible-version
+    ansible-version: 2.8
     description: |
       This job is building a docker image for
       OpenStack-Helm usage.
@@ -76,6 +81,7 @@
     name: openstack-helm-images-upload
     parent: upload-docker-image
     abstract: true
+    ansible-version: 2.8
     secrets:
       name: docker_credentials
       secret: openstack-helm-dockerhub
@@ -86,6 +92,7 @@
     name: openstack-helm-images-promote
     parent: promote-docker-image
     abstract: true
+    ansible-version: 2.8
     secrets:
       name: docker_credentials
       secret: openstack-helm-dockerhub

zuul.d/libvirt.yaml

@@ -32,17 +32,20 @@
     parent: openstack-helm-images-build
     description: Build libvirt images
     vars: &libvirt_vars
+      currentdate: "{{ now(utc=True,fmt='%Y%m%d') }}"
       docker_images:
         - context: libvirt
           repository: openstackhelm/libvirt
           tags:
             - latest-opensuse_15
+            - "opensuse_15-{{ currentdate }}"
           dockerfile: Dockerfile.suse_15
         - context: libvirt
           repository: openstackhelm/libvirt
           dockerfile: Dockerfile.ubuntu_xenial
           tags:
             - latest-ubuntu_xenial
+            - "ubuntu_xenial-{{ currentdate }}"
     files: &libvirt_files
       - libvirt/.*
       - zuul.d/libvirt.yaml