Fallback to public IPv4 when there is no priv. IP

Similarly to I139272746129213994f298a4a9178b4441d439af and
I32fb17bae98f13f735da4d5b9a6a01e948f21678, fallback to
public IPv4, when populating the nodepool files important to be
set up for the pre-deployment zuul stages.

In particular, this allows the multi-node CI reproducer with
static/libvirt nodepool provider to always have the overcloud group
defined, even if it consists of subnodes running with a single IP.

Change-Id: I4eabef8b1d7a20d8474c70091960c8001c3a746a
Signed-off-by: Bogdan Dobrelya <bdobreli@redhat.com>

playbooks/openstack-zuul-jobs/legacy/pre.yaml

@@ -1,6 +1,18 @@
+- hosts: all
+  gather_facts: no
+  tasks:
+    - name: Set IP addresses for the nodes missing private IPs
+      set_fact:
+        nodepool_ip: "{{ nodepool.public_ipv4 }}"
+      when: not (nodepool.private_ipv4 | ipv4)
+
+    - name: Set IP addresses for the nodes without private IPs (a fallback)
+      set_fact:
+        nodepool_ip: "{{ nodepool.private_ipv4 | default(nodepool.public_ipv4) }}"
+      when: nodepool_ip is not defined
+
 - hosts: all
   tasks:
-
     - name: Create nodepool directory
       file:
         path: /etc/nodepool
@@ -26,7 +38,7 @@
     - name: Populate nodepool sub_nodes_private file
       lineinfile:
         path: /etc/nodepool/sub_nodes_private
-        line: "{{ hostvars[item]['nodepool']['private_ipv4'] }}"
+        line: "{{ hostvars[item]['nodepool_ip'] }}"
         insertafter: EOF
       with_items: "{{ groups['subnodes'] }}"
       when: groups['subnodes'] is defined
@@ -34,13 +46,13 @@
     - name: Create nodepool primary file
       copy:
         dest: /etc/nodepool/primary_node_private
-        content: "{{ hostvars['primary']['nodepool']['private_ipv4'] }}"
+        content: "{{ hostvars['primary']['nodepool_ip'] }}"
       when: hostvars['primary'] is defined
 
     - name: Create nodepool node_private for this node
       copy:
         dest: /etc/nodepool/node_private
-        content: "{{ nodepool.private_ipv4 }}"
+        content: "{{ nodepool_ip }}"
 
     - name: Copy ssh keys to nodepool directory
       command: "cp .ssh/{{ item }} /etc/nodepool/{{ item }}"