Make provision/remote role safe to include statically

Currently including the provision/remote role without intending to
actually use it will break if the {{ virt_host_key }}.pub file does
not exist.

Ideally, we would be able to include it dynamically so that the
tasks are not evaluated at compile time, but instead only if they
are run. This would require a pretty large refactor though, because
playbooks can not be included dynamically.

Instead, we can make sure to have a default for the lookup so that
it will not fail to evaluate. The task would still fail to run if
the lookup falls back to the default, so we wont hide issues with
the key not existing with this change.

Change-Id: I347de079ada7c7b82f2f7affafa97f95c8029a3f

roles/libvirt/setup/undercloud/tasks/main.yml

@@ -102,9 +102,7 @@
   - name: Add virt power key to root authorized keys if using qemu:///system
     authorized_key:
       user: root
-      key: "{{ item }}"
-    with_file:
-      - "{{ virt_power_key }}.pub"
+      key: "{{ lookup('file', virt_power_key|quote + '.pub')|default('') }}"
     when: libvirt_uri == "qemu:///system"
 
   # Copy the public key to `$HOME/.ssh/authorized_keys` for the `root`

roles/libvirt/setup/user/tasks/main.yml

@@ -35,15 +35,11 @@
 - name: Read virt_power private key
   no_log: True
   set_fact:
-    virt_power_key_pvt: "{{ item }}"
-  with_file:
-    - "{{ virt_power_key }}"
+    virt_power_key_pvt: "{{ lookup('file', virt_power_key)|default('') }}"
 
 - name: add virt_power_key to remote authorized_keys
   authorized_key:
     user: "{{ ansible_user_id }}"
-    key: "{{ item }}"
+    key: "{{ lookup('file', virt_power_key|quote + '.pub')|default('') }}"
     manage_dir: true
-  with_file:
-    - "{{ virt_power_key }}.pub"
 

roles/provision/remote/tasks/main.yml

@@ -57,9 +57,7 @@
 - name: Configure non-root user authorized_keys
   authorized_key:
     user: "{{ ssh_user }}"
-    key: "{{ item }}"
-  with_file:
-    - "{{ virt_host_key }}.pub"
+    key: "{{ lookup('file', virt_host_key|quote + '.pub')|default('') }}"
   become: true
 
 - name: Ensure polkit packages are installed