Use slurp to collect the nova ssh keys

Extracting the ssh public key using cat and storing the result in a
fact has resulted in periodic failures in the collection of the key,
and thereafter the failure to appropriately place that key into the
authorised_keys file.

This patch changes the collection method to use the Ansible slurp
module which has been found to be more reliable.

Closes-Bug: #1531783
Change-Id: I26340a0c69064f84d9d87f19ce015ba44b6ffa8b

tasks/nova_compute_key_distribute.yml

@@ -16,7 +16,7 @@
 - name: Create authorized keys file from host vars
   authorized_key:
     user: "{{ nova_system_user_name }}"
-    key: "{{ hostvars[item]['nova_pubkey'] }}"
+    key: "{{ hostvars[item]['nova_pubkey'] | b64decode }}"
   with_items: groups['nova_compute']
   tags:
     - nova-key

tasks/nova_compute_key_populate.yml

@@ -25,8 +25,8 @@
     - nova-key-create
 
 - name: Get public key contents and store as var
-  command: |
-    cat {{ nova_system_home_folder }}/.ssh/id_rsa.pub
+  slurp:
+    src: "{{ nova_system_home_folder }}/.ssh/id_rsa.pub"
   register: nova_pub
   changed_when: false
   tags:
@@ -35,7 +35,7 @@
 
 - name: Register a fact for the nova pub key
   set_fact:
-     nova_pubkey: "{{ nova_pub.stdout }}"
+     nova_pubkey: "{{ nova_pub.content }}"
   tags:
     - nova-key
     - nova-key-create