Use ANSIBLE_PRIVATE_KEY_FILE when adding hosts to inventory

The cli command openstack overcloud admin authorize allows the user to
specify any ssh key with --overcloud-ssh-key. That key ends up getting
set as the environment variable ANSIBLE_PRIVATE_KEY_FILE.

When cli-enable-ssh-admin.yaml runs and adds the overcloud nodes to the
inventory, it needs to use the key from ANSIBLE_PRIVATE_KEY_FILE, if one
was specified.

This patch also removes strategy:free from the play to apply the
tripleo_create_admin role as it is not compatible with any_errors_fatal,
which is desired. Using the free strategy also results in more difficult
to parse output in that the task results aren't grouped per task.

Change-Id: Ib29b2050bf02561a9cd3d96716fc6fa3c4ea3994

tripleo_ansible/playbooks/cli-enable-ssh-admin.yaml

@@ -188,7 +188,7 @@
         user_public_key: "{{ user_public_key }}"
         user_private_key: "{{ user_private_key }}"
         user_private_key_file: "{{ user_private_key_file }}"
-        ansible_ssh_private_key_file: "{{ ansible_home }}/.ssh/id_rsa"
+        ansible_ssh_private_key_file: "{{ lookup('env', 'ANSIBLE_PRIVATE_KEY_FILE') | default(ansible_home ~ '/.ssh/id_rsa') }}"
       changed_when: false
       loop: '{{ set_ssh_servers | difference(((BlacklistedIpAddresses | length) < 1) | ternary([], BlacklistedIpAddresses)) }}'
 
@@ -198,7 +198,6 @@
   user: "{{ ssh_user | default('heat-admin') }}"
   become: true
   any_errors_fatal: true
-  strategy: free
   roles:
     - role: tripleo_create_admin
       tripleo_admin_user: tripleo-admin