Pass UserKnownHostsFile and deploy ssh key

Mistral failed to run the ansible-playbook because it was unable to
create a known hosts file. This change passes UserKnownHostsFile as
an extra SSH argument to resolve that.

Also deploy and authorize an ssh key, which Ansible can then use for
connecting to the overcloud.

Co-Authored-By: Jiri Stransky <jistr@redhat.com>
Change-Id: I0392726372934a0530e692dbc77a205ce0919ff1

workbooks/ceph-ansible.yaml

@@ -11,6 +11,9 @@ workflows:
       - ceph_ansible_extra_vars: {}
       - ceph_ansible_playbook: /usr/share/ceph-ansible/site-docker.yml.sample
     tasks:
+      deploy_ssh_key:
+        workflow: tripleo.validations.v1.copy_ssh_key
+        on-success: get_private_key
       get_private_key:
         action: tripleo.validations.get_privkey
         publish:
@@ -67,7 +70,8 @@ workflows:
           verbosity: <% $.ansible_playbook_verbosity %>
           forks: <% $.fork_count %>
           ssh_private_key: <% $.private_key %>
-          ssh_extra_args: '-o StrictHostKeyChecking=no'
+          ssh_common_args: '-o StrictHostKeyChecking=no'
+          ssh_extra_args: '-o UserKnownHostsFile=/dev/null'
           skip_tags: 'package-install,with_pkg'
           extra_env_variables:
             ANSIBLE_CONFIG: /usr/share/ceph-ansible/ansible.cfg