If /var/lib/libvirt/qemu/save exists, move it to nova_libvirt_save_path

In https://review.openstack.org/320624 the qemu save directory was set
to be a link into the same directory where nova instances are kept in
order to ensure that temporary files created in snapshots are stored
in a location which is likely on shared storage or has plenty of space.

The patch did not actually create the link if a folder existed there
already, so this patch implements a move of the folder and a link to
replace it.

Closes-Bug: #1585325
Change-Id: I5224ac72b14ad027410f5d5c14d20870dd37b5cb

tasks/nova_compute_kvm_install.yml

@@ -13,28 +13,34 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-- name: Check if qemu save directory is a directory
+- name: Check the state of the default qemu save directory
   stat:
     path: "/var/lib/libvirt/qemu/save"
-  register: qemu_savedir_stat
+  register: _qemu_save_dir
 
-- name: Check if qemu save directory is empty
+- name: Check if the qemu save directory is empty
   shell: 'ls -1A /var/lib/libvirt/qemu/save'
-  register: qemu_savedir_empty
+  register: _qemu_save_dir_contents
+
+- name: Move the existing save directory to nova_libvirt_save_path
+  command: "mv /var/lib/libvirt/qemu/save {{ nova_libvirt_save_path }}"
+  when:
+    - _qemu_save_dir.stat.isdir is defined
+    - _qemu_save_dir.stat.isdir | bool
+    - _qemu_save_dir_contents.stdout_lines | length == 0
+
+- name: Create the new save directory
+  file:
+    path: "{{ nova_libvirt_save_path }}"
+    state: directory
 
-# We force the link creation if our tests passed, this removes the directory as
-# well
 - name: Symlink qemu save dir to nova_libvirt_save_path
   file:
-    path: "/var/lib/libvirt/qemu/save"
+    src: "{{ nova_libvirt_save_path }}"
+    dest: "/var/lib/libvirt/qemu/save"
     state: link
     owner: "{{ nova_qemu_user }}"
     group: "{{ nova_qemu_group }}"
-    src: "{{ nova_libvirt_save_path }}"
-    force: True
-  when:
-    - qemu_savedir_stat.stat.isdir
-    - qemu_savedir_empty.stdout_lines | length == 0
 
 - name: Install pip packages
   pip: