Allow container creation on ZFS backing storage

Add a conditional task to create the base container on ZFS backing
storage.

Change-Id: Id6871f37aa2e7729d42acc0233ccd057706d8d24

tasks/lxc_cache_create.yml

@@ -107,3 +107,19 @@
     - lxc_container_backing_store == 'lvm'
     - lxc_container_backing_method is defined
     - lxc_container_backing_method == 'copy-on-write'
+
+- name: Create base container to use for ZFS-backed containers
+  lxc_container:
+    name: "{{ lxc_container_base_name }}"
+    template: "download"
+    state: stopped
+    backing_store: "zfs"
+    zfs_root: "{{ lxc_container_zfs_root_name }}"
+    template_options: "{{ lxc_cache_download_template_options }}"
+  register: cache_download
+  retries: 3
+  delay: 10
+  until: cache_download|success
+  when:
+    - lxc_container_backing_store is defined
+    - lxc_container_backing_store == 'zfs'