Zun: add Cinder (volume) iSCSI support

This makes iSCSI with Zun and Cinder work out-of-the-box.
(LVM included)

Change-Id: I2c4aa666ff9f952e32c450347d31ddbf2e58209e
Related-bug: #1797448
Closes-bug: #1848933

ansible/roles/zun/defaults/main.yml

@@ -95,6 +95,8 @@ zun_compute_default_volumes:
   - "/run:/run:shared"
   - "/usr/lib/docker:/usr/lib/docker"
   - "/var/lib/docker:/var/lib/docker"
+  - "/lib/modules:/lib/modules:ro"
+  - "{% if enable_iscsid | bool %}iscsi_info:/etc/iscsi{% endif %}"
 
 zun_extra_volumes: "{{ default_extra_volumes }}"
 zun_api_extra_volumes: "{{ zun_extra_volumes }}"

releasenotes/notes/zun-iscsi-7ca24c2c4eb9d5a5.yaml

+---
+features:
+  - |
+    Adds support for iSCSI-based (including LVM) Cinder volumes
+    to Zun deployment.