Resolve btrfs backing store variable inconsistency

In Ica79472568799098ebf83c6cefc585f117975f37 some incorrect
variable names were used. This patch changes the variable
names to suit their purpose and ensures that they are used
consistently throughout the role.

Change-Id: If9e912641b5b6cb7791221b40dd4d56e215c2b98

defaults/main.yml

@@ -185,13 +185,15 @@ properties: {}
 # host.
 lxc_container_journal_link: true
 
-# Enable or Disable the BTRFS quota system for the "/var/lib/machines" mount
-# point. More information on the BTRFS quota system can be found here:
+# Enable or Disable the BTRFS quota system, which is used for the
+# "/var/lib/machines" mount point (for the machinectl backing store), or for
+# any containers with a btrfs backing store. More information on the BTRFS
+# quota system can be found here:
 #  * https://btrfs.wiki.kernel.org/index.php/Quota_support
-lxc_host_machine_quota_disabled: false
+lxc_host_btrfs_quota_disabled: false
 
-# Set the default qgroup limits used for file system quotas. The default is
-# "none". See the following documentation for more information:
+# Set the default qgroup limits used for btrfs file system quotas. The default
+# is "none". See the following documentation for more information:
 #  * https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-qgroup
-lxc_host_machine_qgroup_space_limit: none
-lxc_host_machine_qgroup_compression_limit: none
+lxc_host_btrfs_qgroup_space_limit: none
+lxc_host_btrfs_qgroup_compression_limit: none

releasenotes/notes/lxc-host-machine-vars-5d11b1f269167fd3.yaml

@@ -0,0 +1,15 @@
+---
+fixes:
+  - |
+    When using LXC containers with a copy-on-write back-end, the ``lxc_hosts``
+    role execution would fail due to undefined variables with the
+    ``nspawn_host_`` prefix. This issue has now been fixed.
+deprecations:
+  - |
+    The following variable name changes have been implemented in order to
+    better reflect their purpose.
+
+    * ``lxc_host_machine_quota_disabled`` -> ``lxc_host_btrfs_quota_disabled``
+    * ``lxc_host_machine_qgroup_space_limit`` -> ``lxc_host_btrfs_qgroup_space_limit``
+    * ``lxc_host_machine_qgroup_compression_limit`` -> ``lxc_host_btrfs_qgroup_compression_limit``
+

tasks/lxc_container_create_cow.yml

@@ -38,23 +38,23 @@
   when:
     - lxc_container_info.rc != 0
 
-- name: Set the qgroup limits
+- name: Set the qgroup limits for btrfs backing stores
   block:
     - name: Set the qgroup size|compression limits on machines
       command: "btrfs qgroup limit {{ item }} /var/lib/lxc/{{ inventory_hostname }}"
       changed_when: false
       delegate_to: "{{ physical_host }}"
       with_items:
-        - "-e {{ nspawn_host_qgroup_space_limit }}"
-        - "-c {{ nspawn_host_qgroup_compression_limit }}"
+        - "-e {{ lxc_host_btrfs_qgroup_space_limit }}"
+        - "-c {{ lxc_host_btrfs_qgroup_compression_limit }}"
       when:
-        - not nspawn_host_machine_quota_disabled
+        - not (lxc_host_btrfs_quota_disabled | bool)
   rescue:
     - name: Notice regarding quota system
       debug:
         msg: >-
           There was an error processing the setup of qgroups. Check the system
           to ensure they're available otherwise disable the quota system by
-          setting `nspawn_host_machine_quota_disabled` to true.
+          setting `lxc_host_btrfs_quota_disabled` to true.
   when:
     - lxc_container_backing_store == 'btrfs'

tasks/lxc_container_create_machinectl.yml

@@ -35,14 +35,14 @@
       changed_when: false
       delegate_to: "{{ physical_host }}"
       with_items:
-        - "-e {{ lxc_host_machine_qgroup_space_limit }}"
-        - "-c {{ lxc_host_machine_qgroup_compression_limit }}"
+        - "-e {{ lxc_host_btrfs_qgroup_space_limit }}"
+        - "-c {{ lxc_host_btrfs_qgroup_compression_limit }}"
       when:
-        - not lxc_host_machine_quota_disabled
+        - not (lxc_host_btrfs_quota_disabled | bool)
   rescue:
     - name: Notice regarding quota system
       debug:
         msg: >-
           There was an error processing the setup of qgroups. Check the system
           to ensure they're available otherwise disable the quota system by
-          setting `lxc_host_machine_quota_disabled` to true.
+          setting `lxc_host_btrfs_quota_disabled` to true.