Merge "Enable 'data' LVM group only for Docker devicemapper"

ansible/group_vars/all/compute

@@ -76,13 +76,19 @@ compute_lvm_groups: "{{ compute_lvm_groups_default + compute_lvm_groups_extra }}
 
 # Default list of compute volume groups. See mrlesmithjr.manage-lvm role for
 # format.
-compute_lvm_groups_default:
-  - "{{ compute_lvm_group_data }}"
+compute_lvm_groups_default: "{{ [compute_lvm_group_data] if compute_lvm_group_data_enabled | bool else [] }}"
 
 # Additional list of compute volume groups. See mrlesmithjr.manage-lvm role
 # for format.
 compute_lvm_groups_extra: []
 
+# Whether a 'data' LVM volume group should exist on compute hosts. By default
+# this contains a 'docker-volumes' logical volume for Docker volume storage. It
+# will also be used for Docker container and image storage if
+# 'docker_storage_driver' is set to 'devicemapper'. Default is true if
+# 'docker_storage_driver' is set to 'devicemapper', or false otherwise.
+compute_lvm_group_data_enabled: "{{ docker_storage_driver == 'devicemapper' }}"
+
 # Compute LVM volume group for data. See mrlesmithjr.manage-lvm role for
 # format.
 compute_lvm_group_data:

ansible/group_vars/all/controllers

@@ -87,13 +87,19 @@ controller_lvm_groups: "{{ controller_lvm_groups_default + controller_lvm_groups
 
 # Default list of controller volume groups. See mrlesmithjr.manage-lvm role for
 # format.
-controller_lvm_groups_default:
-  - "{{ controller_lvm_group_data }}"
+controller_lvm_groups_default: "{{ [controller_lvm_group_data] if controller_lvm_group_data_enabled | bool else [] }}"
 
 # Additional list of controller volume groups. See mrlesmithjr.manage-lvm role
 # for format.
 controller_lvm_groups_extra: []
 
+# Whether a 'data' LVM volume group should exist on controller hosts. By
+# default this contains a 'docker-volumes' logical volume for Docker volume
+# storage. It will also be used for Docker container and image storage if
+# 'docker_storage_driver' is set to 'devicemapper'. Default is true if
+# 'docker_storage_driver' is set to 'devicemapper', or false otherwise.
+controller_lvm_group_data_enabled: "{{ docker_storage_driver == 'devicemapper' }}"
+
 # Controller LVM volume group for data. See mrlesmithjr.manage-lvm role for
 # format.
 controller_lvm_group_data:

ansible/group_vars/all/seed

@@ -43,13 +43,19 @@ seed_lvm_groups: "{{ seed_lvm_groups_default + seed_lvm_groups_extra }}"
 
 # Default list of seed volume groups. See mrlesmithjr.manage-lvm role for
 # format.
-seed_lvm_groups_default:
-  - "{{ seed_lvm_group_data }}"
+seed_lvm_groups_default: "{{ [seed_lvm_group_data] if seed_lvm_group_data_enabled | bool else [] }}"
 
 # Additional list of seed volume groups. See mrlesmithjr.manage-lvm role for
 # format.
 seed_lvm_groups_extra: []
 
+# Whether a 'data' LVM volume group should exist on the seed. By default this
+# contains a 'docker-volumes' logical volume for Docker volume storage. It will
+# also be used for Docker container and image storage if
+# 'docker_storage_driver' is set to 'devicemapper'. Default is true if
+# 'docker_storage_driver' is set to 'devicemapper', or false otherwise.
+seed_lvm_group_data_enabled: "{{ docker_storage_driver == 'devicemapper' }}"
+
 # Seed LVM volume group for data. See mrlesmithjr.manage-lvm role for format.
 seed_lvm_group_data:
   vgname: data

ansible/group_vars/all/storage

@@ -88,13 +88,19 @@ storage_lvm_groups: "{{ storage_lvm_groups_default + storage_lvm_groups_extra }}
 
 # Default list of storage volume groups. See mrlesmithjr.manage-lvm role for
 # format.
-storage_lvm_groups_default:
-  - "{{ storage_lvm_group_data }}"
+storage_lvm_groups_default: "{{ [storage_lvm_group_data] if storage_lvm_group_data_enabled | bool else [] }}"
 
 # Additional list of storage volume groups. See mrlesmithjr.manage-lvm role
 # for format.
 storage_lvm_groups_extra: []
 
+# Whether a 'data' LVM volume group should exist on storage hosts. By default
+# this contains a 'docker-volumes' logical volume for Docker volume storage. It
+# will also be used for Docker container and image storage if
+# 'docker_storage_driver' is set to 'devicemapper'. Default is true if
+# 'docker_storage_driver' is set to 'devicemapper', or false otherwise.
+storage_lvm_group_data_enabled: "{{ docker_storage_driver == 'devicemapper' }}"
+
 # Storage LVM volume group for data. See mrlesmithjr.manage-lvm role for
 # format.
 storage_lvm_group_data:

doc/source/configuration/hosts.rst

@@ -520,11 +520,28 @@ via the ``seed_hypervisor_lvm_group_data_disks`` variable.
 LVM for Docker
 --------------
 
-The default LVM configuration is optimised for the ``devicemapper`` Docker
-storage driver, which requires a thin provisioned LVM volume. A second logical
-volume is used for storing Docker volume data, mounted at
-``/var/lib/docker/volumes``. Both logical volumes are created from a single
-``data`` volume group.
+.. note::
+
+   In Train and earlier releases of Kayobe, the ``data`` volume group was
+   always enabled by default.
+
+If the ``devicemapper`` Docker storage driver is in use, the default LVM
+configuration is optimised for it.  The ``devicemapper`` driver requires a thin
+provisioned LVM volume. A second logical volume is used for storing Docker
+volume data, mounted at ``/var/lib/docker/volumes``. Both logical volumes are
+created from a single ``data`` volume group.
+
+This configuration is enabled by the following variables, which default to
+``true`` if the ``devicemapper`` driver is in use or ``false`` otherwise:
+
+* ``compute_lvm_group_data_enabled``
+* ``controller_lvm_group_data_enabled``
+* ``seed_lvm_group_data_enabled``
+* ``storage_lvm_group_data_enabled``
+
+These variables can be set to ``true`` to enable the data volume group if the
+``devicemapper`` driver is not in use. This may be useful where the
+``docker-volumes`` logical volume is required.
 
 To use this configuration, a list of disks must be configured via the following
 variables:

releasenotes/notes/default-lvm-data-vg-f2848066975beeda.yaml

@@ -0,0 +1,15 @@
+---
+upgrade:
+  - |
+    The default LVM configuration is now empty for all hosts, unless they are
+    configured to use the ``devicemapper`` Docker storage driver (which is the
+    default, but is expected to change in a future release).
+
+    Note that while the default LVM configuration existed primarily for the
+    ``devicemapper`` driver, it also included a ``docker-volumes`` logical
+    volume mounted at ``/var/lib/docker/volumes`` for Docker volumes. If the
+    ``docker-volumes`` volume is required on a host which is not configured to
+    use the Docker ``devicemapper`` storage driver, the following variables may
+    be used to enable it: ``compute_lvm_group_data_enabled``,
+    ``controller_lvm_group_data_enabled``, ``seed_lvm_group_data_enabled``,
+    ``storage_lvm_group_data_enabled``.