Add max_disk_devices_to_attach parameter

This adds parameter that controls `compute/max_disk_devices_to_attach`
Nova parameter which sets maximum number of disk devices
allowed to attach to a single server.

Change-Id: I2750f445f420bbee7e905d59efae9c642142b7e0

manifests/compute.pp

@@ -172,6 +172,16 @@
 #   (optional) whether to wait for ``network-vif-plugged`` events before starting guest transfer
 #   Defaults to $::os_service_default
 #
+# [*max_disk_devices_to_attach*]
+#   (optional) specifies max number of devices that can be attached
+#   to a single server.
+#   Note that the number of disks supported by an server depends
+#   on the bus used. For example, the ide disk bus is limited
+#   to 4 attached devices. The configured maximum is enforced
+#   during server create, rebuild, evacuate, unshelve, live migrate,
+#   and attach volume.
+#   Defaults to $::os_service_default
+#
 # DEPRECATED PARAMETERS
 #
 # [*vnc_keymap*]
@@ -234,6 +244,7 @@ class nova::compute (
   $neutron_physnets_numa_nodes_mapping         = {},
   $neutron_tunnel_numa_nodes                   = [],
   $live_migration_wait_for_vif_plug            = $::os_service_default,
+  $max_disk_devices_to_attach                  = $::os_service_default,
   # DEPRECATED PARAMETERS
   $vnc_keymap                                  = undef,
   $neutron_enabled                             = undef,
@@ -368,6 +379,7 @@ class nova::compute (
     'compute/consecutive_build_service_disable_threshold':
       value => $consecutive_build_service_disable_threshold;
     'compute/live_migration_wait_for_vif_plug':  value => $live_migration_wait_for_vif_plug;
+    'compute/max_disk_devices_to_attach':        value => $max_disk_devices_to_attach;
   }
 
   ensure_resource('nova_config', 'DEFAULT/allow_resize_to_same_host', { value => $allow_resize_to_same_host })

releasenotes/notes/add_max_disk_devices_to_attach-061c48948416d8c5.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    Add parameter `max_disk_devices_to_attach` that specifies
+    max number of devices that can be attached to a single server.
+    Note that the number of disks supported by an server depends
+    on the bus used. For example, the ide disk bus is limited
+    to 4 attached devices. The configured maximum is enforced
+    during server create, rebuild, evacuate, unshelve, live migrate,
+    and attach volume.

spec/classes/nova_compute_spec.rb

@@ -39,6 +39,7 @@ describe 'nova::compute' do
       it { is_expected.to contain_nova_config('compute/consecutive_build_service_disable_threshold').with_value('<SERVICE DEFAULT>') }
       it { is_expected.to contain_nova_config('DEFAULT/reserved_huge_pages').with_value('<SERVICE DEFAULT>') }
       it { is_expected.to contain_nova_config('compute/live_migration_wait_for_vif_plug').with_value('<SERVICE DEFAULT>') }
+      it { is_expected.to contain_nova_config('compute/max_disk_devices_to_attach').with_value('<SERVICE DEFAULT>') }
 
       it { is_expected.to_not contain_package('cryptsetup').with( :ensure => 'present' )}
 
@@ -100,6 +101,7 @@ describe 'nova::compute' do
           :verify_glance_signatures           => true,
           :consecutive_build_service_disable_threshold => '9',
           :live_migration_wait_for_vif_plug   => true,
+          :max_disk_devices_to_attach         => 20,
         }
       end
 
@@ -161,6 +163,8 @@ describe 'nova::compute' do
 
       it { is_expected.to contain_nova_config('compute/live_migration_wait_for_vif_plug').with_value(true) }
 
+      it { is_expected.to contain_nova_config('compute/max_disk_devices_to_attach').with_value(20) }
+
       it 'configures nova config_drive_format to vfat' do
         is_expected.to contain_nova_config('DEFAULT/config_drive_format').with_value('vfat')
         is_expected.to_not contain_package('genisoimage').with(