Enable periodic task to discover cell hosts when ironic is used

Starting with the Ocata release, bare metal nodes are no longer get recognized
by nova automatically. To avoid forcing users into running nova manage command
each time they enroll a node, we will have to allow enable the periodic task
to do so.

Change-Id: I8b0afac54dc9bd51dbe2ae4f237e4de50459be0f
Closes-Bug: #1697724

environments/services/ironic.yaml

@@ -2,3 +2,5 @@ resource_registry:
   OS::TripleO::Services::IronicApi: ../../puppet/services/ironic-api.yaml
   OS::TripleO::Services::IronicConductor: ../../puppet/services/ironic-conductor.yaml
   OS::TripleO::Services::NovaIronic: ../../puppet/services/nova-ironic.yaml
+parameter_defaults:
+  NovaSchedulerDiscoverHostsInCellsInterval: 15

puppet/services/nova-scheduler.yaml

@@ -45,6 +45,14 @@ parameters:
     default:
       tag: openstack.nova.scheduler
       path: /var/log/nova/nova-scheduler.log
+  NovaSchedulerDiscoverHostsInCellsInterval:
+    type: number
+    default: -1
+    description: >
+      This value controls how often (in seconds) the scheduler should
+      attempt to discover new hosts that have been added to cells.
+      The default value of -1 disables the periodic task completely.
+      It is recommended to set this parameter for deployments using Ironic.
 
 resources:
   NovaBase:
@@ -71,6 +79,7 @@ outputs:
           - nova::ram_allocation_ratio: '1.0'
             nova::scheduler::filter::scheduler_available_filters: {get_param: NovaSchedulerAvailableFilters}
             nova::scheduler::filter::scheduler_default_filters: {get_param: NovaSchedulerDefaultFilters}
+            nova::scheduler::discover_hosts_in_cells_interval: {get_param: NovaSchedulerDiscoverHostsInCellsInterval}
       step_config: |
         include tripleo::profile::base::nova::scheduler
       upgrade_tasks:

releasenotes/notes/baremetal-cell-hosts-cd5cf5aa8a33643c.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    When ``environments/services/ironic.yaml`` is used, enable periodic task
+    in nova-scheduler to automatically discover new nodes. Otherwise a user
+    has to run nova management command on controllers each time.