Remove config option [dpm].host

The DPM driver manages so-called "cpc-subsets". Basically, this is
a logically portion cut out of a system z CPC. For the Nova driver,
this emulates a "host". This results in this multiplicity:

    DPM Driver 1 --- 1 CPC-subset (=host) * --- 1 CPC

Having the two config options "[DEFAULT].host" and "[dpm].host", which
mean the same thing, could be confusing for a user. Also, this can
lead to issues if both are not in sync, for example during the
Nova<->Neutron communication where the NICs get created.

To resolve this, this change removes the config option "[dpm].host"
and uses "[DEFAULT].host" only. As the config option wasn't yet part
of any release, we don't need to do the usual deprecation policy.

closes bug: 1655043

Change-Id: Ibb2c23e248c4390e2ec19e7aa9811abdc24fea25

devstack/local.conf.singlenode.nova_neutron

@@ -27,7 +27,6 @@ host = foo
 max_instances = 10
 max_memory = 5000
 max_processors = 2
-host = foo
 cpc_object_id = <cpc-object-id>
 hmc_password = <password>
 hmc_username = <user>

devstack/plugin.sh

@@ -54,7 +54,6 @@ function configure_nova_dpm {
     iniset $NOVA_CONF dpm hmc $HMC
     iniset $NOVA_CONF dpm hmc_username $HMC_USERNAME
     iniset $NOVA_CONF dpm hmc_password $HMC_PASSWORD
-    iniset $NOVA_CONF dpm host $HOST
     iniset $NOVA_CONF dpm cpc_object_id $CPC_OBJECT_ID
     iniset $NOVA_CONF dpm max_processors $MAX_PROC
     iniset $NOVA_CONF dpm max_memory $MAX_MEM

devstack/settings

@@ -14,7 +14,6 @@ DPM_DRIVER=dpm.driver.DPMDriver
 HMC=$HMC
 HMC_USERNAME=$HMC_USERNAME
 HMC_PASSWORD=$HMC_PASSWORD
-HOST=$HOST
 CPC_OBJECT_ID=$CPC_OBJECT_ID
 MAX_PROC=$MAX_PROC
 MAX_MEM=$MAX_MEM

nova_dpm/conf/dpm.py

@@ -27,8 +27,6 @@ value `dpm.DPMDriver`.
 """
 
 ALL_DPM_OPTS = [
-    cfg.StrOpt('host', default='', required=True, help="""
-    Name of the OpenStack hypervisor host"""),
     cfg.IntOpt('max_processors', help="""
     Maximum number of shared physical IFL processors on the target CPC that can
     be used for this OpenStack hypervisor host"""),

nova_dpm/virt/dpm/driver.py

@@ -73,7 +73,7 @@ class DPMDriver(driver.ComputeDriver):
         LOG.debug("init_host")
 
         # retrieve from ncpu service configurationfile
-        self._conf = {'cpcsubset_name': CONF.dpm.host,
+        self._conf = {'cpcsubset_name': CONF.host,
                       'cpc_object_id': CONF.dpm.cpc_object_id,
                       'max_processors': CONF.dpm.max_processors,
                       'max_memory_mb': CONF.dpm.max_memory,