Move place_loaders_for_boot to boot driver __init__

Host preparation file writing is already done by the __init__ method
of iPXEBoot. This change moves place_loaders_for_boot calls to
iPXEBoot and PXEBoot to be consistent, and to only write the files
when that driver is enabled.

This will mean multiple writes of the same file when subclasses of
these drivers are also enabled, but this overhead will be negligible.

Change-Id: I7e17f4d1a54cd6c5d1a4bf006a0d42db8d123a46

ironic/conductor/base_manager.py

@@ -31,7 +31,6 @@ from ironic.common import driver_factory
 from ironic.common import exception
 from ironic.common import hash_ring
 from ironic.common.i18n import _
-from ironic.common import pxe_utils
 from ironic.common import release_mappings as versions
 from ironic.common import rpc
 from ironic.common import states
@@ -88,11 +87,9 @@ class BaseConductorManager(object):
     def prepare_host(self):
         """Prepares host for initialization
 
-        Prepares the conductor for basic operation by removing any
-        existing transitory node power states and reservations which
-        were previously held by this host. Once that has been completed,
-        bootloader assets, if configured, are staged for network (PXE) boot
-        operations.
+        Prepares the conductor for basic operation by removing any existing
+        transitory node power states and reservations which were previously
+        held by this host.
 
         Under normal operation, this is also when the initial database
         connectivity is established for the conductor's normal operation.
@@ -112,8 +109,6 @@ class BaseConductorManager(object):
         self.dbapi.clear_node_target_power_state(self.host)
         # clear all locks held by this conductor before registering
         self.dbapi.clear_node_reservations_for_conductor(self.host)
-        pxe_utils.place_loaders_for_boot(CONF.pxe.tftp_root)
-        pxe_utils.place_loaders_for_boot(CONF.deploy.http_root)
 
     def init_host(self, admin_context=None):
         """Initialize the conductor host.

ironic/drivers/modules/ipxe.py

@@ -16,6 +16,7 @@ iPXE Boot Interface
 """
 
 from ironic.common import pxe_utils
+from ironic.conf import CONF
 from ironic.drivers import base
 from ironic.drivers.modules import pxe_base
 
@@ -28,3 +29,6 @@ class iPXEBoot(pxe_base.PXEBaseMixin, base.BootInterface):
 
     def __init__(self):
         pxe_utils.create_ipxe_boot_script()
+        pxe_utils.place_loaders_for_boot(CONF.deploy.http_root)
+        # This is required to serve the iPXE binary via tftp
+        pxe_utils.place_loaders_for_boot(CONF.pxe.tftp_root)

ironic/drivers/modules/pxe.py

@@ -20,9 +20,11 @@ from oslo_log import log as logging
 
 from ironic.common import boot_devices
 from ironic.common.i18n import _
+from ironic.common import pxe_utils
 from ironic.common import states
 from ironic.conductor import task_manager
 from ironic.conductor import utils as manager_utils
+from ironic.conf import CONF
 from ironic.drivers import base
 from ironic.drivers.modules import agent_base
 from ironic.drivers.modules import deploy_utils
@@ -36,6 +38,10 @@ class PXEBoot(pxe_base.PXEBaseMixin, base.BootInterface):
 
     capabilities = ['ramdisk_boot', 'pxe_boot']
 
+    def __init__(self):
+        pxe_utils.place_loaders_for_boot(CONF.deploy.http_root)
+        pxe_utils.place_loaders_for_boot(CONF.pxe.tftp_root)
+
 
 class PXEAnacondaDeploy(agent_base.AgentBaseMixin, agent_base.HeartbeatMixin,
                         base.DeployInterface):