Allow reusing defaults in per-node kernel_append_params

It may be convenient to use [pxe/redfish/...]kernel_append_params as
the universal defaults, while using {driver,instance}_info to only
append values. This change allows that by replacing %default% with
the value of the applicable configuration option.

An example use case: CoreOS requires an additional artifact (root
filesystem URL) when PXE booting.

While here, fix the PXE/iPXE interface documentation.

Change-Id: I829291ab5cc19ec2ca43bc45815d012697f0b408

5 files changed, 20 insertions, 28 deletions

diff --git a/ironic/drivers/modules/ilo/boot.py b/ironic/drivers/modules/ilo/boot.py
index 5087e3998..7f5c5adcf 100644
--- a/ironic/drivers/modules/ilo/boot.py
+++ b/ironic/drivers/modules/ilo/boot.py
@@ -74,12 +74,8 @@ OPTIONAL_PROPERTIES = {
     'ilo_add_certificates': _("Boolean value that indicates whether the "
                               "certificates require to be added to the "
                               "iLO."),
-    'kernel_append_params': _("Additional kernel parameters to pass down "
-                              "to instance kernel. These parameters can "
-                              "be consumed by the kernel or by the "
-                              "applications by reading /proc/cmdline. "
-                              "Mind severe cmdline size limit. Overrides "
-                              "[ilo]/kernel_append_params ironic option.")
+    'kernel_append_params': driver_utils.KERNEL_APPEND_PARAMS_DESCRIPTION %
+    {'option_group': 'ilo'},
 }
 COMMON_PROPERTIES = REQUIRED_PROPERTIES
 
diff --git a/ironic/drivers/modules/irmc/boot.py b/ironic/drivers/modules/irmc/boot.py
index 1195a0670..84964bd2f 100644
--- a/ironic/drivers/modules/irmc/boot.py
+++ b/ironic/drivers/modules/irmc/boot.py
@@ -80,13 +80,8 @@ OPTIONAL_PROPERTIES = {
           "the IPv4 subnet mask that the storage network is configured to "
           "utilize, in a range between 1 and 31 inclusive. This is necessary "
           "for booting a node from a remote iSCSI volume. Optional."),
-    'kernel_append_params': _("Additional kernel parameters to pass down to "
-                              "instance kernel. These parameters can be "
-                              "consumed by the kernel or by the applications "
-                              "by reading /proc/cmdline. Mind severe cmdline "
-                              "size limit. Overrides "
-                              "[irmc]/kernel_append_params ironic "
-                              "option."),
+    'kernel_append_params': driver_utils.KERNEL_APPEND_PARAMS_DESCRIPTION %
+    {'option_group': 'irmc'},
 }
 
 COMMON_PROPERTIES = REQUIRED_PROPERTIES.copy()
diff --git a/ironic/drivers/modules/pxe_base.py b/ironic/drivers/modules/pxe_base.py
index a89c9e443..317b65b85 100644
--- a/ironic/drivers/modules/pxe_base.py
+++ b/ironic/drivers/modules/pxe_base.py
@@ -50,13 +50,8 @@ RESCUE_PROPERTIES = {
                         'required for rescue mode.'),
 }
 OPTIONAL_PROPERTIES = {
-    'kernel_append_params': _("Additional kernel parameters to pass down to "
-                              "instance kernel. These parameters can be "
-                              "consumed by the kernel or by the applications "
-                              "by reading /proc/cmdline. Mind severe cmdline "
-                              "size limit. Overrides "
-                              "[pxe]/kernel_append_params ironic "
-                              "option."),
+    'kernel_append_params': driver_utils.KERNEL_APPEND_PARAMS_DESCRIPTION %
+    {'option_group': 'pxe'},
 }
 COMMON_PROPERTIES = REQUIRED_PROPERTIES.copy()
 COMMON_PROPERTIES.update(driver_utils.OPTIONAL_PROPERTIES)
diff --git a/ironic/drivers/modules/redfish/boot.py b/ironic/drivers/modules/redfish/boot.py
index 55c826fc6..1ce05ced9 100644
--- a/ironic/drivers/modules/redfish/boot.py
+++ b/ironic/drivers/modules/redfish/boot.py
@@ -46,13 +46,8 @@ OPTIONAL_PROPERTIES = {
                               "driver should use virtual media USB or floppy "
                               "device for passing configuration information "
                               "to the ramdisk. Defaults to False. Optional."),
-    'kernel_append_params': _("Additional kernel parameters to pass down to "
-                              "instance kernel. These parameters can be "
-                              "consumed by the kernel or by the applications "
-                              "by reading /proc/cmdline. Mind severe cmdline "
-                              "size limit. Overrides "
-                              "[redfish]/kernel_append_params ironic "
-                              "option."),
+    'kernel_append_params': driver_utils.KERNEL_APPEND_PARAMS_DESCRIPTION %
+    {'option_group': 'redfish'},
     'bootloader': _("URL or Glance UUID  of the EFI system partition "
                     "image containing EFI boot loader. This image will be "
                     "used by ironic when building UEFI-bootable ISO "
diff --git a/ironic/drivers/utils.py b/ironic/drivers/utils.py
index 5e1596eb4..fc5cdcf0d 100644
--- a/ironic/drivers/utils.py
+++ b/ironic/drivers/utils.py
@@ -384,6 +384,17 @@ OPTIONAL_PROPERTIES = {
 }
 
 
+KERNEL_APPEND_PARAMS_DESCRIPTION = _(
+    "Additional kernel parameters to pass down to instance kernel. "
+    "These parameters can be consumed by the kernel or by the applications "
+    "by reading /proc/cmdline. Mind severe cmdline size limit. "
+    "When used with virtual media, only applies to ISO images that Ironic "
+    "builds, but not to pre-built ISOs provided via e.g. deploy_iso. "
+    "Overrides the [%(option_group)s]/kernel_append_params configuration "
+    "option, use %%default%% to insert its value."
+)
+
+
 def get_kernel_append_params(node, default):
     """Get the applicable kernel params.
 
@@ -399,7 +410,7 @@ def get_kernel_append_params(node, default):
     for location in ('instance_info', 'driver_info'):
         result = getattr(node, location).get('kernel_append_params')
         if result is not None:
-            return result
+            return result.replace('%default%', default or '')
 
     return default