Make pxelinux.cfg folder configurable

Some operators may wish to utilize different default folders
for their bootloaders to search for refernces to the asociated
configuration file.

This patch adds an option to the configuration file that allows
operators to change the default.

Change-Id: I9b8f97868aea74c1b1b458fe8f16ada1ff4ea579

ironic/common/pxe_utils.py

@@ -32,7 +32,7 @@ CONF = cfg.CONF
 
 LOG = logging.getLogger(__name__)
 
-PXE_CFG_DIR_NAME = 'pxelinux.cfg'
+PXE_CFG_DIR_NAME = CONF.pxe.pxe_config_subdir
 
 DHCP_CLIENT_ID = '61'  # rfc2132
 DHCP_TFTP_SERVER_NAME = '66'  # rfc2132

ironic/conf/pxe.py

@@ -92,6 +92,13 @@ opts = [
     cfg.StrOpt('pxe_bootfile_name',
                default='pxelinux.0',
                help=_('Bootfile DHCP parameter.')),
+    cfg.StrOpt('pxe_config_subdir',
+               default='pxelinux.cfg',
+               help=_('Directory in which to create symbolic links which '
+                      'represent the MAC or IP address of the the ports on '
+                      'a node and allow boot loaders to load the PXE '
+                      'file for the node. This directory name is relative '
+                      'to the PXE or iPXE folders.')),
     cfg.StrOpt('uefi_pxe_bootfile_name',
                default='bootx64.efi',
                help=_('Bootfile DHCP parameter for UEFI boot mode.')),

releasenotes/notes/allow-pxelinux-config-folder-to-be-defined-da0ddd397d58dcc8.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    Adds a new configuration option ``[pxe]pxe_config_subdir`` to allow
+    operators to define the specific directory that may be used inside of
+    ``/tftpboot`` or ``/httpboot`` for a boot loader to locate the
+    configuration file for the node. This option defaults to ``pxelinux.cfg``
+    which is the directory that the Syslinux `pxelinux.0` bootloader utilized.
+    Operators may wish to change the directory name if they are using other boot
+    loaders such as `GRUB` or `iPXE`.