Support extra PXE kernel arguments for Inspector

As an operator I want to be able to specify additional kernel arguments
for nodes being inspected by ironic inspector so that I can pass
arguments to Ironic Python Agent (IPA).

A number of optional features in IPA are configured via kernel command
line arguments, e.g. ipa-collect-lldp.

This change allows additional kernel arguments to be provided for use
by the IPA ramdisk during inspection.

Change-Id: I547596a8108765383f291da690196f3222b59d79
Closes-Bug: #1685876

playbooks/roles/bifrost-ironic-install/README.md

@@ -210,6 +210,10 @@ inspector_default_node_driver: The default driver to utilize when adding
                                setting for their install environment if
                                an alternative default driver is required.
 
+inspector_extra_kernel_options: String value, default undefined. Extra
+                                kernel parameters for the inspector default
+                                PXE configuration.
+
 ### Virtual Environment Install
 
 Bifrost can install ironic into a python virtual environment using the

playbooks/roles/bifrost-ironic-install/defaults/main.yml

@@ -141,6 +141,10 @@ inspector_port_addition: "pxe"
 # Note: inspector_keep_ports has three valid values: all, present, added
 inspector_keep_ports: "present"
 
+# String value containing extra kernel parameters for the inspector default
+# PXE configuration.
+#inspector_extra_kernel_options:
+
 # Inspector defaults
 inspector:
   discovery:

playbooks/roles/bifrost-ironic-install/templates/inspector-default-boot-ipxe.j2

@@ -5,6 +5,6 @@ dhcp || reboot
 goto introspect
 
 :introspect
-kernel {{ ipa_kernel_url }} ipa-inspection-callback-url=http://{{ hostvars[inventory_hostname]['ansible_' + ans_network_interface ]['ipv4']['address'] }}:5050/v1/continue systemd.journald.forward_to_console=yes ip=${ip}:${next-server}:${gateway}:${netmask} BOOTIF=${mac} nofb nomodeset vga=normal console=ttyS0
+kernel {{ ipa_kernel_url }} ipa-inspection-callback-url=http://{{ hostvars[inventory_hostname]['ansible_' + ans_network_interface ]['ipv4']['address'] }}:5050/v1/continue systemd.journald.forward_to_console=yes ip=${ip}:${next-server}:${gateway}:${netmask} BOOTIF=${mac} nofb nomodeset vga=normal console=ttyS0 {{ inspector_extra_kernel_options | default('') }}
 initrd {{ ipa_ramdisk_url }}
 boot

releasenotes/notes/inspector-pxe-args-c65acb610507ab08.yaml

@@ -0,0 +1,11 @@
+---
+features:
+  - |
+    Allows additional kernel arguments to be specified in inspector PXE config.
+
+    A number of optional features in the Ironic Python Agent (IPA) are
+    configured via kernel command line arguments, e.g. ``ipa-collect-lldp``.
+
+    It is now possible to specify additional kernel arguments for use by the
+    IPA ramdisk during inspection with the ``inspector_extra_kernel_options``
+    variable.