175 lines
4.2 KiB
ReStructuredText
175 lines
4.2 KiB
ReStructuredText
..
|
|
This work is licensed under a Creative Commons Attribution 3.0 Unported
|
|
License.
|
|
|
|
http://creativecommons.org/licenses/by/3.0/legalcode
|
|
|
|
========================================
|
|
Override PXE options via Glance property
|
|
========================================
|
|
|
|
https://bugs.launchpad.net/ironic/+bug/1526409
|
|
|
|
The proposal presents the work required to allow PXE boot an image using
|
|
a specific kernel command line for that image.
|
|
|
|
Problem description
|
|
===================
|
|
|
|
Some images requires having specific kernel command line to boot
|
|
correctly. Currently, Ironic tries to determine things like the root
|
|
filesystem the image is on ("root=" kernel command line) by getting the
|
|
UUID of the image filesystem and setting as the root= parameter. This is
|
|
not correct for all images because some may need to boot from a different
|
|
root filesystem, e.g:
|
|
|
|
* The device path of its LVM volume [root=/dev/mapper/vg-lv_root]
|
|
* From one squashfs filesystem [root=live:<path>]
|
|
* A btrfs subvolume [root=/dev/disk/by-uuid/<UUID of btrfs-root>]
|
|
|
|
As a real example, the Fedora Atomic uses ``lvm`` and ``ostree``. It
|
|
requires a kernel command line as the example below to boot properly::
|
|
|
|
nofb nomodeset vga=normal console=tty1 no_timer_check
|
|
rd.lvm.lv=atomicos/root root=/dev/mapper/atomicos-root
|
|
ostree=/ostree/boot.0/fedora-atomic/a002a2c2e44240db614e09e82c/0
|
|
|
|
Proposed change
|
|
===============
|
|
|
|
In the same way Ironic look at the Glance image properties to find out the
|
|
Glance UUID for the image's kernel and ramdisk (kernel_id and ramdisk_id)
|
|
and populate the node's ``instance_info`` field with the ``kernel`` and
|
|
``ramdisk`` keys.
|
|
|
|
This spec propose having a new image's property field called
|
|
``kernel_cmdline`` that Ironic will look at, and if present, it will
|
|
populate the node's ``instance_info`` field with a ``kernel_cmdline``
|
|
key.
|
|
|
|
If the ``instance_info.kernel_cmdline`` is populate Ironic will skip
|
|
getting the root partition filesystem UUID and will use the command
|
|
line from the ``instance_info`` field instead of the default one in
|
|
the template. It's important to note that the values present at the
|
|
``pxe_append_params`` configuration option will still be appended at
|
|
the end of the image's custom kernel command line by Ironic.
|
|
|
|
Setting the keys in the ``instance_info`` field is important because
|
|
it also allows Ironic to operate in standalone mode without Glance.
|
|
|
|
Alternatives
|
|
------------
|
|
Always use whole disk images when deploying images that requires a
|
|
specific kernel command line
|
|
|
|
Data model impact
|
|
-----------------
|
|
None
|
|
|
|
State Machine Impact
|
|
--------------------
|
|
None
|
|
|
|
REST API impact
|
|
---------------
|
|
None
|
|
|
|
Client (CLI) impact
|
|
-------------------
|
|
None
|
|
|
|
RPC API impact
|
|
--------------
|
|
None
|
|
|
|
Driver API impact
|
|
-----------------
|
|
None
|
|
|
|
Nova driver impact
|
|
------------------
|
|
None
|
|
|
|
Ramdisk impact
|
|
--------------
|
|
|
|
N/A
|
|
|
|
.. NOTE: This section was not present at the time this spec was approved.
|
|
|
|
Security impact
|
|
---------------
|
|
None
|
|
|
|
Other end user impact
|
|
---------------------
|
|
None
|
|
|
|
Scalability impact
|
|
------------------
|
|
None
|
|
|
|
Performance Impact
|
|
------------------
|
|
None
|
|
|
|
Other deployer impact
|
|
---------------------
|
|
|
|
Deployers that wants to deploy an image with a specific kernel command
|
|
line should know and set it in Glance image's property prior to trying
|
|
to boot the image.
|
|
|
|
Developer impact
|
|
----------------
|
|
None
|
|
|
|
Implementation
|
|
==============
|
|
|
|
Assignee(s)
|
|
-----------
|
|
|
|
Primary assignee:
|
|
lucasagomes <lucasagomes@gmail.com>
|
|
|
|
Other contributors:
|
|
None
|
|
|
|
Work Items
|
|
----------
|
|
|
|
* Make Ironic look at the ``kernel_cmdline`` image property in Glance
|
|
and if present set it to the node's ``instance_info`` field
|
|
|
|
* When preparing to boot the user's image, make Ironic check if the
|
|
node's ``instance_info`` field contains a key called ``kernel_cmdline``
|
|
(along with ``kernel_id`` and ``ramdisk_id``) and if so, use that kernel
|
|
command line to boot the image.
|
|
|
|
Dependencies
|
|
============
|
|
None
|
|
|
|
Testing
|
|
=======
|
|
|
|
* Unit Tests
|
|
|
|
Upgrades and Backwards Compatibility
|
|
====================================
|
|
None
|
|
|
|
Documentation Impact
|
|
====================
|
|
|
|
The Ironic deploy documentation will be updated to reflect the changes
|
|
made by this spec.
|
|
|
|
References
|
|
==========
|
|
|
|
* `Kernel parameters <https://www.kernel.org/doc/Documentation/kernel-parameters.txt>`_
|
|
|
|
* `Project atomic <http://www.projectatomic.io>`_
|