[openstack-dev] [tripleo] [ironic] Need to update kernel parameters on local boot

Yolanda Robla Mota yroblamo at redhat.com
Mon Nov 28 15:36:45 UTC 2016

Hi, good afternoon

I wanted to start an email thread about how to properly setup kernel parameters on local boot, for our overcloud images on TripleO.
These parameters may vary depending on the needs of our end users, and even can be different ( for different roles ) per deployment. As an example, we need it for:
- enable FIPS kernel in terms of security (https://bugs.launchpad.net/tripleo/+bug/1640235)
- enable functionality for DPDK/SR-IOV (https://review.openstack.org/#/c/331564/)
- enable rd.iscsi.firmware=1 flag (this for the ramdisk image)
- etc..

So far, the solutions we got were on several directions:

1. Update the golden overcloud-full image with virt-customize, modifying /etc/default/grub settings according to our needs: this is a manual process, not really driven by TripleO. End users will want to avoid manual steps as much as possible. Also if we announce that OpenStack ships features in TripleO like DPDK, SR-IOV... doesn't make sense to tell end users that if they want to consume that feature, they need to do manual updates on the image. It shall be natively supported, or configurable per TripleO environments.

2. Create our own images using diskimage-builder and custom elements: in this case, we have the problem that the partners will loose support, as building their own images is good for upstream, but not accepted into the OSP environment. Also the combination of images needed can be huge, that can be a blocker for QA.

3. Add Ironic support for it. Images can be uploaded to glance, and some properties can be set on metadata, like a json with kernel parameters. Ironic will modify these kernel parameters when deploying the image (in a similar way that when it installs bootloader, or generates partitions).

4. Configure it post-deployment: there can be some puppet element that updates kernel parameters. But it will need a node reboot to be applied, and it's very far from being optimal and acceptable for the end users. Reboots are slow, they can be a problem depending on the number of nodes/hardware, and also the timing of reboot shall be totally controlled (after all puppet has been applied properly).

In the first three cases, we also hit the problem that TripleO only accepts one single overcloud image for all deployments - there is no way to instruct TripleO to upload and use several images, depending on the node type (although Ironic supports it). Also, we are worried about upgrade paths if we do image customizations. We need a clear way to move forward on it.

So, we'd like to discuss the possible options there and the action items to take (raise bugs, create some blueprints...). To summarize, our end goal is the following:

- need to map overcloud-full images to roles
- need to be done in an automated way, no manual steps enforced, and in a way that can pass properly quality controls
- reboots are sub-optimal

What are your thoughts there?


Yolanda Robla
yroblamo at redhat.com
Principal Software Engineer - NFV Partner Engineer

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