[openstack-dev] [Ironic] Nodeless Vendor Passthru API

Russell Haering russellhaering at gmail.com
Tue Mar 25 19:41:07 UTC 2014

On Tue, Mar 25, 2014 at 6:56 AM, Lucas Alvares Gomes
<lucasagomes at gmail.com>wrote:

> Hi Russell,
> Ironic allows drivers to expose a "vendor passthru" API on a Node. This
>> basically serves two purposes:
>> 1. Allows drivers to expose functionality that hasn't yet been
>> standardized in the Ironic API. For example, the Seamicro driver exposes
>> "attach_volume", "set_boot_device" and "set_node_vlan_id" passthru methods.
>> 2. Vendor passthru is also used by the PXE deploy driver as an internal
>> RPC callback mechanism. The deploy ramdisk makes calls to the passthru API
>> to signal for a deployment to continue once a server has booted.
>> For the purposes of this discussion I want to focus on case #2. Case #1
>> is certainly worth a separate discussion - we started this in
>> #openstack-ironic on Friday.
>> In the new agent we are working on, we want to be able to look up what
>> node the agent is running on, and eventually to be able to register a new
>> node automatically. We will perform an inventory of the server and submit
>> that to Ironic, where it can be used to map the agent to an existing Node
>> or to create a new one. Once the agent knows what node it is on, it will
>> check in with a passthru API much like that used by the PXE driver - in
>> some configurations this might trigger an immediate "continue" of an
>> ongoing deploy, in others it might simply register the agent as available
>> for new deploys in the future.
> Maybe another way to look up what node the agent is running on would be by
> looking at the MAC address of that node, having it on hand you could then
> GET /ports/detail and find which port has that MAC associated with it,
> after you find the port you can look at the node_uuid field which holds the
> UUID of the node which that port belongs to (All ports have a node_uuid,
> it's mandatory). So, right now you would need to list all the ports and
> find that MAC address there, but I got a review up that might help you with
> it by allowing you to get a port using its address as input:
> https://review.openstack.org/#/c/82773/ (GET /ports/detail?address=<mac>).
> What you think?

Right, we discussed this possibility as well. Internally that's actually
how the first iteration of our lookup call will work (mapping MAC addresses
to ports to nodes).

This can definitely be made to work, but in my mind it has a few

1. It limits how we can do lookups. In the future I'd like to be able to
consider serial numbers, hardware profiles, etc when trying to map an agent
to a node. Needing to expose an API for each of these is going to be
2. It limits how we do enrollment.
3. It forces us to expose more of the API to agents.

Items 1 and 2 seem like things that someone deploying Ironic is especially
likely to want to customize. For example, I might have some business
process around replacing NICs where I want to customize how a server is
uniquely identified (or even hit an external source to do it), or I might
want want to override enrollment to hook into Fuel.

While we can probably find a way to solve our current problem, how can we
generically solve the need for an agent to talk to a driver (either in
order to centralize orchestration, or because access to the database is
needed) without needing a Node UUID?

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