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

Lucas Alvares Gomes lucasagomes at gmail.com
Tue Mar 25 13:56:12 UTC 2014

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?

> The point here is that we need a way for the agent driver to expose a
> top-level "lookup" API, which doesn't require a Node UUID in the URL.
> I've got a review (https://review.openstack.org/#/c/81919/) up which
> explores one possible implementation of this. It basically routes POSTs to
> /drivers/<driver_name>/vendor_passthru/<method_name> to a new method on the
> vendor interface.
> Importantly, I don't believe that this is a useful way for vendors to
> implement new consumer-facing functionality. If we decide to take this
> approach, we should reject drivers try to do so. It is intended *only* for
> internal communications with deploy agents.
> Another possibility is that we could create a new API service intended
> explicitly to serve use case #2 described above, which doesn't include most
> of the existing public paths. In our environment I expect us to allow
> agents whitelisted access to only two specific paths (lookup and checkin),
> but this might be a better way to achieve that.
> Thoughts?
> Thanks,
> Russell
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