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Doug Hellmann wrote on 2013-11-19:
> 
> On Mon, Nov 18, 2013 at 12:25 PM, Devananda van der Veen <devananda.vdv at gmail.com> wrote:
> 
> 
> 	Hi Lianhao Lu,
> 
> 	I briefly summarized my recollection of that session in this blueprint:
> 
> 	https://blueprints.launchpad.net/ironic/+spec/add-ceilometer-agent
> 
> 
> 	I've responded to your questions inline as well.
> 
> 
> 	On Sun, Nov 17, 2013 at 10:24 PM, Lu, Lianhao <lianhao.lu at intel.com> wrote:
> 
> 
> 		Hi stackers,
> 
> 		During the summit session Expose hardware sensor (IPMI) data
> https://etherpad.openstack.org/p/icehouse-summit-ceilometer-hardware-sensors, it was proposed to deploy a ceilometer agent next to
> the ironic conductor to the get the ipmi data. Here I'd like to ask some questions to figure out what's the current missing pieces in ironic
> and ceilometer for that proposal.
> 
> 		1. Just double check, ironic won't provide API to get IPMI data, right?
> 
> 
> 
> 	Correct. This was generally felt to be unnecessary.
> 
> 
> 		2. If deploying a ceilometer agent next to the ironic conductor, how does the agent talk to the conductor? Through rpc?
> 
> 
> 
> 	My understanding is that ironic-conductor will emit messages to the ceilimeter agent, and the communication is one-way. These could
> be triggered by a periodic task, or by some other event within Ironic, such as a change in the power state of a node.
> 
> 
> Cool, so this eliminates the need for a separate agent. The ceilometer work can be done in the collector, to receive the new messages.
> 
Does this means we lose the ability to specify the different polling interval for different monitoring data, like we have in ceilometer pipeline? 

> 
> 		3. Does the current ironic conductor have rpc_method to support getting generic ipmi data, i.e. let the rpc_method caller
> specifying arbitrary netfn/command to get any type of ipmi data?
> 
> 
> 
> 	No, and as far as I understand, it doesn't need one.
> 
> 
> It would only need that if we were going to poll for the data, but if ironic is emitting notifications then we don't have to do that.
> 
> 		4. I believe the ironic conductor uses some kind of node_id to associate the bmc with its credentials, right? If so, how can the
> ceilometer agent get those node_ids to ask the ironic conductor to poll the ipmi data? And how can the ceilometer agent extract
> meaningful information from that node_id to set those fields in the ceilometer Sample(e.g. recource_id, project_id, user_id, etc.) to identify
> which physical node the ipmi data is coming from?
> 
> 	This question perhaps requires a longer answer.
> 
> 	Ironic references physical machines (nodes) internally with an integer node_id and externally with a standard uuid. When a Nova
> instance is created, it will be associated to a node, that node will have a reference to the nova instance_uuid which is exposed in our API,
> and can be passed to Ceilometer's agent. I believe that nova instance_uuid will enable ceilometer to detect the project, user, etc.
> 
> 
> If ironic has those values (at least the project), and can include them in the notification payload, that will make processing the incoming
> notifications significantly less expensive.
> 
> 
> 	Should Ironic emit messages regarding nodes which are not provisioned? Physical machines that don't have a tenant instance on them
> are not associated to any project, user, tenant, quota, etc, so I suspect that we shouldn't notify about them. It would be like tracking the
> unused disks in a SAN.
> 
> 
> I don't think it would be useful, but if someone else does then it seems OK to include them.

I think it'd better for Ironic to emit those data in case some users want to collect them, at least Ironic should have a configuration setting to emit those kind of data.

-Lianhao