On Mon, Nov 18, 2013 at 12:25 PM, Devananda van der Veen <
devananda....@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...@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.



>
>
>>
>> 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.

Doug



>
> Regards,
> Devananda
>
>
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