Open Stack

On 27 March 2014 06:28, Eoghan Glynn <eglynn at redhat.com> wrote:
>
>
>> On 3/25/2014 1:50 PM, Matt Wagner wrote:
>> > This would argue to me that the easiest thing for Ceilometer might be
>> > to query us for IPMI stats, if the credential store is pluggable.
>> > "Fetch these bare metal statistics" doesn't seem too off-course for
>> > Ironic to me. The alternative is that Ceilometer and Ironic would both
>> > have to be configured for the same pluggable credential store.
>>
>> There is already a blueprint with a proposed patch here for Ironic to do
>> the querying:
>> https://blueprints.launchpad.net/ironic/+spec/send-data-to-ceilometer.
>
> Yes, so I guess there are two fundamentally different approaches that
> could be taken here:
>
> 1. ironic controls the cadence of IPMI polling, emitting notifications
>    at whatever frequency it decides, carrying whatever level of
>    detail/formatting it deems appropriate, which are then consumed by
>    ceilometer which massages these provided data into usable samples
>
> 2. ceilometer acquires the IPMI credentials either via ironic or
>    directly from keystone/barbican, before calling out over IPMI at
>    whatever cadence it wants and transforming these raw data into
>    usable samples
>
> IIUC approach #1 is envisaged by the ironic BP[1].
>
> The advantage of approach #2 OTOH is that ceilometer is in the driving
> seat as far as cadence is concerned, and the model is far more
> consistent with how we currently acquire data from the hypervisor layer
> and SNMP daemons.

The downsides of #2 are:
 - more machines require access to IPMI on the servers (if a given
ceilometer is part of the deployed cloud, not part of the minimal
deployment infrastructure). This sets of security red flags in some
organisations.
 - multiple machines (ceilometer *and* Ironic) talking to the same
IPMI device. IPMI has a limit on sessions, and in fact the controllers
are notoriously buggy - having multiple machines talking to one IPMI
device is a great way to exceed session limits and cause lockups.

These seem fundamental showstoppers to me.

-Rob

-- 
Robert Collins <rbtcollins at hp.com>
Distinguished Technologist
HP Converged Cloud