[placement][ironic][blazar] Summary: Placment + Ironic and Blazar

Chris Dent cdent+os at anticdent.org
Mon May 6 00:57:51 UTC 2019

There were a few different discussions about Ironic using placement
in various ways.

On line 117 (for now) of the placement PTG etherpad [1] there are
some notes about things that Ironic and Blazar could do for
reservations. These are not expected to require any changes in
placement. Dmitry and Tetsuro may have more to say about this.

There was also a separate discussion about the options for using
Placement do granular/detailed expression of available resources but
full/chunky consumption of resources in a context where Ironic is
running without Nova. That is:

* record inventory for baremental nodes that say the inventory of
   node1 is CPU:24,DISK_GB:1048576,MEMORY_MB=1073741824 (and
   whatever else).

* query something smaller (eg
   CPU:8,DISK_GB:524288,MEMORY_MB:536870912) in a GET

* include node1 in the results along with others, let the client
   side sort using provider summaries

* send back some mode of allocation that consumes the entire
   inventory of node1

There were a few different ideas on how to do that last step. One
idea would have required different resource providers have an
attribute that caused a change in behavior when allocated to. This
was dismissed as "too much business logic in the guts".

Another option was a flag on PUT /allocations that says "consume
everything, despite what I've said".

However, the option that was most favored was a new endpoint (name
to be determined later if we ever do this) that is for the purpose
of "fullly consuming the named resource provider".

Clearly this is something that fairly contrary to how Nova imagines
baremetal instances, but makes pretty good sense outside of the
context where people want to be able to use placement to
simultaneously get a flexible view of their baremetal resources and
also track them accurately.

There are no immediate plans to do this, but there are plans for
Dmitry to continue investigating the options and seeing what can or
cannot work. Having the feature described above would make things
cleaner. I have made a placeholder (and low priority) story [2] that
will link back to this email.

[1] https://etherpad.openstack.org/p/placement-ptg-train

[2] https://storyboard.openstack.org/#!/story/2005575

Chris Dent                       ٩◔̯◔۶           https://anticdent.org/
freenode: cdent                                         tw: @anticdent

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