| Posted | Nick | Remark | |
|---|---|---|---|
| #openstack-nova - 2025-03-06 | |||
| 15:38:34 | sean-k-mooney | as is sid i think, i could be wrong about this, that for evacuate we do not have a migration uuid becuase its actully not a "move op" in that sence it just rebuidl to a new host | |
| 15:38:57 | sean-k-mooney | so for evacuate i think we extend the single allcoaiton with rp for the dest | |
| 15:39:18 | sean-k-mooney | i could be wrong about that because i know we change that at some point | |
| 15:39:26 | sean-k-mooney | i would have to look at the detail | |
| 15:40:49 | dansmith | yeah idk, I'm more familiar with the cold migrate case, which is clearly broken already | |
| 15:41:05 | gibi | sean-k-mooney: yeah evac is implement the way you describe | |
| 15:42:33 | sean-k-mooney | we talked about chaging htat at some point but there was a reaons why it was hard | |
| 15:42:37 | gibi | I'm wondering if it is enough to check if the allocated value does not change to use the swap mode instead of using the current independent allocation mode. I mean from placement API perspective there just not enough information about the intention of the user. | |
| 15:42:55 | gibi | what if at some point we want a swap behavior that also decreases the size | |
| 15:43:12 | dansmith | gibi: I don't think there are multiple different operations are there? | |
| 15:43:17 | dansmith | we're using POST /allocations for both | |
| 15:43:40 | dansmith | and placement is using the same logic regardless of if we're deleting and re-allocating the same provider vs. different ones, AFAIK | |
| 15:44:22 | gibi | yeah, my point is that POST call can be understood both ways (swap or create/delete) even if the total allocated resources does not change in the process | |
| 15:44:23 | dansmith | but yeah that was my point.. if the operation is not further over-subscribing the provider (or maybe not changing the amount at all) it seems reasonable to let it through | |
| 15:44:26 | gibi | so placemetn does not know | |
| 15:44:28 | dansmith | yeah | |
| 15:44:36 | sean-k-mooney | if the set of RPs in the set of allction dont change and the total resouces consuemd dont hcange then we might be able to skip the capastiy check | |
| 15:45:05 | gibi | if nova tells placement it is a swap, then do a swap regardless of the allocation size. but otherwise keep the current behavior of create/delete | |
| 15:45:06 | dansmith | on the one hand, if you have an allocation for X, right now you can't even *decrease* the allocation size to get closer to happy because "closer to happy is still oversubscribed so reject" | |
| 15:45:26 | sean-k-mooney | honestly it would be better to do this in 2 calls | |
| 15:45:43 | dansmith | sean-k-mooney: I don't see how.. two calls seems worse to me | |
| 15:45:49 | sean-k-mooney | 1 call to create the dest allocaotn and a dedicated call to swap the 2 allocations | |
| 15:45:50 | dansmith | gibi: a flag to just skip the consistency check also feels wrong to me | |
| 15:46:08 | dansmith | sean-k-mooney: oh that's not the problem, it's the swap | |
| 15:46:31 | sean-k-mooney | well right now i think we do the swap an creation of the dest allocation in one call | |
| 15:46:33 | gibi | if a flag in the current API is to anti REST then lets have a separate resource explicitly for swapping | |
| 15:46:57 | dansmith | either way, for the purposes of one-time-use devices, can we say this is already a problem that needs to be solved and it'll block cold migrate for OTU but once we fix it, we're good? | |
| 15:47:15 | gibi | yes that is fair to say | |
| 15:47:22 | dansmith | I will commit to fixing both, FWIW | |
| 15:47:31 | sean-k-mooney | i.e. dont we update the allcoation with the instance uuid to the test host RPs and move the exiting allcotions to the migraiton uuid in one call that just "modifies multiple allcotions" | |
| 15:48:16 | dansmith | gibi: I think a flag would be okay if the semantics are "allow equal or less oversubscription to exist after you do this" | |
| 15:48:16 | gibi | sean-k-mooney: we remove the allocation from the instance uuid and add it to the migration uuid in a POST call then we do a scheduling | |
| 15:48:45 | dansmith | right now it is "oversubscription means fail" even if it's the same amount as before | |
| 15:48:57 | gibi | dansmith: if the client explicity call a swap between two consumers placement should just do a swap without extra checks | |
| 15:49:15 | gibi | i.e. keep the API generic | |
| 15:49:20 | dansmith | gibi: well, that's not very RESTful I think | |
| 15:49:20 | sean-k-mooney | if we move the current allction to the migration uuid before we schedule | |
| 15:49:29 | sean-k-mooney | then im a little confused | |
| 15:49:34 | dansmith | gibi: what about a PATCH to just change the consumer uuid? | |
| 15:49:45 | gibi | dansmith: sounds good to me | |
| 15:49:47 | dansmith | (not sure if we can be that fine-grained about it, I'd have to look) | |
| 15:49:59 | sean-k-mooney | because at that point we jus tneed to convert the allcoation candiate abck to an allction with the instance uuid | |
| 15:50:04 | sean-k-mooney | and then elete the miggration uuid | |
| 15:50:11 | sean-k-mooney | so it does not need ot be in one api post | |
| 15:50:34 | gibi | it is really should be a simple operation to update the owner of the allocation (of a full blown swap between two consumers but we don't need that right now) | |
| 15:50:46 | sean-k-mooney | well that you can do | |
| 15:50:49 | gibi | s/of/or/ | |
| 15:50:55 | sean-k-mooney | you can modify the consumer uuid | |
| 15:51:39 | sean-k-mooney | well the consumer but iint the allcotion uuid the instance uuid or migration uuid depending | |
| 15:51:52 | sean-k-mooney | we added consumer_type to the api at some point to track that | |
| 15:52:34 | gibi | I don't think we have a single placement API operation where you can update the consumer uuid without a reallocation (like the POST call we do currently) | |
| 15:53:43 | gibi | dansmith: so for me I don't need a full blown swap operation between any two consumer. I'm OK to have just a PATCH on an existing allocation to update the consumer uuid in it and do nothing else. | |
| 15:54:13 | sean-k-mooney | this is the existing api we are talking about yes https://docs.openstack.org/api-ref/placement/#update-allocations | |
| 15:54:18 | dansmith | gibi: yeah if we can do that cleanly that might be good.. I'll have to start digging in to determine, but yeah | |
| 15:54:49 | dansmith | are you thinking PATCH /allocations/uuid1 with {consume_uuid: uuid2} ? | |
| 15:55:05 | dansmith | that will work, not sure how the REST police feel, but I'd think it's better than a POST /swap_action | |
| 15:55:16 | gibi | sean-k-mooney: we are talking about https://github.com/openstack/nova/blob/master/nova/scheduler/client/report.py#L2059 that is what we do today | |
| 15:55:50 | gibi | dansmith: yeah lets ask the REST gods about it but the PATCH feels simple to me | |
| 15:55:57 | dansmith | ack | |
| 15:56:09 | sean-k-mooney | patch is an update to an exiting resouce | |
| 15:56:22 | sean-k-mooney | the resouce is keyd by the consumer_uuid /allocations/{consumer_uuid} | |
| 15:56:41 | sean-k-mooney | we could supprot patch to chagne that | |
| 15:56:50 | sean-k-mooney | wihtout conflicting with the existing put | |
| 15:57:25 | sean-k-mooney | but it feesl a littel od ot do /allocations/{instance_uuid} bode: consumer_uuid=<migration uuuid> | |
| 15:57:27 | gibi | yeah we need to change the "key" that is why it feels problematic from REST perspective | |
| 15:57:32 | bauzas | I started to pay attention to this channel but I failed getting the problem to solve | |
| 15:57:40 | sean-k-mooney | i dont hate it | |
| 15:57:51 | bauzas | can someone summarize me the thread ? | |
| 15:58:12 | sean-k-mooney | the ohter option is somthign liek /allocations/{old uuid}/swap/{new uuid} | |
| 15:58:20 | dansmith | bauzas: https://bugs.launchpad.net/nova/+bug/1943191 | |
| 15:58:23 | gibi | bauzas: move operations does not work if the source RP is over allocated or allocated and reserved | |
| 15:58:24 | sean-k-mooney | that would be a post i guess | |
| 15:58:37 | dansmith | bauzas: that and several other bugs, plus my OTU spec | |
| 15:59:06 | bauzas | I see | |
| 16:00:14 | sean-k-mooney | gibi: i think if we document things properly iether could work i think POST /allocations/{consumer_uuid}/swap/{new_consumer_id} is clear honestly | |
| 16:01:25 | sean-k-mooney | tha twould not have any body | |
| 16:01:46 | sean-k-mooney | so there is no posiblity of changing the allcotin or capsity useage and there for its ok to not do checks | |
| 16:02:21 | sean-k-mooney | if we go with patch we would have to ensure the resouces are not changed as well | |
| 16:07:46 | gibi | yeah I'm not against either the PATCH or the POST //swap/ way | |
| 16:10:07 | sean-k-mooney | i think we can all agree that if it alllow us to finally resovle thos bugs in nova either approch is better then what we have today. so if that the direction we head in im fine with say lets define that in the placement api spec | |
| 16:13:11 | gibi | I agree | |
| 16:14:01 | dansmith | yup | |
| 17:06:15 | melwitt | sean-k-mooney: not sure what you'll think of this but I uploaded a patch in regard to the oslo.limit endpoint discovery https://review.opendev.org/c/openstack/nova/+/943507 fyi | |
| 17:17:52 | sean-k-mooney | so we remove the end point check since oslo limists will do that for use internally | |
| 17:18:44 | sean-k-mooney | and we repalce the end point fuction with one that returns the limits for this service/region | |
| 17:19:26 | sean-k-mooney | these are the global limits right not the project specific ones | |
| 17:21:25 | sean-k-mooney | melwitt: without properly loadign context and looking at oslo limits its seams reasonable at first glance | |
| 17:23:50 | melwitt | sean-k-mooney: yeah the thing I think is controversial is the private attributes access | |
| 17:24:08 | sean-k-mooney | that not required with the latest version of oslo.limits right | |
| 17:24:09 | melwitt | maybe in parallel propose some public accesses in oslo.limit and update it when available? dunno | |
| 17:25:19 | sean-k-mooney | https://review.opendev.org/c/openstack/oslo.limit/+/914783/3/oslo_limit/limit.py | |
| 17:26:46 | melwitt | what is there currently will work for both old and new versions | |
| 17:27:09 | melwitt | and underneath oslo.limit will do what it needs to | |
| 17:27:10 | sean-k-mooney | right in the new version we can just call get_registered_limits | |
| 17:27:13 | sean-k-mooney | on the enforcer | |
| 17:27:48 | sean-k-mooney | https://github.com/openstack/oslo.limit/blob/8ada297e6a82f7e50bf746453b8dd21716743798/oslo_limit/limit.py#L183 | |
| 17:29:43 | sean-k-mooney | melwitt: do you need to use the connection today | |
| 17:30:50 | sean-k-mooney | oh that funciton takes a set of resouces to check | |
| 17:33:25 | melwitt | sean-k-mooney: yeah I do that because I want to pull all the resourcs limits in one API call. oslo.limiit does them one API call per resource | |
| 17:34:07 | sean-k-mooney | it sound like we shoudl add a funciton to oslo limits to do that | |