| Posted | Nick | Remark | |
|---|---|---|---|
| #openstack-nova - 2017-04-26 | |||
| 16:02:36 | sfinucan | right? | |
| 16:02:39 | mriedem | but we didn't want to go the route of stuffing bdm information in flavor extra specs | |
| 16:02:44 | mriedem | the worst of both worlds | |
| 16:03:22 | johnthetubaguy | mriedem: the above spec is the reverse I thought, its just a flavor that says "must have boot volume" | |
| 16:04:00 | mriedem | johnthetubaguy: the UX was bad imo, | |
| 16:04:10 | mriedem | i think the idea was you mark your flavors as local_disks=False, | |
| 16:04:25 | mriedem | and if the user tries to create a server with one of those flavors but without defining bdms, it fails | |
| 16:04:41 | johnthetubaguy | sfinucan: my head swap was in MiB in the flavor but it seems like its not, I must have got mixed up with RAM | |
| 16:05:00 | mriedem | putting the burden on the user to have to sort out which flavors they can use and if they have to have volumes, etc | |
| 16:05:19 | mriedem | it'd be much better UX if the operator configures the compute to use cinder as an ephemeral storage backend | |
| 16:05:25 | mriedem | regardless of flavor | |
| 16:05:33 | bauzas | oh fun, we already verify existing allocations before posting | |
| 16:05:45 | bauzas | mriedem: jaypipes: dansmith: cdent: ^ | |
| 16:06:10 | cdent | yes, didn't we already know that? | |
| 16:06:12 | johnthetubaguy | mriedem: true, but that seems years away at this point, and the other way makes diskless hypervisors upstream | |
| 16:06:22 | bauzas | cdent: I wrote that as a work item | |
| 16:06:30 | bauzas | for the scheduler claims stuff | |
| 16:06:34 | mriedem | johnthetubaguy: well, https://specs.openstack.org/openstack/nova-specs/specs/newton/approved/flavor-root-disk-none.html also bakes that into the API | |
| 16:06:36 | johnthetubaguy | mriedem: the problem is the mix of diskless and non-diskless | |
| 16:06:40 | bauzas | cdent: and nobody reviewed that saying "meh" :p | |
| 16:06:56 | mriedem | johnthetubaguy: so then we have to support local_disks=False in flavors in the API for years probably | |
| 16:07:03 | mriedem | even if we ever get cinder ephemeral | |
| 16:07:08 | cdent | bauzas: well, I think I did when discussing the change to not use RPC, but it didn't get picked up and didn't seem a relevant detail | |
| 16:07:34 | mriedem | johnthetubaguy: there was also https://review.openstack.org/#/c/432503/ which i really didn't want since it mixes extra specs and bdms | |
| 16:07:46 | cdent | bauzas: in any case, did you seem my earlier [t 3xBS] | |
| 16:07:47 | purplerbot | <cdent> bauzas: left a comment on your WIP that I wanted to be sure you didn't miss since your -W [2017-04-26 15:52:17.085960] [n 3xBS] | |
| 16:07:56 | johnthetubaguy | mriedem: yeah, the auto create seems evil | |
| 16:08:21 | mriedem | johnthetubaguy: anyway, we talked about cinder ephemeral at the ptg, a spec was never written, but it's a forum session to discuss it or alternatives | |
| 16:08:30 | johnthetubaguy | mriedem: yeah | |
| 16:08:36 | mriedem | if people want this, then they need to put up the dev resources to do it | |
| 16:08:41 | mriedem | rather than api hacks | |
| 16:09:09 | mriedem | cinder ephemeral imagebackend also allows us to deprecate lvm, rbd and scaleio (if that lands) | |
| 16:09:29 | mriedem | i think anyway | |
| 16:09:57 | johnthetubaguy | mriedem: my problem is the whole way we do disks is truly terrible, so to get to something clean buts a lot of burden on the users to switch to something radically different | |
| 16:10:00 | mriedem | having said this, there is probably a world of API operations that don't work for boot from volume servers, like shelve/unshelve and rebuild | |
| 16:10:23 | mriedem | users == operators? | |
| 16:10:28 | johnthetubaguy | mriedem: they should all work, they might be broken | |
| 16:10:33 | johnthetubaguy | mriedem: I was meaning API users | |
| 16:11:06 | mriedem | i don't see how a cinder ephemeral imagebackend is radically different from the API pov | |
| 16:11:11 | mriedem | the api doesn't change | |
| 16:11:30 | mriedem | the operator just says he wants to use cinder for storage on this compute host | |
| 16:11:46 | mriedem | which is what that spec is also doing, probably with host aggregates tied to the marked flavors | |
| 16:11:55 | johnthetubaguy | mriedem: the problem is we create user visible cinder volumes, that we didn't before, then we talk about customizing the volume type, and mixed diskless and non-diskless, and it all gets a bit tricky. | |
| 16:13:30 | mriedem | at the ptg we said that we could add the support for volume type via extra spec if we did cinder ephemeral imagebackend, | |
| 16:13:33 | mriedem | which was a win for cburgess | |
| 16:14:05 | mriedem | i agree you get a user visible cinder volume that you wouldn't have before, | |
| 16:14:17 | edleafe | ` /win 14 | |
| 16:14:20 | mriedem | but i'm not sure that's a huge issue as long as it's marked for delete_on_termination=True | |
| 16:14:21 | cburgess | What do we mean by "wouldn't have before"? | |
| 16:14:34 | mriedem | wouldn't have before "automatically" | |
| 16:14:39 | mriedem | today you opt in to bfv | |
| 16:14:58 | mriedem | this would have nova do it for you depending on which compute host you land on | |
| 16:15:09 | cburgess | OK right but, presumably it would be a deployer, or at least cloud admin, option to use the new as of yet unspeced nova roots on cinder idea. | |
| 16:15:33 | mriedem | yes it would be | |
| 16:15:42 | cburgess | So I don't think its a problem that users would see the cinder volumes. | |
| 16:15:49 | mriedem | as would marking your flavors as local_disks=False like in https://specs.openstack.org/openstack/nova-specs/specs/newton/approved/flavor-root-disk-none.html | |
| 16:15:56 | cburgess | In pure BFV environments today they already deal with that. | |
| 16:16:28 | mriedem | it's just with https://specs.openstack.org/openstack/nova-specs/specs/newton/approved/flavor-root-disk-none.html if the user picks the wrong flavor or makes the wrong server create request, it will blow up | |
| 16:16:36 | mriedem | and then they have to go back and figure out how to add bdms via the nova boot cli | |
| 16:16:37 | cburgess | How so? | |
| 16:16:37 | mriedem | which is not fun | |
| 16:16:40 | cburgess | I'm not following. | |
| 16:16:54 | mriedem | "The use case for End Users is to not create ephemeral (root) disks locally on the hypervisor by accident. When launching an instance from a flavor with disabled local disks, the user will be informed to create a bootable volume in order to launch the instance with that volume." | |
| 16:17:05 | mriedem | "be informed" means 400 | |
| 16:17:45 | mriedem | holy crap, just look at the proposed change minefield | |
| 16:17:47 | mriedem | "error, when flavor create request with local_disks=False and root_gb > 0 and/or emphemeral_gb > 0 and/or swap_gb > 0" | |
| 16:18:02 | mriedem | "return descriptive exception, when flavor with local_disks=False and requested image larger than given blockdevice layout" | |
| 16:18:07 | mriedem | "if local_disks is omitted or set to True, root_gb is mandatory again" | |
| 16:18:22 | mriedem | "if jupiter is aligned with saturn and it's a leap year, the api works, else 400" | |
| 16:18:37 | cburgess | Yeah this seems... sub-optimal. | |
| 16:18:44 | cdent | what about when mercury is in retrograde? | |
| 16:18:53 | cburgess | Why can't we use the rest of the info from the boot request and craft a BFV request for them. | |
| 16:18:59 | mriedem | cdent: then all bets are off | |
| 16:19:16 | mriedem | cburgess: that's probably https://review.openstack.org/#/c/432503/ | |
| 16:19:18 | cburgess | Granted... turning off local disks is a really big deal/issue today and causes us issues. | |
| 16:20:02 | johnthetubaguy | right, its not possible today, due to root_gb=0 meaning "don't resize image" | |
| 16:20:07 | cburgess | mriedem Yeah but you killed that. So it seems to me that if we do local_disk=False we either need to build the BDM under the covers, or we need to allow the BDM in the flavor as well. | |
| 16:20:34 | cburgess | johnthetubaguy How does that impact this exactly? | |
| 16:20:40 | mriedem | if we build the bdm under the coveres if local_disk=False, that's the same thing as https://review.openstack.org/#/c/432503/ | |
| 16:20:45 | mriedem | just a different attribute on the flavor | |
| 16:20:56 | mriedem | ^ was doing is_bdm_flavor=True on the flavor | |
| 16:20:58 | mriedem | same idea | |
| 16:21:01 | cburgess | OK | |
| 16:21:02 | cburgess | Well... | |
| 16:21:08 | johnthetubaguy | cburgess: people often assume 0 GB means no disk | |
| 16:21:20 | cburgess | Honestly it seems reasonable to me. But then I thought that spec was reasonable to begin with. | |
| 16:21:25 | cburgess | johnthetubaguy Well they are wrong :P | |
| 16:21:30 | johnthetubaguy | cburgess: agreed | |
| 16:21:35 | mriedem | cburgess: you're saying you like both ideas | |
| 16:21:45 | mriedem | the abandoned spec, and the extra specs / bfv thing | |
| 16:21:59 | cburgess | mriedem I'm saying disks are a total and complete mess and we have to find ways of making this easier and better to consume because right now the whole thing is a confusing mess. | |
| 16:21:59 | mriedem | cburgess: you like anything that gets rid of your local patches :) | |
| 16:22:33 | cburgess | mriedem Yes.. but... I have those local patches because things are a mess. So I like anything that makes a cleaner, easier to use system for users. | |
| 16:22:48 | mriedem | yeah i know, | |
| 16:23:00 | mriedem | if a cinder ephemeral imagebackend is never going to happen, then maybe we go with https://review.openstack.org/#/c/432503/ | |
| 16:23:14 | mriedem | i just really dislike coupling two terrible tech debt things in nova, extra specs and bdms | |
| 16:23:21 | mriedem | because that's bound to be a maintenance nightmare | |
| 16:23:32 | cburgess | Well I think a cinder ephemeral imagebackend is a long term thing. Question is what, if anything, can we do in a cycle or two. | |
| 16:23:44 | smcginnis | I've been seeing more and more requests for using Cinder as ephemeral storage. | |
| 16:23:57 | mriedem | cburgess: nothing is happening in pike | |