Earlier  
Later
New Search
Posted Nick Remark
#openstack-nova - 2022-09-01
15:23:55 dansmith well, I like playing with guns, but maybe.. playing with fire? :)
15:24:00 bauzas if we try to update a configdrive and this doesn't work, then our user won't be happy at all
15:24:28 bauzas dansmith: what you prefer
15:24:32 bauzas or playing with teslas
15:25:06 dansmith as long as you mean "teslas, the unit of charge, meaning playing with dangerous high-voltage" .. then sure :D
15:25:15 bauzas point is, we need to only accept to update the userdata if the configdriver correctly regenerated
15:25:18 sean-k-mooney https://github.com/openstack/nova/blob/master/nova/virt/ironic/driver.py#L1060-L1092
15:25:28 sean-k-mooney so ironci jsut tuns it into a string yes
15:25:48 bauzas dansmith: like "driving a tesla with a 10% battery for 100km"
15:25:55 dansmith oh I see
15:26:02 dansmith that *is* scary :)
15:26:10 bauzas this *may* work
15:26:19 bauzas but before driving, you need to ensure you can do it
15:26:34 bauzas the same goes with configdrives
15:26:50 sean-k-mooney and they pass it in spawn and rebuild https://github.com/openstack/nova/blob/bcdf5988f6ae902dba9b41144a7b4a60688b627c/nova/virt/ironic/driver.py#L1189-L1191
15:26:54 bauzas you only accept the userdata to be updated once you're sure your configdrive is correctly regenerated
15:27:12 dansmith so the feeling I'm getting here is that there are a lot of open questions at this point
15:27:19 bauzas since the user doesn't have an idea whether the userdata is updated and only relies on the fact he/she restarted the instance
15:27:32 sean-k-mooney bauzas: well that is already a problem today
15:27:40 dansmith sean-k-mooney: no it's not
15:27:45 bauzas today the userdata is immutable
15:27:53 dansmith sean-k-mooney: if you can only provide userdata during create, it's clear what userdata the instance sees
15:28:03 bauzas that reminds me the discussions we had when reviewing server groups /PUT
15:28:06 sean-k-mooney it is the config drive is not updated today if you atach interface or volumes or update the server metadta
15:28:10 sean-k-mooney the user data is not statble
15:28:16 sean-k-mooney btu in general the config drive can be
15:28:34 dansmith configdrive != userdata
15:28:43 sean-k-mooney yep that is my point
15:28:51 sean-k-mooney the config drive can be stale today the user data is not
15:29:00 sean-k-mooney but that is only because its imutable
15:29:08 dansmith right
15:29:12 dansmith not ideal, but also not ambiguous
15:29:15 dansmith which is bauzas' point I think
15:29:18 bauzas yup
15:29:31 bauzas since it's immutable, this isn't a problem
15:29:36 sean-k-mooney sure but its expected that the user data script will likely depend on the other datta in the config drive
15:29:57 sean-k-mooney specificly the device role taggin info
15:29:59 opendevreview Dan Smith proposed openstack/nova master: WIP: Add recreate_configdrive to reboot https://review.opendev.org/c/openstack/nova/+/855529
15:30:12 dansmith sean-k-mooney: here's the rpc stuff ^ passing tests, not wired into anything else
15:30:20 dansmith just so it's available
15:30:30 sean-k-mooney dansmith: but to your point it does sound like there is enough stuff that we wont have this mergable even with an FFE
15:30:32 dansmith needs more test coverage and an assert on soft I think
15:33:04 bauzas sean-k-mooney: my personal opinion is that the more I review this API change, the more I think I discover points we missed
15:33:10 bauzas hence my concern
15:33:15 dansmith so I should probably rebase that on your regen configdrive patch and I guess I can rebase the api bit on top of that and trivially wire it up
15:33:59 bauzas the configdrive regeneration is already a concern (making sure we validate it synchronously with the userdata update)
15:34:13 bauzas the fact that we leave other virt drivers in the weeds is another concern
15:34:21 bauzas both weren't discussed at the PTG
15:34:46 dansmith so on that,
15:34:53 bauzas and when I reviewed the spec, I was letting enough comments explaining how I was thinking the reboot solution was fragile
15:34:59 dansmith are we really expecting anyone to update vmware or hyperv to do this?
15:35:05 bauzas reasonably not
15:35:10 dansmith ironic perhaps, but for the above patch,
15:35:19 dansmith I was looking at those other drivers and wondering when they were last touched
15:35:35 bauzas surely, but we haven't even asked them to look
15:35:53 dansmith okay I guess we've had changes in 2022 for vmware
15:35:58 dansmith so maybe doable
15:36:31 dansmith not much for hyperv though
15:37:18 dansmith so I don't see any configdrive stuff in hyperv at first glance
15:37:48 bauzas fair enough, but then question
15:37:54 bauzas I'm an user
15:38:09 bauzas I wanna update my pet's userdata
15:38:13 bauzas I do it
15:38:33 bauzas and then I don't understand, my f*** script doesn't run as expected when I restart the guest
15:38:44 bauzas shall I open a ticket ?
15:39:08 dansmith oh it's in hyperv, just in vmops.py
15:39:24 bauzas oh, simple, your cloud was running some driver on that host that was having trouble with updating the configdrive
15:39:35 bauzas either because it was a legacy driver
15:39:44 bauzas or because something (like a perm error) expected
15:40:10 bauzas honestly, this spec was just about touching an internal Nova DB record
15:40:21 bauzas now, we're pulling way more than that
15:40:47 dansmith yeah, it's becoming more about configdrive than anything else
15:41:27 sean-k-mooney bauzas: in two converstaion but form my persepcitve i dont think we really have discoverd anythign bar the rpc change. i reveiw the spec with the understandin it was scoped to libvirt
15:42:44 bauzas yet again, can't we just assume to update instance's metadata only if not configdrive-driven, and leave people who care about configdrives deal with the complexity one day or another?
15:42:45 dansmith I dunno, I can see the argument for this being scoped to just one driver, but for something this fundamental it seems pretty unfortunate to say it's only for libvirt
15:43:10 bauzas I'm pretty sure we wouldn't have this back-to-back
15:44:31 dansmith so we reject the api call if configdrive=True always?
15:44:57 bauzas that's my question
15:45:10 dansmith doesn't that get closer to your concern on the spec that people think they have updated their instance but didn't reboot it and don't realize that cloud-init doesn't update their stuff?
15:45:29 dansmith I mean, that's just a misunderstanding of cloud-init, but I thought that was your concern
15:45:36 dansmith anyway, I dunno
15:45:37 bauzas if the update failed, they know the instance userdata wasn't updated
15:46:53 bauzas they would know this was because configdriver if they asked by boot params
15:47:15 bauzas but they wouldn't know if the clould defaulted to force configdrives or if the image was asking for it
15:47:22 dansmith right, it's not always their choice
15:47:45 bauzas anyway, I'm just offering a trade-off because I'm not really happy with the current state of the series
15:48:22 bauzas also, is the owner of the patch around ?
15:48:29 bauzas or are we offering our help for free ?
15:48:47 dansmith who is asking for this btw?
15:48:59 dansmith aside from the author
15:49:02 bauzas a private clould company
15:49:06 bauzas Inovex
15:49:07 jhartkopf I'm here
15:49:17 bauzas cool, glad to hear you jhartkopf
15:49:24 bauzas jhartkopf: lemme summarize
15:49:25 dansmith jhartkopf: do you care about the configdrive case?
15:49:37 bauzas we're having a problem with https://review.opendev.org/c/openstack/nova/+/816157/16
15:49:45 bauzas and we don't know how to move forward
15:50:02 jhartkopf yep I quickly read your discussion
15:50:03 bauzas there is a proposed solution, but this is premature work and we're very late in the cycle

Earlier   Later