[openstack-dev] [ironic] ironic and traits
Eric Fried
openstack at fried.cc
Mon Oct 23 12:54:13 UTC 2017
I agree with Sean. In general terms:
* A resource provider should be marked with a trait if that feature
* Can be turned on or off (whether it's currently on or not); or
* Is always on and can't ever be turned off.
* A consumer wanting that feature present (doesn't matter whether it's
on or off) should specify it as a required *trait*.
* A consumer wanting that feature present and turned on should
* Specify it as a required trait; AND
* Indicate that it be turned on via some other mechanism (e.g. a
separate extra_spec).
I believe this satisfies Dmitry's (Ironic's) needs, but also Jay's drive
for placement purity.
Please invite me to the hangout or whatever.
Thanks,
Eric
On 10/23/2017 07:22 AM, Mooney, Sean K wrote:
>
>
>
>
> *From:*Jay Pipes [mailto:jaypipes at gmail.com]
> *Sent:* Monday, October 23, 2017 12:20 PM
> *To:* OpenStack Development Mailing List <openstack-dev at lists.openstack.org>
> *Subject:* Re: [openstack-dev] [ironic] ironic and traits
>
>
>
> Writing from my phone... May I ask that before you proceed with any plan
> that uses traits for state information that we have a hangout or
> videoconference to discuss this? Unfortunately today and tomorrow I'm
> not able to do a hangout but I can do one on Wednesday any time of the day.
>
>
>
> */[Mooney, Sean K] on the uefi boot topic I did bring up at the ptg that
> we wanted to standardizes tratis for “verified boot” /*
>
> */that included a trait for uefi secure boot enabled and to indicated a
> hardware root of trust, e.g. intel boot guard or similar/*
>
> */we distinctly wanted to be able to tag nova compute hosts with those
> new traits so we could require that vms that request/*
>
> */a host with uefi secure boot enabled and a hardware root of trust are
> scheduled only to those nodes. /*
>
> */ /*
>
> */There are many other examples that effect both vms and bare metal such
> as, ecc/interleaved memory, cluster on die, /*
>
> */l3 cache code and data prioritization, vt-d/vt-c, HPET, Hyper
> threading, power states … all of these feature may be present on the
> platform/*
>
> */but I also need to know if they are turned on. Ruling out state in
> traits means all of this logic will eventually get pushed to scheduler
> filters/*
>
> */which will be suboptimal long term as more state is tracked. Software
> defined infrastructure may be the future but hardware defined software/*
>
> */is sadly the present…/*
>
> */ /*
>
> */I do however think there should be a sperateion between asking for a
> host that provides x with a trait and asking for x to be configure via/*
>
> */A trait. The trait secure_boot_enabled should never result in the
> feature being enabled It should just find a host with it on. If you want/*
>
> */To request it to be turned on you would request a host with
> secure_boot_capable as a trait and have a flavor extra spec or image
> property to request/*
>
> */Ironic to enabled it. these are two very different request and should
> not be treated the same. /*
>
>
>
>
>
> Lemme know!
>
> -jay
>
>
>
> On Oct 23, 2017 5:01 AM, "Dmitry Tantsur" <dtantsur at redhat.com
> <mailto:dtantsur at redhat.com>> wrote:
>
> Hi Jay!
>
> I appreciate your comments, but I think you're approaching the
> problem from purely VM point of view. Things simply don't work the
> same way in bare metal, at least not if we want to provide the same
> user experience.
>
>
>
> On Sun, Oct 22, 2017 at 2:25 PM, Jay Pipes <jaypipes at gmail.com
> <mailto:jaypipes at gmail.com>> wrote:
>
> Sorry for delay, took a week off before starting a new job.
> Comments inline.
>
> On 10/16/2017 12:24 PM, Dmitry Tantsur wrote:
>
> Hi all,
>
> I promised John to dump my thoughts on traits to the ML, so
> here we go :)
>
> I see two roles of traits (or kinds of traits) for bare metal:
> 1. traits that say what the node can do already (e.g. "the
> node is
> doing UEFI boot")
> 2. traits that say what the node can be *configured* to do
> (e.g. "the node can
> boot in UEFI mode")
>
>
> There's only one role for traits. #2 above. #1 is state
> information. Traits are not for state information. Traits are
> only for communicating capabilities of a resource provider
> (baremetal node).
>
>
>
> These are not different, that's what I'm talking about here. No
> users care about the difference between "this node was put in UEFI
> mode by an operator in advance", "this node was put in UEFI mode by
> an ironic driver on demand" and "this node is always in UEFI mode,
> because it's AARCH64 and it does not have BIOS". These situation
> produce the same result (the node is booted in UEFI mode), and thus
> it's up to ironic to hide this difference.
>
>
>
> My suggestion with traits is one way to do it, I'm not sure what you
> suggest though.
>
>
>
>
> For example, let's say we add the following to the os-traits
> library [1]
>
> * STORAGE_RAID_0
> * STORAGE_RAID_1
> * STORAGE_RAID_5
> * STORAGE_RAID_6
> * STORAGE_RAID_10
>
> The Ironic administrator would add all RAID-related traits to
> the baremetal nodes that had the *capability* of supporting that
> particular RAID setup [2]
>
> When provisioned, the baremetal node would either have RAID
> configured in a certain level or not configured at all.
>
>
> A very important note: the Placement API and Nova scheduler (or
> future Ironic scheduler) doesn't care about this. At all. I know
> it sounds like I'm being callous, but I'm not. Placement and
> scheduling doesn't care about the state of things. It only cares
> about the capabilities of target destinations. That's it.
>
>
>
> Yes, because VMs always start with a clean state, and hypervisor is
> there to ensure that. We don't have this luxury in ironic :) E.g.
> our SNMP driver is not even aware of boot modes (or RAID, or BIOS
> configuration), which does not mean that a node using it cannot be
> in UEFI mode (have a RAID or BIOS pre-configured, etc, etc).
>
>
>
>
>
> This seems confusing, but it's actually very useful. Say, I
> have a flavor that
> requests UEFI boot via a trait. It will match both the nodes
> that are already in
> UEFI mode, as well as nodes that can be put in UEFI mode.
>
>
> No :) It will only match nodes that have the UEFI capability.
> The set of providers that have the ability to be booted via UEFI
> is *always* a superset of the set of providers that *have been
> booted via UEFI*. Placement and scheduling decisions only care
> about that superset -- the providers with a particular capability.
>
>
>
> Well, no, it will. Again, you're purely basing on the VM idea, where
> a VM is always *put* in UEFI mode, no matter how the hypervisor
> looks like. It is simply not the case for us. You have to care what
> state the node is, because many drivers cannot change this state.
>
>
>
>
>
> This idea goes further with deploy templates (new concept
> we've been thinking
> about). A flavor can request something like CUSTOM_RAID_5,
> and it will match the
> nodes that already have RAID 5, or, more interestingly, the
> nodes on which we
> can build RAID 5 before deployment. The UEFI example above
> can be treated in a
> similar way.
>
> This ends up with two sources of knowledge about traits in
> ironic:
> 1. Operators setting something they know about hardware
> ("this node is in UEFI
> mode"),
> 2. Ironic drivers reporting something they
> 2.1. know about hardware ("this node is in UEFI mode" -
> again)
> 2.2. can do about hardware ("I can put this node in UEFI
> mode")
>
>
> You're correct that both pieces of information are important.
> However, only the "can do about hardware" part is relevant to
> Placement and Nova.
>
> For case #1 we are planning on a new CRUD API to set/unset
> traits for a node.
>
>
> I would *strongly* advise against this. Traits are not for state
> information.
>
> Instead, consider having a DB (or JSON) schema that lists state
> information in fields that are explicitly for that state
> information.
>
> For example, a schema that looks like this:
>
> {
> "boot": {
> "mode": <one of 'bios' or 'uefi'>,
> "params": <dict>
> },
> "disk": {
> "raid": {
> "level": <int>,
> "controller": <one of 'sw' or 'hw'>,
> "driver": <string>,
> "params": <dict>
> }, ...
> },
> "network": {
> ...
> }
> }
>
> etc, etc.
>
> Don't use trait strings to represent state information.
>
>
>
> I don't see an alternative proposal that will satisfy what we have
> to solve.
>
>
>
>
> Best,
> -jay
>
> Case #2 is more interesting. We have two options, I think:
>
> a) Operators still set traits on nodes, drivers are simply
> validating them. E.g.
> an operators sets CUSTOM_RAID_5, and the node's RAID
> interface checks if it is
> possible to do. The downside is obvious - with a lot of
> deploy templates
> available it can be a lot of manual work.
>
> b) Drivers report the traits, and they get somehow added to
> the traits provided
> by an operator. Technically, there are sub-cases again:
> b.1) The new traits API returns a union of
> operator-provided and
> driver-provided traits
> b.2) The new traits API returns only operator-provided
> traits; driver-provided
> traits are returned e.g. via a new field
> (node.driver_traits). Then nova will
> have to merge the lists itself.
>
> My personal favorite is the last option: I'd like a clear
> distinction between
> different "sources" of traits, but I'd also like to reduce
> manual work for
> operators.
>
> A valid counter-argument is: what if an operator wants to
> override a
> driver-provided trait? E.g. a node can do RAID 5, but I
> don't want this
> particular node to do it for any reason. I'm not sure if
> it's a valid case, and
> what to do about it.
>
> Let me know what you think.
>
> Dmitry
>
>
> [1] http://git.openstack.org/cgit/openstack/os-traits/tree/
> [2] Based on how many attached disks the node had, the presence
> and abilities of a hardware RAID controller, etc
>
>
>
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