← Back to team overview

openstack team mailing list archive

Re: Allowing clients to pass capability requests through tags?

 

Phew.

I was thinking this was going to be an overloaded capability on the zone name.

Carry on. Nothing to see here.

-S


________________________________________
From: Eric Day [eday@xxxxxxxxxxxx]
Sent: Friday, February 11, 2011 1:36 PM
To: Sandy Walsh
Cc: Justin Santa Barbara; openstack@xxxxxxxxxxxxxxxxxxx; Devin Carlen
Subject: Re: [Openstack] Allowing clients to pass capability requests through tags?

Hi Sandy,

I agree with using tags for full scheduler selection, it's something
I've been pushing for from the start. The request contains any number
of k/v pairs, the services provide any number of k/v pairs, and the
scheduler performs a match (some required, some optional, ...). I see
the URI/zone as one of those tags, not something we need to overload
to contain all of the capabilities. It should only be a hierarchical
"location", which may be geographic location, organizational location
(dept, ...), or some other type (however you decide to construct
your zones).

For example, imagine a dynamic del.icio.us tag that allowed for domain
name filtering on bookmarks (give me all bookmarks with tags [book
review] [domain:slashdot.org]). For Nova, this means issuing requests
like "create instance with [GPU] [Fast disk] [zone:dc1.example.com]".

The important thing is that this is not a tag specific to a particular
service. For example, Swift would never care or need to understand a
'GPU' tag, but it can share and understand zone tags.

-Eric

On Fri, Feb 11, 2011 at 12:40:44PM +0000, Sandy Walsh wrote:
> Heh, hate to be the one to bust up the URI love-fest :)
>
> The issue I have with a single URI being used as the heuristic for node selection is that it is very rigid.
>
> Different business units have different views on the network:
> * Operations may view it as geography/data centers.
> * Consumers may view it as technical ability (gpu's, fast disk, good inter-server speed, etc)
> * Sales/marketing may view it as the number of martinis they can buy ;)
>
> Trees become unmanageable/hard to visualize for users beyond a couple hundred nodes. We are lucky that our geographical/DC-based hierarchy is relatively flat. This is why I was initially pushing for a tag-based system for selection (aka Zone/Host Capabilities).
>
> Consider the way delicio.us works. They manage many millions of URL's and tags are an effective way to slice & dice your way through the data:
> "Show me all the URL's on [OpenStack] [Python] [Zones] [Scheduler]" ... blam.
>
> This is also the way the old Trader services worked:
> "I want a [wax transfer] [color] printer that can has [30ppm] and [300dpi] on [Floor 2]"
>
> "Near" simply has to mean the distance in zones from the most-optimal zones, based on the tags.
>
> "I want a new instance with [GPU] and [Fast Disk] [Good inter-instance network speed] [near] [DRW] [DC1]"
> * where "[near]" implies "as close as possible to" in zone distance.
>
> Personally I don't like overloading the zone name to have a "meaningful" URI when we can get the same functionality with Capabilities/Tags already. And we already know we need Capability support anyway. Especially if it means enforcing a rigid hierarchy.
>
> $0.02
>
> -S
>
>
>
> ________________________________________
> From: openstack-bounces+sandy.walsh=rackspace.com@xxxxxxxxxxxxxxxxxxx [openstack-bounces+sandy.walsh=rackspace.com@xxxxxxxxxxxxxxxxxxx] on behalf of Eric Day [eday@xxxxxxxxxxxx]
> Sent: Friday, February 11, 2011 4:30 AM
> To: Justin Santa Barbara
> Cc: openstack@xxxxxxxxxxxxxxxxxxx; Devin Carlen
> Subject: Re: [Openstack] Allowing clients to pass capability requests through tags?
>
> The main reason I was proposing full location/zone of objects is to
> allow this type of 'near' scheduling to happen without understanding
> what the actual object is. For example, imagine we want to start an
> instance near a particular swift object. We could query the swift
> object and in the metadata there could be a 'zone' tag (well, three,
> one for each copy). For example:
>
> get swift-12345: zone=rack12.room2.dc1.dfw.rackspace.com
>
> I can now use that zone name to:
>
> create_instance: openstack:near=rack12.room2.dc1.dfw.rackspace.com
>
> The deployment can decide what 'near' is (perhaps a measure of link
> speed or latency). This way a particular deployment that uses the
> same URI/zone names across projects can account for locality without
> knowing what objects from different services are. If it were just
> 'near=swift-12345', it would need to understand what a swift object
> was and perform that lookup to find out where it is.
>
> So you can still grab a zone tag from a volume you created:
>
> get vol-000001: rack4.room2.dc1.dfw.rackspace.com
>
> and use the zone to launch an instance with:
>
> create_instance: openstack:near=rack4.room2.dc1.dfw.rackspace.com
>
> We can also write schedulers/tools for a particular deployment
> that understands the zones to just say 'always prefer in
> dc1.dfw.rackspace.com', because power is cheaper there right now, or
> 'test.dc1.dfw.rackspace.com' because that is my test zone (perhaps
> only enabled for certain accounts in the scheduler too).
>
> -Eric
>
> On Thu, Feb 10, 2011 at 03:38:42PM -0800, Justin Santa Barbara wrote:
> >    I think the blueprint was largely complementary to the multi-zone stuff;
> >    this is more about how the client _requests_ a particular
> >    location/capability through the API.  The multi-zone blueprint seems to be
> >    more about how nova would satisfy those requests (in a non-trivial zone
> >    structure.)
> >    The root motivator is indeed getting a 'good' connection to a storage
> >    volume.  I'm thinking of iSCSI SAN storage here, so in my case this
> >    probably means the SAN device with the least number of switches in
> >    between.  There could well be SAN devices in each rack (e.g. Solaris
> >    volume nodes), or the devices could even be running on the host nodes, and
> >    I don't believe that zones in the EC2 sense are sufficient here.
> >    But I guess that if the zone hierarchy went all the way down to the rack
> >    (or machine), that would work.  So I could create a volume and it would
> >    come back with a location of "rack4.room2.dc1.dfw.rackspace.com" and I
> >    could then request allocation of machines in that same rack?  Is that the
> >    vision of the nested zones?
> >    I do have a concern that long-term if we _only_ use zones, that's trying
> >    to multiplex a lot of information into the zone hierarchy, and we can
> >    really only put one attribute in there.  I also like the flexibility of
> >    the 'openstack:near=vol-000001' request, because then the cloud can decide
> >    how near to place the instance based on its knowledge of the topology, and
> >    the clients can be oblivious to the storage system and arrangement.  But,
> >    my immediate requirement would indeed be satisfied if the zones went down
> >    to the rack/machine level.
> >    An alternative way to look at zones and instance-types is that they're
> >    actually just fail-if-not-satisfiable tags of the creation request
> >    (openstack:+zone=us-east-1a and openstack:+instancetype=m1.large)  They're
> >    only distinguished attributes because AWS doesn't have an
> >    extensibility mechanism, which this blueprint would give us.
> >    Justin
> >
> >    On Thu, Feb 10, 2011 at 3:12 PM, Devin Carlen <devcamcar@xxxxxx> wrote:
> >
> >      I haven't totally digested this blueprint yet but it seems like there is
> >      some overlap with what is being discussed with the multi zone metadata
> >      stuff.  One approach might be to handle this awt the scheduler level
> >      though and try to ensure things are always in the same zone when
> >      appropriate.
> >      I think the bigger question you raise is how to request local volumes
> >      when possible, yes?
> >
> >      Devin
> >      On Feb 10, 2011, at 3:37 PM, Justin Santa Barbara <justin@xxxxxxxxxxxx>
> >      wrote:
> >
> >        Does anyone have any thoughts/objections on the blueprint I posted for
> >        allowing clients to pass capability-requests through tags?  I'm
> >        planning on starting implementation soon, so if people think this is a
> >        bad idea I'd rather know before I start coding!
> >        Blueprint: https://blueprints.launchpad.net/nova/+spec/use-metadata-tags-for-capabilities
> >        Wiki: https://blueprints.launchpad.net/nova/+spec/use-metadata-tags-for-capabilities
> >        And a quick TLDR:
> >        API clients need a way to request e.g. placement of machines near each
> >        other / near volumes, or that a volume be created with a particular
> >        RAID level, or that a machine be created in a HIPAA compliant
> >        environment.  (This is complementary to the work on hierarchical zones
> >        & URL naming, I believe)
> >        I propose using the instance tags for this, e.g. specifying
> >        openstack:near=vol-000001 when creating an instance to request
> >        locating the instance 'close to' that volume.
> >        By default these requests would be best-effort and ignored-if-unknown;
> >        if the client wants to specify that something is required and should
> >        fail if not understood or not satisfiable, they could use a "+" e.g.
> >        openstack:+location=*.dc1.north.rackspace.com
> >        Controversially (?), this would not be supported for clients using the
> >        AWS API, because tags can only be specified once the instance has
> >        already been created.
> >        Feedback appreciated!
> >        Justin
> >
> >        _______________________________________________
> >        Mailing list: https://launchpad.net/~openstack
> >        Post to     : openstack@xxxxxxxxxxxxxxxxxxx
> >        Unsubscribe : https://launchpad.net/~openstack
> >        More help   : https://help.launchpad.net/ListHelp
>
> > _______________________________________________
> > Mailing list: https://launchpad.net/~openstack
> > Post to     : openstack@xxxxxxxxxxxxxxxxxxx
> > Unsubscribe : https://launchpad.net/~openstack
> > More help   : https://help.launchpad.net/ListHelp
>
>
> _______________________________________________
> Mailing list: https://launchpad.net/~openstack
> Post to     : openstack@xxxxxxxxxxxxxxxxxxx
> Unsubscribe : https://launchpad.net/~openstack
> More help   : https://help.launchpad.net/ListHelp
>
>
> Confidentiality Notice: This e-mail message (including any attached or
> embedded documents) is intended for the exclusive and confidential use of the
> individual or entity to which this message is addressed, and unless otherwise
> expressly indicated, is confidential and privileged information of Rackspace.
> Any dissemination, distribution or copying of the enclosed material is prohibited.
> If you receive this transmission in error, please notify us immediately by e-mail
> at abuse@xxxxxxxxxxxxx, and delete the original message.
> Your cooperation is appreciated.


Confidentiality Notice: This e-mail message (including any attached or
embedded documents) is intended for the exclusive and confidential use of the
individual or entity to which this message is addressed, and unless otherwise
expressly indicated, is confidential and privileged information of Rackspace. 
Any dissemination, distribution or copying of the enclosed material is prohibited.
If you receive this transmission in error, please notify us immediately by e-mail
at abuse@xxxxxxxxxxxxx, and delete the original message. 
Your cooperation is appreciated.




References