Open Stack

openstack-bounces+mjfork=us.ibm.com at lists.launchpad.net wrote on 08/27/2012
02:58:56 PM:

> From: David Kang <dkang at isi.edu>
> To: Vishvananda Ishaya <vishvananda at gmail.com>,
> Cc: OpenStack Development Mailing List <openstack-
> dev at lists.openstack.org>, "openstack at lists.launchpad.net \
> (openstack at lists.launchpad.net\)" <openstack at lists.launchpad.net>
> Date: 08/27/2012 03:06 PM
> Subject: Re: [Openstack] [openstack-dev] Discussion about where to
> put database for bare-metal provisioning (review 10726)
> Sent by: openstack-bounces+mjfork=us.ibm.com at lists.launchpad.net
>
>
>  Hi Vish,
>
>  I think I understand your idea.
> One service entry with multiple bare-metal compute_node entries are
> registered at the start of bare-metal nova-compute.
> 'hypervisor_hostname' must be different for each bare-metal machine,
> such as 'bare-metal-0001.xxx.com', 'bare-metal-0002.xxx.com', etc.)
> But their IP addresses must be the IP address of bare-metal nova-
> compute, such that an instance is casted
> not to bare-metal machine directly but to bare-metal nova-compute.

I believe the change here is to cast out the message to the
<topic>.<service-hostname>. Existing code sends it to the compute_node
hostname (see line 202 of nova/scheduler/filter_scheduler.py, specifically
host=weighted_host.host_state.host).  Changing that to cast to the service
hostname would send the message to the bare-metal proxy node and should not
have an effect on current deployments since the service hostname and the
host_state.host would always be equal.  This model will also let you keep
the bare-metal compute node IP in the compute node table.

>  One extension we need to do at the scheduler side is using (host,
> hypervisor_hostname) instead of (host) only in host_manager.py.
> 'HostManager.service_state' is { <host> : { <service > : { cap k : v }}}.
> It needs to be changed to { <host> : { <service> : {
> <hypervisor_name> : { cap k : v }}}}.
> Most functions of HostState need to be changed to use (host,
> hypervisor_name) pair to identify a compute node.

Would an alternative here be to change the top level "host" to be the
hypervisor_hostname and enforce uniqueness?

>  Are we on the same page, now?
>
>  Thanks,
>  David
>
> ----- Original Message -----
> > Hi David,
> >
> > I just checked out the code more extensively and I don't see why you
> > need to create a new service entry for each compute_node entry. The
> > code in host_manager to get all host states explicitly gets all
> > compute_node entries. I don't see any reason why multiple compute_node
> > entries can't share the same service. I don't see any place in the
> > scheduler that is grabbing records by "service" instead of by "compute
> > node", but if there is one that I missed, it should be fairly easy to
> > change it.
> >
> > The compute_node record is created in the compute/resource_tracker.py
> > as of a recent commit, so I think the path forward would be to make
> > sure that one of the records is created for each bare metal node by
> > the bare metal compute, perhaps by having multiple resource_trackers.
> >
> > Vish
> >
> > On Aug 27, 2012, at 9:40 AM, David Kang <dkang at isi.edu> wrote:
> >
> > >
> > >  Vish,
> > >
> > >  I think I don't understand your statement fully.
> > > Unless we use different hostnames, (hostname, hypervisor_hostname)
> > > must be the
> > > same for all bare-metal nodes under a bare-metal nova-compute.
> > >
> > >  Could you elaborate the following statement a little bit more?
> > >
> > >> You would just have to use a little more than hostname. Perhaps
> > >> (hostname, hypervisor_hostname) could be used to update the entry?
> > >>
> > >
> > >  Thanks,
> > >  David
> > >
> > >
> > >
> > > ----- Original Message -----
> > >> I would investigate changing the capabilities to key off of
> > >> something
> > >> other than hostname. It looks from the table structure like
> > >> compute_nodes could be have a many-to-one relationship with
> > >> services.
> > >> You would just have to use a little more than hostname. Perhaps
> > >> (hostname, hypervisor_hostname) could be used to update the entry?
> > >>
> > >> Vish
> > >>
> > >> On Aug 24, 2012, at 11:23 AM, David Kang <dkang at isi.edu> wrote:
> > >>
> > >>>
> > >>>  Vish,
> > >>>
> > >>>  I've tested your code and did more testing.
> > >>> There are a couple of problems.
> > >>> 1. host name should be unique. If not, any repetitive updates of
> > >>> new
> > >>> capabilities with the same host name are simply overwritten.
> > >>> 2. We cannot generate arbitrary host names on the fly.
> > >>>   The scheduler (I tested filter scheduler) gets host names from
> > >>>   db.
> > >>>   So, if a host name is not in the 'services' table, it is not
> > >>>   considered by the scheduler at all.
> > >>>
> > >>> So, to make your suggestions possible, nova-compute should
> > >>> register
> > >>> N different host names in 'services' table,
> > >>> and N corresponding entries in 'compute_nodes' table.
> > >>> Here is an example:
> > >>>
> > >>> mysql> select id, host, binary, topic, report_count, disabled,
> > >>> availability_zone from services;
> > >>> +----+-------------+----------------+-----------
> +--------------+----------+-------------------+
> > >>> | id | host | binary | topic | report_count | disabled |
> > >>> | availability_zone |
> > >>> +----+-------------+----------------+-----------
> +--------------+----------+-------------------+
> > >>> |  1 | bespin101 | nova-scheduler | scheduler | 17145 | 0 | nova |
> > >>> |  2 | bespin101 | nova-network | network | 16819 | 0 | nova |
> > >>> |  3 | bespin101-0 | nova-compute | compute | 16405 | 0 | nova |
> > >>> |  4 | bespin101-1 | nova-compute | compute | 1 | 0 | nova |
> > >>> +----+-------------+----------------+-----------
> +--------------+----------+-------------------+
> > >>>
> > >>> mysql> select id, service_id, hypervisor_hostname from
> > >>> compute_nodes;
> > >>> +----+------------+------------------------+
> > >>> | id | service_id | hypervisor_hostname |
> > >>> +----+------------+------------------------+
> > >>> |  1 | 3 | bespin101.east.isi.edu |
> > >>> |  2 | 4 | bespin101.east.isi.edu |
> > >>> +----+------------+------------------------+
> > >>>
> > >>>  Then, nova db (compute_nodes table) has entries of all bare-metal
> > >>>  nodes.
> > >>> What do you think of this approach.
> > >>> Do you have any better approach?
> > >>>
> > >>>  Thanks,
> > >>>  David
> > >>>
> > >>>
> > >>>
> > >>> ----- Original Message -----
> > >>>> To elaborate, something the below. I'm not absolutely sure you
> > >>>> need
> > >>>> to
> > >>>> be able to set service_name and host, but this gives you the
> > >>>> option
> > >>>> to
> > >>>> do so if needed.
> > >>>>
> > >>>> iff --git a/nova/manager.py b/nova/manager.py
> > >>>> index c6711aa..c0f4669 100644
> > >>>> --- a/nova/manager.py
> > >>>> +++ b/nova/manager.py
> > >>>> @@ -217,6 +217,8 @@ class SchedulerDependentManager(Manager):
> > >>>>
> > >>>> def update_service_capabilities(self, capabilities):
> > >>>> """Remember these capabilities to send on next periodic
> > >>>> update."""
> > >>>> + if not isinstance(capabilities, list):
> > >>>> + capabilities = [capabilities]
> > >>>> self.last_capabilities = capabilities
> > >>>>
> > >>>> @periodic_task
> > >>>> @@ -224,5 +226,8 @@ class SchedulerDependentManager(Manager):
> > >>>> """Pass data back to the scheduler at a periodic interval."""
> > >>>> if self.last_capabilities:
> > >>>> LOG.debug(_('Notifying Schedulers of capabilities ...'))
> > >>>> - self.scheduler_rpcapi.update_service_capabilities(context,
> > >>>> - self.service_name, self.host, self.last_capabilities)
> > >>>> + for capability_item in self.last_capabilities:
> > >>>> + name = capability_item.get('service_name', self.service_name)
> > >>>> + host = capability_item.get('host', self.host)
> > >>>> + self.scheduler_rpcapi.update_service_capabilities(context,
> > >>>> + name, host, capability_item)
> > >>>>
> > >>>> On Aug 21, 2012, at 1:28 PM, David Kang <dkang at isi.edu> wrote:
> > >>>>
> > >>>>>
> > >>>>>  Hi Vish,
> > >>>>>
> > >>>>>  We are trying to change our code according to your comment.
> > >>>>> I want to ask a question.
> > >>>>>
> > >>>>>>>> a) modify driver.get_host_stats to be able to return a list
> > >>>>>>>> of
> > >>>>>>>> host
> > >>>>>>>> stats instead of just one. Report the whole list back to the
> > >>>>>>>> scheduler. We could modify the receiving end to accept a list
> > >>>>>>>> as
> > >>>>>>>> well
> > >>>>>>>> or just make multiple calls to
> > >>>>>>>> self.update_service_capabilities(capabilities)
> > >>>>>
> > >>>>>  Modifying driver.get_host_stats to return a list of host stats
> > >>>>>  is
> > >>>>>  easy.
> > >>>>> Calling muliple calls to
> > >>>>> self.update_service_capabilities(capabilities) doesn't seem to
> > >>>>> work,
> > >>>>> because 'capabilities' is overwritten each time.
> > >>>>>
> > >>>>>  Modifying the receiving end to accept a list seems to be easy.
> > >>>>> However, 'capabilities' is assumed to be dictionary by all other
> > >>>>> scheduler routines,
> > >>>>> it looks like that we have to change all of them to handle
> > >>>>> 'capability' as a list of dictionary.
> > >>>>>
> > >>>>>  If my understanding is correct, it would affect many parts of
> > >>>>>  the
> > >>>>>  scheduler.
> > >>>>> Is it what you recommended?
> > >>>>>
> > >>>>>  Thanks,
> > >>>>>  David
> > >>>>>
> > >>>>>
> > >>>>> ----- Original Message -----
> > >>>>>> This was an immediate goal, the bare-metal nova-compute node
> > >>>>>> could
> > >>>>>> keep an internal database, but report capabilities through nova
> > >>>>>> in
> > >>>>>> the
> > >>>>>> common way with the changes below. Then the scheduler wouldn't
> > >>>>>> need
> > >>>>>> access to the bare metal database at all.
> > >>>>>>
> > >>>>>> On Aug 15, 2012, at 4:23 PM, David Kang <dkang at isi.edu> wrote:
> > >>>>>>
> > >>>>>>>
> > >>>>>>> Hi Vish,
> > >>>>>>>
> > >>>>>>> Is this discussion for long-term goal or for this Folsom
> > >>>>>>> release?
> > >>>>>>>
> > >>>>>>> We still believe that bare-metal database is needed
> > >>>>>>> because there is not an automated way how bare-metal nodes
> > >>>>>>> report
> > >>>>>>> their capabilities
> > >>>>>>> to their bare-metal nova-compute node.
> > >>>>>>>
> > >>>>>>> Thanks,
> > >>>>>>> David
> > >>>>>>>
> > >>>>>>>>
> > >>>>>>>> I am interested in finding a solution that enables bare-metal
> > >>>>>>>> and
> > >>>>>>>> virtualized requests to be serviced through the same
> > >>>>>>>> scheduler
> > >>>>>>>> where
> > >>>>>>>> the compute_nodes table has a full view of schedulable
> > >>>>>>>> resources.
> > >>>>>>>> This
> > >>>>>>>> would seem to simplify the end-to-end flow while opening up
> > >>>>>>>> some
> > >>>>>>>> additional use cases (e.g. dynamic allocation of a node from
> > >>>>>>>> bare-metal to hypervisor and back).
> > >>>>>>>>
> > >>>>>>>> One approach would be to have a proxy running a single
> > >>>>>>>> nova-compute
> > >>>>>>>> daemon fronting the bare-metal nodes . That nova-compute
> > >>>>>>>> daemon
> > >>>>>>>> would
> > >>>>>>>> report up many HostState objects (1 per bare-metal node) to
> > >>>>>>>> become
> > >>>>>>>> entries in the compute_nodes table and accessible through the
> > >>>>>>>> scheduler HostManager object.
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> The HostState object would set cpu_info, vcpus, member_mb and
> > >>>>>>>> local_gb
> > >>>>>>>> values to be used for scheduling with the hypervisor_host
> > >>>>>>>> field
> > >>>>>>>> holding the bare-metal machine address (e.g. for IPMI based
> > >>>>>>>> commands)
> > >>>>>>>> and hypervisor_type = NONE. The bare-metal Flavors are
> > >>>>>>>> created
> > >>>>>>>> with
> > >>>>>>>> an
> > >>>>>>>> extra_spec of hypervisor_type= NONE and the corresponding
> > >>>>>>>> compute_capabilities_filter would reduce the available hosts
> > >>>>>>>> to
> > >>>>>>>> those
> > >>>>>>>> bare_metal nodes. The scheduler would need to understand that
> > >>>>>>>> hypervisor_type = NONE means you need an exact fit (or
> > >>>>>>>> best-fit)
> > >>>>>>>> host
> > >>>>>>>> vs weighting them (perhaps through the multi-scheduler). The
> > >>>>>>>> scheduler
> > >>>>>>>> would cast out the message to the <topic>.<service-hostname>
> > >>>>>>>> (code
> > >>>>>>>> today uses the HostState hostname), with the compute driver
> > >>>>>>>> having
> > >>>>>>>> to
> > >>>>>>>> understand if it must be serviced elsewhere (but does not
> > >>>>>>>> break
> > >>>>>>>> any
> > >>>>>>>> existing implementations since it is 1 to 1).
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> Does this solution seem workable? Anything I missed?
> > >>>>>>>>
> > >>>>>>>> The bare metal driver already is proxying for the other nodes
> > >>>>>>>> so
> > >>>>>>>> it
> > >>>>>>>> sounds like we need a couple of things to make this happen:
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> a) modify driver.get_host_stats to be able to return a list
> > >>>>>>>> of
> > >>>>>>>> host
> > >>>>>>>> stats instead of just one. Report the whole list back to the
> > >>>>>>>> scheduler. We could modify the receiving end to accept a list
> > >>>>>>>> as
> > >>>>>>>> well
> > >>>>>>>> or just make multiple calls to
> > >>>>>>>> self.update_service_capabilities(capabilities)
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> b) make a few minor changes to the scheduler to make sure
> > >>>>>>>> filtering
> > >>>>>>>> still works. Note the changes here may be very helpful:
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> https://review.openstack.org/10327
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> c) we have to make sure that instances launched on those
> > >>>>>>>> nodes
> > >>>>>>>> take
> > >>>>>>>> up
> > >>>>>>>> the entire host state somehow. We could probably do this by
> > >>>>>>>> making
> > >>>>>>>> sure that the instance_type ram, mb, gb etc. matches what the
> > >>>>>>>> node
> > >>>>>>>> has, but we may want a new boolean field "used" if those
> > >>>>>>>> aren't
> > >>>>>>>> sufficient.
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> I This approach seems pretty good. We could potentially get
> > >>>>>>>> rid
> > >>>>>>>> of
> > >>>>>>>> the
> > >>>>>>>> shared bare_metal_node table. I guess the only other concern
> > >>>>>>>> is
> > >>>>>>>> how
> > >>>>>>>> you populate the capabilities that the bare metal nodes are
> > >>>>>>>> reporting.
> > >>>>>>>> I guess an api extension that rpcs to a baremetal node to add
> > >>>>>>>> the
> > >>>>>>>> node. Maybe someday this could be autogenerated by the bare
> > >>>>>>>> metal
> > >>>>>>>> host
> > >>>>>>>> looking in its arp table for dhcp requests! :)
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>> Vish
> > >>>>>>>>
> > >>>>>>>> _______________________________________________
> > >>>>>>>> OpenStack-dev mailing list
> > >>>>>>>> OpenStack-dev at lists.openstack.org
> > >>>>>>>>
http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> > >>>>>>>
> > >>>>>>> _______________________________________________
> > >>>>>>> OpenStack-dev mailing list
> > >>>>>>> OpenStack-dev at lists.openstack.org
> > >>>>>>>
http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> > >>>>>>
> > >>>>>>
> > >>>>>> _______________________________________________
> > >>>>>> OpenStack-dev mailing list
> > >>>>>> OpenStack-dev at lists.openstack.org
> > >>>>>>
http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> > >>>>>
> > >>>>> _______________________________________________
> > >>>>> OpenStack-dev mailing list
> > >>>>> OpenStack-dev at lists.openstack.org
> > >>>>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> > >>>>
> > >>>>
> > >>>> _______________________________________________
> > >>>> OpenStack-dev mailing list
> > >>>> OpenStack-dev at lists.openstack.org
> > >>>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
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Michael

-------------------------------------------------
Michael Fork
Cloud Architect, Emerging Solutions
IBM Systems & Technology Group
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