Open Stack

Hi,

Good questions: why not just keeping multiple endpoints, and leaving
orchestration effort in the client side?

>From feedback of some large data center operators, they want the cloud
exposed to tenant as a single region with multiple AZs, while each AZ
may be distributed in different/same locations, very similar with AZ
concept of AWS. And the OpenStack API is indispensable for the cloud
for eco-system friendly.

The cascading is mainly doing one thing: map each standalone child
Openstack to AZs in the parent Openstack, hide separated child
endpoints, thus converge them into a single standard OS-API endpoint.

One of the obvious benefit doing so is the networking: we can create a
single Router/LB, with subnet/port member from different child, just
like in a single OpenStack instance. Without the parent OpenStack
working as the aggregation layer, it is not so easy to do so. Explicit
VPN endpoint may be required in each child.

Best Regards
Wu Hongning

On Tue, Oct 7, 2014 at 11:30 PM, Monty Taylor <mordred at inaugust.com> wrote:
> On 10/07/2014 06:41 AM, Duncan Thomas wrote:
>> My data consistency concerts would be around:
>>
>> 1) Defining global state. You can of course hand wave away a lot of
>> your issues by saying they are all local to the sub-unit, but then
>> what benefit are you providing .v. just providing a list of endpoints
>> and teaching the clients to talk to multiple endpoints, which is far
>> easier to make reliable than a new service generally is. State that
>> 'ought' to be global: quota, usage, floating ips, cinder backups, and
>> probably a bunch more
>
> BTW - since infra regularly talks to multiple clouds, I've been working
> on splitting supporting code for that into a couple of libraries. Next
> pass is to go add support for it to the clients, and it's not really a
> lot of work ... so let's assume that the vs. here is going to be
> accomplished soonish for the purposes of assessing the above question.
>
> Second BTW - you're certainly right about the first two in the global
> list - we keep track of quota and usage ourselves inside of nodepool.
> Actually - since nodepool already does a bunch of these things - maybe
> we should just slap a REST api on it...
>
>> 2) Data locality expectations. You have to be careful about what
>> expectations .v. realty you're providing here. If the user experience
>> is substantially different using your proxy .v. direct API, then I
>> don't think you are providing a useful service - again, just teach the
>> clients to be multi-cloud aware. This includes what can be connected
>> to what (cinder volumes, snaps, backups, networks, etc), replication
>> behaviours and speeds (swift) and probably a bunch more that I haven't
>> thought of yet.
>>
>>
>>
>> On 7 October 2014 14:24, joehuang <joehuang at huawei.com> wrote:
>>> Hello, Joshua,
>>>
>>> Thank you for your concerns on OpenStack cascading. I am afraid that I am not proper person to give comment on cells, but I would like to speak a little about cascading for you mentioned "with its own set of consistency warts I'm sure" .
>>>
>>> 1. For small scale or a cloud within one data centers, one OpenStack instance (including cells) without cascading feature can work just like it work today. OpenStack cascading just introduces Nova-proxy, Cinder-proxy, L2/L3 proxy... like other vendor specific agent/driver( for example, vcenter driver, hyper-v driver, linux-agent.. ovs-agent ), and does not change the current architecture for Nova/Cinder/Neutron..., and does not affect the aleady developed features and deployment capability. The cloud operators can skip the existence of OpenStack cascading if they don't want to use it, just like they don't want to use some kinds of hypervisor / sdn controller ....
>>>
>>> 2. Could you provide concrete inconsistency issues you are worried about in OpenStack cascading? Although we did not implement inconsistency check in the PoC source code completely, but because logical VM/Volume/Port/Network... objects are stored in the cascading OpenStack, and the physical objects are stored in the cascaded OpenStack, uuid mapping between logical object and physical object had been built,  it's possible and easy to solve the inconsistency issues. Even for flavor, host aggregate, we have method to solve the inconsistency issue.
>>>
>>> Best Regards
>>>
>>> Chaoyi Huang ( joehuang )
>>> ________________________________________
>>> From: Joshua Harlow [harlowja at outlook.com]
>>> Sent: 07 October 2014 12:21
>>> To: OpenStack Development Mailing List (not for usage questions)
>>> Subject: Re: [openstack-dev] [all] [tc] Multi-clouds integration by     OpenStack cascading
>>>
>>> On Oct 3, 2014, at 2:44 PM, Monty Taylor <mordred at inaugust.com> wrote:
>>>
>>>> On 09/30/2014 12:07 PM, Tim Bell wrote:
>>>>>> -----Original Message-----
>>>>>> From: John Garbutt [mailto:john at johngarbutt.com]
>>>>>> Sent: 30 September 2014 15:35
>>>>>> To: OpenStack Development Mailing List (not for usage questions)
>>>>>> Subject: Re: [openstack-dev] [all] [tc] Multi-clouds integration by OpenStack
>>>>>> cascading
>>>>>>
>>>>>> On 30 September 2014 14:04, joehuang <joehuang at huawei.com> wrote:
>>>>>>> Hello, Dear TC and all,
>>>>>>>
>>>>>>> Large cloud operators prefer to deploy multiple OpenStack instances(as
>>>>>> different zones), rather than a single monolithic OpenStack instance because of
>>>>>> these reasons:
>>>>>>>
>>>>>>> 1) Multiple data centers distributed geographically;
>>>>>>> 2) Multi-vendor business policy;
>>>>>>> 3) Server nodes scale up modularized from 00's up to million;
>>>>>>> 4) Fault and maintenance isolation between zones (only REST
>>>>>>> interface);
>>>>>>>
>>>>>>> At the same time, they also want to integrate these OpenStack instances into
>>>>>> one cloud. Instead of proprietary orchestration layer, they want to use standard
>>>>>> OpenStack framework for Northbound API compatibility with HEAT/Horizon or
>>>>>> other 3rd ecosystem apps.
>>>>>>>
>>>>>>> We call this pattern as "OpenStack Cascading", with proposal described by
>>>>>> [1][2]. PoC live demo video can be found[3][4].
>>>>>>>
>>>>>>> Nova, Cinder, Neutron, Ceilometer and Glance (optional) are involved in the
>>>>>> OpenStack cascading.
>>>>>>>
>>>>>>> Kindly ask for cross program design summit session to discuss OpenStack
>>>>>> cascading and the contribution to Kilo.
>>>>>>>
>>>>>>> Kindly invite those who are interested in the OpenStack cascading to work
>>>>>> together and contribute it to OpenStack.
>>>>>>>
>>>>>>> (I applied for “other projects” track [5], but it would be better to
>>>>>>> have a discussion as a formal cross program session, because many core
>>>>>>> programs are involved )
>>>>>>>
>>>>>>>
>>>>>>> [1] wiki: https://wiki.openstack.org/wiki/OpenStack_cascading_solution
>>>>>>> [2] PoC source code: https://github.com/stackforge/tricircle
>>>>>>> [3] Live demo video at YouTube:
>>>>>>> https://www.youtube.com/watch?v=OSU6PYRz5qY
>>>>>>> [4] Live demo video at Youku (low quality, for those who can't access
>>>>>>> YouTube)：http://v.youku.com/v_show/id_XNzkzNDQ3MDg4.html
>>>>>>> [5]
>>>>>>> http://www.mail-archive.com/openstack-dev@lists.openstack.org/msg36395
>>>>>>> .html
>>>>>>
>>>>>> There are etherpads for suggesting cross project sessions here:
>>>>>> https://wiki.openstack.org/wiki/Summit/Planning
>>>>>> https://etherpad.openstack.org/p/kilo-crossproject-summit-topics
>>>>>>
>>>>>> I am interested at comparing this to Nova's cells concept:
>>>>>> http://docs.openstack.org/trunk/config-reference/content/section_compute-
>>>>>> cells.html
>>>>>>
>>>>>> Cells basically scales out a single datacenter region by aggregating multiple child
>>>>>> Nova installations with an API cell.
>>>>>>
>>>>>> Each child cell can be tested in isolation, via its own API, before joining it up to
>>>>>> an API cell, that adds it into the region. Each cell logically has its own database
>>>>>> and message queue, which helps get more independent failure domains. You can
>>>>>> use cell level scheduling to restrict people or types of instances to particular
>>>>>> subsets of the cloud, if required.
>>>>>>
>>>>>> It doesn't attempt to aggregate between regions, they are kept independent.
>>>>>> Except, the usual assumption that you have a common identity between all
>>>>>> regions.
>>>>>>
>>>>>> It also keeps a single Cinder, Glance, Neutron deployment per region.
>>>>>>
>>>>>> It would be great to get some help hardening, testing, and building out more of
>>>>>> the cells vision. I suspect we may form a new Nova subteam to trying and drive
>>>>>> this work forward in kilo, if we can build up enough people wanting to work on
>>>>>> improving cells.
>>>>>>
>>>>>
>>>>> At CERN, we've deployed cells at scale but are finding a number of architectural issues that need resolution in the short term to attain feature parity. A vision of "we all run cells but some of us have only one" is not there yet. Typical examples are flavors, security groups and server groups, all of which are not yet implemented to the necessary levels for cell parent/child.
>>>>>
>>>>> We would be very keen on agreeing the strategy in Paris so that we can ensure the gap is closed, test it in the gate and that future features cannot 'wishlist' cell support.
>>>>
>>>> I agree with this. I know that there are folks who don't like cells -
>>>> but I think that ship has sailed. It's there - which means we need to
>>>> make it first class.
>>>
>>> Just out of curiosity, would you prioritize cells over split out unified quotas, or a split out scheduler, or split out virt drivers, or a split out ..., or upgrades that work reliably or db quota consistency ([2]) or the other X things that need to be done to keep the 'openstack' ship afloat (neutron integration/migrations... the list can go on and on)?
>>>
>>> To me that's the part that has always bugged me about cells, it seems like we have bigger 'fish to fry' to get the whole system working in a good manner instead of adding yet another fish in to the already overwhelmed fishery (this is an analogy, not reality, ha). It somehow didn't/doesn't feel right that we have so many other pieces of the puzzle that need work just to operate at a small scale that we should add another component in that makes the system as a whole that much harder to get right (with lovely commits such as [1]). Aka, focus on a building a solid 'small house' first before trying to build a mansion if you will, because if you can't build a stable small house you'll likely build a mansion that will crumble in on itself...
>>>
>>> It also doesn't help that cells are a nova-specific concept that it doesn't seem like other projects have adopted (for better or worse) although this cascading design can be an alternative that could span across projects (with its own set of consistency warts I'm sure).
>>>
>>> [1] https://github.com/openstack/nova/blob/master/nova/compute/api.py#L1553 (what u wanted quota consistency?)
>>> [2] https://review.openstack.org/#/c/125181/
>>>
>>>>
>>>>> Resources can be made available if we can agree the direction but current reviews are not progressing (such as https://bugs.launchpad.net/nova/+bug/1211011)
>>>>>
>>>>> Tim
>>>>>
>>>>>> Thanks,
>>>>>> John
>>>>>>
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>>>>
>>>>
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>>
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