Open Stack

Great stuff! Thank you Ronan. I'd love to see this guide refactored
and submitted to our docs (also take a longer look how to make full
fledged support in kolla tree). Looking for volunteers:)

On 5 January 2017 at 07:59, Jeffrey Zhang <zhang.lei.fly at gmail.com> wrote:
> Thanks Ronan,
>
> Great approach.
>
> I am always expecting multi-region support in Kolla. I hope what you did can
> be merged into Kolla.
>
>
>
> On Thu, Jan 5, 2017 at 10:12 PM, Ronan-Alexandre Cherrueau
> <ronan-alexandre.cherrueau at inria.fr> wrote:
>>
>> Hello,
>>
>>
>> TL;DR: We make a multi-regions deployment with Kolla. It requires to
>> patch the code a little bit, and you can find the diff on our
>> GitHub[1]. This patch is just a first attempt to support multi-regions
>> in Kolla and it raises questions. Some modifications are not done in
>> an idiomatic way and we do not expect this to be merged in Kolla. The
>> reminder of this mail explains our patch and states our questions.
>>
>>
>> At Inria/Discovery[2], we evaluate OpenStack at scale for the
>> Performance Working Group. So far, we focus on one single OpenStack
>> region deployment with hundreds of computes and we always go with
>> Kolla for our deployment. Over the last few days, we tried to achieve
>> a multi-regions OpenStack deployment with Kolla. We want to share with
>> you our current deployment workflow, patches we had to apply on Kolla
>> to support multi-regions, and also ask you if we do things correctly.
>>
>> First of all, our multi-regions deployment follows the one described
>> by the OpenStack documentation[3]. Concretely, the deployment
>> considers /one/ Administrative Region (AR) that contains Keystone and
>> Horizon. This is a Kolla-based deployment, so Keystone is hidden
>> behind an HAProxy, and has MariaDB and memcached as backend. At the
>> same time, /n/ OpenStack Regions (OSR1, ..., OSRn) contain a full
>> OpenStack, except Keystone. We got something as follows at the end of
>> the deployment:
>>
>>
>> Admin Region (AR):
>> - control:
>>   * Horizon
>>   * HAProxy
>>   * Keyston
>>   * MariaDB
>>   * memcached
>>
>> OpenStack Region x (OSRx):
>> - control:
>>   * HAProxy
>>   * nova-api/conductor/scheduler
>>   * neutron-server/l3/dhcp/...
>>   * glance-api/registry
>>   * MariaDB
>>   * RabbitMQ
>>
>> - compute1:
>>   * nova-compute
>>   * neutron-agent
>>
>> - compute2: ...
>>
>>
>> We do the deployment by running Kolla n+1 times. The first run deploys
>> the Administrative Region (AR) and the other runs deploy OpenStack
>> Regions (OSR). For each run, we fix the value of `openstack_region_name'
>> variable to the name of the current region.
>>
>> In the context of multi-regions, Keystone (in the AR) should be
>> available to all OSRs. This means, there are as many Keystone
>> endpoints as regions. For instance, if we consider two OSRs, the
>> result of listing endpoints at the end of the AR deployment looks like
>> this:
>>
>>
>>  $ openstack endpoint list
>>
>>  | Region | Serv Name | Serv Type | Interface | URL
>> |
>>
>> |--------+-----------+-----------+-----------+------------------------------|
>>  | AR     | keystone  | identity  | public    |
>> http://10.24.63.248:5000/v3  |
>>  | AR     | keystone  | identity  | internal  |
>> http://10.24.63.248:5000/v3  |
>>  | AR     | keystone  | identity  | admin     |
>> http://10.24.63.248:35357/v3 |
>>  | OSR1   | keystone  | identity  | public    |
>> http://10.24.63.248:5000/v3  |
>>  | OSR1   | keystone  | identity  | internal  |
>> http://10.24.63.248:5000/v3  |
>>  | OSR1   | keystone  | identity  | admin     |
>> http://10.24.63.248:35357/v3 |
>>  | OSR2   | keystone  | identity  | public    |
>> http://10.24.63.248:5000/v3  |
>>  | OSR2   | keystone  | identity  | internal  |
>> http://10.24.63.248:5000/v3  |
>>  | OSR2   | keystone  | identity  | admin     |
>> http://10.24.63.248:35357/v3 |
>>
>>
>> This requires patching the `keystone/tasks/register.yml' play[4] to
>> re-execute the `Creating admin project, user, role, service, and
>> endpoint' task for all regions we consider. An example of such a patch
>> is given on our GitHub[5]. In this example, the `openstack_regions'
>> variable is a list that contains the name of all regions (see [6]). As
>> a drawback, the patch implies to know in advance all OSR. A better
>> implementation would execute the `Creating admin project, user, role,
>> service, and endpoint' task every time a new OSR is going to be
>> deployed. But this requires to move the task somewhere else in the
>> Kolla workflow and we have no idea where this should be.
>>
>> In the AR, we also have to change the Horizon configuration file to
>> handle multi-regions[7]. The modification could be done easily and
>> idiomatically by setting the `node_custome_config' variable to the
>> `multi-regions' directory[8] and benefits from Kolla merging config
>> system.
>>
>> Also, deploying OSRs requires patching the kolla-toolbox as it seems
>> not region-aware. In particular, patch the `kolla_keystone_service.py'
>> module[9] that is responsible for contacting Keystone and creating a
>> new endpoint when we register a new OpenStack service.
>>
>>
>>  73  for _endpoint in cloud.keystone_client.endpoints.list():
>>  74      if _endpoint.service_id == service.id and \
>>  75         _endpoint.interface == interface:
>>  76        endpoint = _endpoint
>>  77        if endpoint.url != url:
>>  78          changed = True
>>  79          cloud.keystone_client.endpoints.update(
>>  80            endpoint, url=url)
>>  81        break
>>  82  else:
>>  83    changed = True
>>  84    cloud.keystone_client.endpoints.create(
>>  85      service=service.id,
>>  86      url=url,
>>  87      interface=interface,
>>  88      region=endpoint_region)
>>
>>
>> At some point, this module /create/ or /update/ a service endpoint. It
>> first tests if the service is already registered, and update the URL
>> if so (l. 74 to 81), or create the new endpoint in other cases (l.
>> 82). Unfortunately, the test (l. 74 to 75) only looks at the service
>> (e.g., glance) and the interface (e.g., public). This makes the test
>> wrong because we deploy the same service many times, but into
>> different regions. We have to add an extra condition to not only test
>> the service but also its region.
>>
>>
>>  74  if _endpoint.service_id == service.id and \
>>  75     _endpoint.interface == interface and \
>>  76     _endpoint.region == endpoint_region:
>>
>>
>> Finally, when we deployed OSRs, we override the value of
>> `keystone_admin_url', `keystone_internal_url' and `keystone_public_url'
>> to target Keystone in AR. We also have to change the
>> `[keystone_authtoken]' section of nova/neutron/glance conf[10] so that
>> it uses these variables instead of the canonical form with the
>> `kolla_internal_fqdn' variable[11]. In this regards, is it due to some
>> legacy code that configuration files use the `kolla_internal_fqdn'
>> variable instead of `keystone_*_url'?
>>
>> That's almost all. As you can see, handle multi-regions implies a very
>> small number of modifications if you call Kolla multiple times.
>>
>> So, thanks for the great job Kolla team! And waiting for your
>> feedback.
>>
>>
>>
>> [1]
>> https://github.com/BeyondTheClouds/kolla/commit/7e5f7e6c7936b7cc3136dfc082935e2995a65554
>> [2] https://beyondtheclouds.github.io/
>> [3] http://docs.openstack.org/arch-design/multi-site-architecture.html
>> [4]
>> https://github.com/openstack/kolla/blob/11bfd9eb7518cc46ac441505a267f5cf974216ae/ansible/roles/keystone/tasks/register.yml
>> [5]
>> https://github.com/BeyondTheClouds/kolla/commit/7e5f7e6c7936b7cc3136dfc082935e2995a65554#diff-40be75c3a2237adfd1a05178f6f60006R1
>> [6]
>> https://github.com/BeyondTheClouds/kolla/commit/7e5f7e6c7936b7cc3136dfc082935e2995a65554#diff-607e6e5925d0031dafa79eb80d198640R215
>> [7]
>> https://github.com/BeyondTheClouds/kolla/commit/7e5f7e6c7936b7cc3136dfc082935e2995a65554#diff-6cbb63bb9c4843bcf8db4710e588475bR188
>> [8]
>> https://github.com/BeyondTheClouds/kolla/tree/7e5f7e6c7936b7cc3136dfc082935e2995a65554/multi-regions
>> [9]
>> https://github.com/BeyondTheClouds/kolla/commit/7e5f7e6c7936b7cc3136dfc082935e2995a65554#diff-ba10dd4575f65e03d50d586febdccbadR72
>> [10]
>> https://github.com/BeyondTheClouds/kolla/blob/7e5f7e6c7936b7cc3136dfc082935e2995a65554/multi-regions/global.conf
>> [11]
>> https://github.com/openstack/kolla/blob/11bfd9eb7518cc46ac441505a267f5cf974216ae/ansible/roles/nova/templates/nova.conf.j2#L155
>>
>>
>> --
>> Ronan-A. Cherrueau
>>
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>
>
>
>
> --
> Regards,
> Jeffrey Zhang
> Blog: http://xcodest.me
>
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