[Openstack-operators] [openstack-dev] [nova][glance] Who needs multiple api_servers?

Eric Fried openstack at fried.cc
Fri Apr 28 14:05:06 UTC 2017


Blair, Mike-

	There will be an endpoint_override that will bypass the service
catalog.  It still only takes one URL, though.

			Thanks,
			Eric (efried)

On 04/27/2017 11:50 PM, Blair Bethwaite wrote:
> We at Nectar are in the same boat as Mike. Our use-case is a little
> bit more about geo-distributed operations though - our Cells are in
> different States around the country, so the local glance-apis are
> particularly important for caching popular images close to the
> nova-computes. We consider these glance-apis as part of the underlying
> cloud infra rather than user-facing, so I think we'd prefer not to see
> them in the service-catalog returned to users either... is there going
> to be a (standard) way to hide them?
> 
> On 28 April 2017 at 09:15, Mike Dorman <mdorman at godaddy.com> wrote:
>> We make extensive use of the [glance]/api_servers list.  We configure that on hypervisors to direct them to Glance servers which are more “local” network-wise (in order to reduce network traffic across security zones/firewalls/etc.)  This way nova-compute can fail over in case one of the Glance servers in the list is down, without putting them behind a load balancer.  We also don’t run https for these “internal” Glance calls, to save the overhead when transferring images.
>>
>> End-user calls to Glance DO go through a real load balancer and then are distributed out to the Glance servers on the backend.  From the end-user’s perspective, I totally agree there should be one, and only one URL.
>>
>> However, we would be disappointed to see the change you’re suggesting implemented.  We would lose the redundancy we get now by providing a list.  Or we would have to shunt all the calls through the user-facing endpoint, which would generate a lot of extra traffic (in places where we don’t want it) for image transfers.
>>
>> Thanks,
>> Mike
>>
>>
>>
>> On 4/27/17, 4:02 PM, "Matt Riedemann" <mriedemos at gmail.com> wrote:
>>
>>     On 4/27/2017 4:52 PM, Eric Fried wrote:
>>     > Y'all-
>>     >
>>     >   TL;DR: Does glance ever really need/use multiple endpoint URLs?
>>     >
>>     >   I'm working on bp use-service-catalog-for-endpoints[1], which intends
>>     > to deprecate disparate conf options in various groups, and centralize
>>     > acquisition of service endpoint URLs.  The idea is to introduce
>>     > nova.utils.get_service_url(group) -- note singular 'url'.
>>     >
>>     >   One affected conf option is [glance]api_servers[2], which currently
>>     > accepts a *list* of endpoint URLs.  The new API will only ever return *one*.
>>     >
>>     >   Thus, as planned, this blueprint will have the side effect of
>>     > deprecating support for multiple glance endpoint URLs in Pike, and
>>     > removing said support in Queens.
>>     >
>>     >   Some have asserted that there should only ever be one endpoint URL for
>>     > a given service_type/interface combo[3].  I'm fine with that - it
>>     > simplifies things quite a bit for the bp impl - but wanted to make sure
>>     > there were no loudly-dissenting opinions before we get too far down this
>>     > path.
>>     >
>>     > [1]
>>     > https://blueprints.launchpad.net/nova/+spec/use-service-catalog-for-endpoints
>>     > [2]
>>     > https://github.com/openstack/nova/blob/7e7bdb198ed6412273e22dea72e37a6371fce8bd/nova/conf/glance.py#L27-L37
>>     > [3]
>>     > http://eavesdrop.openstack.org/irclogs/%23openstack-keystone/%23openstack-keystone.2017-04-27.log.html#t2017-04-27T20:38:29
>>     >
>>     > Thanks,
>>     > Eric Fried (efried)
>>     > .
>>     >
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>>
>>     --
>>
>>     Thanks,
>>
>>     Matt
>>
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