Open Stack

On Wed, Jun 18, 2014 at 10:34 AM, Gary Kotton <gkotton at vmware.com> wrote:
>
>
> On 6/18/14, 4:19 PM, "Doug Hellmann" <doug.hellmann at dreamhost.com> wrote:
>
>>On Wed, Jun 18, 2014 at 4:47 AM, Gary Kotton <gkotton at vmware.com> wrote:
>>> Hi,
>>> I have encountered a problem with string substitution with the nova
>>> configuration file. The motivation was to move all of the glance
>>>settings to
>>> their own section (https://review.openstack.org/#/c/100567/). The
>>> glance_api_servers had default setting that uses the current
>>>glance_host and
>>> the glance port. This is a problem when we move to the Œglance¹ section.
>>> First and foremost I think that we need to decide on how we should
>>>denote
>>> the string substitutions for group variables and then we can dive into
>>> implementation details. Does anyone have any thoughts on this?
>>>
>>> My thinking is that when we use we should use a format of
>>>$<group>.<key>. An
>>> example is below.
>>>
>>> Original code:
>>>
>>>     cfg.ListOpt('glance_api_servers',
>>>                 default=['$glance_host:$glance_port'],
>>>                 help='A list of the glance api servers available to
>>>nova. '
>>>                      'Prefix with
>>>https://urldefense.proofpoint.com/v1/url?u=https:///&k=oIvRg1%2BdGAgOoM1B
>>>IlLLqw%3D%3D%0A&r=eH0pxTUZo8NPZyF6hgoMQu%2BfDtysg45MkPhCZFxPEq8%3D%0A&m=t
>>>PCYaurIa1F3hEMCd5LOOfvP785BZFa8M58fXpp0Lcw%3D%0A&s=2ac62a772fd5bd58fa7cf7
>>>0a973956ba97f933d649fb2f95be7b7d3e18d2b086 for ssl-based glance api
>>>servers.
>>> '
>>>                      '([hostname|ip]:port)'),
>>>
>>> Proposed change (in the glance section):
>>>     cfg.ListOpt('api_servers',
>>>                 default=[Œ$glance.host:$glance.port'],
>>>                 help='A list of the glance api servers available to
>>>nova. '
>>>                      'Prefix with
>>>https://urldefense.proofpoint.com/v1/url?u=https:///&k=oIvRg1%2BdGAgOoM1B
>>>IlLLqw%3D%3D%0A&r=eH0pxTUZo8NPZyF6hgoMQu%2BfDtysg45MkPhCZFxPEq8%3D%0A&m=t
>>>PCYaurIa1F3hEMCd5LOOfvP785BZFa8M58fXpp0Lcw%3D%0A&s=2ac62a772fd5bd58fa7cf7
>>>0a973956ba97f933d649fb2f95be7b7d3e18d2b086 for ssl-based glance api
>>>servers.
>>> '
>>>                      '([hostname|ip]:port)¹,
>>>                 deprecated_group='DEFAULT¹,
>>>
>>> deprecated_name='glance_api_servers'),
>>>
>>> This would require some preprocessing on the oslo.cfg side to be able to
>>> understand the $glance is the specific group and then host is the
>>>requested
>>> value int he group.
>>>
>>> Thanks
>>> Gary
>>
>>Do we need to set the variable off somehow to allow substitutions that
>>need the literal '.' after a variable? How often is that likely to
>>come up?
>
>
> To be honest I think that this is a real edge case. I had a chat with
> markmc on IRC and he suggested a different approach, which I liked,
> regarding the specific patch. That is, to set the default to None and when
> the data is accessed to check if it is is None. If so then provide the
> default values.

That sounds like a good solution, too, although we should be careful
about how we document the default value for that option.

Doug

>
> We may still nonetheless need something like this in the future.
>
>>
>>Doug
>>
>>>
>>>
>>> _______________________________________________
>>> 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