Open Stack

> On 2/25/2019 11:53 PM, yonglihe wrote:
>> The approved spec show-server-group had 2 options for response.
>>
>> 1. First one(current spec):
>>
>>           "server": {
>>              "server_groups": [ # not cached
>>                     "0b5d2c72-12cc-4ba6-a8d7-3ff5cc1d8cb8"
>>              ]
>>          }
>>     }
>>
>> related discuss:
>> https://review.openstack.org/#/c/612255/11/specs/stein/approved/show-server-group.rst@67
>>
>> digest:  This  decouple the current  implementation of server groups
>> then get a  generic API.
>
> Jay pushed for this on the spec review because it future-proofs the
> API in case a server can ever be in more than one group (currently it
> cannot). When I was reviewing the code this was the first thing that
> confused me (before I knew about the discussion on the spec) because I
> knew that a server can only be in at most one server group, and I
> think showing a list is misleading to the user. Similarly, before 2.64
> the os-server-groups API had a "policies" parameter which could only
> ever have exactly one entry in it, and in 2.64 that was changed to
> just be "policy" to reflect the actual usage. I don't think we're
> going to have support for servers in multiple groups anytime soon, so
> I personally don't think we need to future-proof the servers API
> response with a potentially misleading type (array) when we know the
> server can only ever be in one group. If we were to add multi-group
> support in the future, we could revisit this at the same time but I'm
> not holding my breath given previous attempts.

Personally, I agree with Jay and think that going for the list is
better. We know people have asked for multiple-group membership
before, and we have existing warts in our APIs where we've had to
convert from a singleton to a list, which are still ugly today.

>> 2 Second one:
>>
>>          "server": {
>>              "server_group": {
>>                  "name": "groupA",
>>                  "id": "0b5d2c72-12cc-4ba6-a8d7-3ff5cc1d8cb8"
>>              }
>>
>> related discuss:
>> https://review.openstack.org/#/c/612255/4/specs/stein/approved/list-server-group.rst@62
>
> This is the format I think we should use since it shows the actual
> cardinality of server to group we support today.

I totally get your reasoning for this, I just think that using a list
for a thing that can only be one-long currently is a fairly common
thing, and is worth the potential for minor confusion over the work
required to maybe someday expand it to N.

I don't feel overly strong about it and wouldn't spend much energy
trying to convince people. If you (or others) feel strongly, then that's
fine.

--Dan