Compute API in nova - show/list servers with details says security_groups is required in response but it's optional

[Matt Riedemann]

- [x] This doc is inaccurate in this way:

This came up in review:

https://review.opendev.org/#/c/685927/2//COMMIT_MSG@9

https://docs.openstack.org/api-ref/compute/#show-server-details

and

https://docs.openstack.org/api-ref/compute/#list-servers-detailed

response parameter tables both say that "security_groups" is a required field in the response but that's not true if the server does not have any attached ports which is possible. This is the server view builder code:

https://github.com/openstack/nova/blob/867401e575d2b27b9bc63ceda41cd85233545cd5/nova/api/openstack/compute/views/servers.py#L627

Note the key is not in the GET response if the server is not attached to any ports that have security groups.

I recreated in devstack by creating a server with no network:

$ openstack --os-compute-api-version 2.37 server create --flavor m1.tiny --image cirros-0.4.0-x86_64-disk --nic none --wait vm-no-net

And the security_groups key is not in the GET /servers/detail response:

$ curl -H "X-Auth-Token: $token" http://10.128.0.6/compute/v2.1/servers/detail | python -m json.tool | grep security_groups
  % Total % Received % Xferd Average Speed Time Time Time Current
                                 Dload Upload Total Spent Left Speed
100 1388 100 1388 0 0 8213 0 --:--:-- --:--:-- --:--:-- 8213

-----------------------------------
Release: on 2019-09-19 17:55:19
SHA: 9ca14e081860b1abcc0d676f253a472028690e29
Source: https://opendev.org/openstack/nova/src/api-ref/source/index.rst
URL: https://docs.openstack.org/api-ref/compute/

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/686517

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/686517
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=a7c3108bf78d2f48b48876a491ecbc69a7ce984f
Submitter: Zuul
Branch: master

commit a7c3108bf78d2f48b48876a491ecbc69a7ce984f
Author: Takashi NATSUME <email address hidden>
Date: Fri Oct 4 11:37:55 2019 +0900

    api-ref: Fix security groups parameters

    The security groups parameters are optional
    in the response of the following APIs.

    - GET /servers/detail
    - GET /servers/{server_id}
    - PUT /servers/{server_id}
    - POST /servers/{server_id}/action (rebuild)

    So fix them.

    Change-Id: Icc2315fd8b8c085de9d560de6ddf4c05aaaf6acb
    Closes-Bug: #1846656