[rfe][ml2] Add a new API that supports cloning a specified security group

[Liu Xie]

Hi everyone：
  We want to define a new api that supports cloning a specified security_group.
  Consider the following case:
  If the user wants to create a new security_group with the same rules as a created security_group, he should do some duplicate actions to create rules.

  It looks expensive, so that we want to define a new API that supports create a new security_group and automatically copy the rules from the specified security_group.

API likes:
PUT /v2.0/security-groups/{security_group_id}/clone

{
    "security_group": {
        "name": "newsecgroup",
        "description": "cloning security group from test",
        "stateful": true
    }
}

Does anyone have other ideas?

[Brian Haley (brian-haley)]

There is a new change to define a default SG template, https://bugs.launchpad.net/neutron/+bug/1983053 - it lets an admin define the default.

Who is the intended audience of a 'clone' API?

[LIU Yulong (dragon889)]

This request is reasonable, but this kind of orchestration operation can be done at a higher API gateway layer. Neutron API should keep concise and fundamental.

[Liu Xie (liushy)]

@LIU Yulong
Yeah, this api-ref needs to be disscussed and we all need to agree on it.
Do you have any suggestions?

[Rodolfo Alonso (rodolfo-alonso-hernandez)]

This RFE was NOT approved during the drivers meeting celebrated today [1]. The main reasons:
* As commented in c#2, this can be achieved with the current API and some scripting.
* The Neutron API should be keep "concise and fundamental"; let's keep the API "atomic".
* The RFE currently being implemented [2] that defines a set of default rules, could be used instead.

In any case, thanks for your time and this proposal.

[1]https://meetings.opendev.org/meetings/neutron_drivers/2023/neutron_drivers.2023-06-30-14.00.log.html
[2]https://bugs.launchpad.net/neutron/+bug/1983053