[openstack-dev] [nova][neutron] How would nova microversion get-me-a-network in the API?

Jay Pipes jaypipes at gmail.com
Mon Feb 22 12:01:26 UTC 2016

On 02/22/2016 06:56 AM, Sean Dague wrote:
> On 02/19/2016 12:49 PM, John Garbutt wrote:
> <snip>
>> Consider a user that uses these four clouds:
>> * nova-network flat DHCP
>> * nova-network VLAN manager
>> * neutron with a single provider network setup
>> * neutron where user needs to create their own network
>> For the first three, the user specifies no network, and they just get
>> a single NIC with some semi-sensible IP address, likely with a gateway
>> to the internet.
>> For the last one, the user ends up with a network with zero NICs. If
>> they then go and configure a network in neutron (and they can now use
>> the new easy one shot give-me-a-network CLI), they start to get VMs
>> just like they would have with nova-network VLAN manager.
>> We all agree the status quo is broken. For me, this is a bug in the
>> API where we need to fix the consistency. Because its a change in the
>> behaviour, it needs to be gated by a micro version.
>> Now, if we step back and created this again, I would agree that
>> --nic=auto is a good idea, so its explicit. However, all our users are
>> used to automatic being the default, all be it a very patchy default.
>> So I think the best evolution here is to fix the inconsistency by
>> making a VM with no network being the explicit option (--no-nic or
>> something?), and failing the build if we are unable to get a nic using
>> an "automatic guess" route. So now the default is more consistent, and
>> those that what a VM with no NIC have a way to get their special case
>> sorted.
>> I think this means I like "option 2" in the summary mail on the ops list.
> Thinking through this over the weekend.
>  From the API I think I agree with Laski now. An API shouldn't doesn't
> typically need default behavior, it's ok to make folks be explicit. So
> making nic a required parameter is fine.
> "nic": "auto"
> "nic": "none"
> "nic": "$name"
> nic is now jsonschema enforced, 400 if not provided.
> that being said... I think the behavior of CLI tools should default to
> nic auto being implied. The user experience there is different. You use
> cli tools for one off boots of things, so should be as easy as possible.
> I think this is one of the places where the UX needs of the API and the
> CLI are definitely different.

I'd be cool with this, too.


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