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<div class="moz-cite-prefix">On 06.02.2016 00:03, Salvatore Orlando
wrote:<br>
</div>
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cite="mid:CAP0B2WOA56=uw3SEXp3EW-t11nBfnxbx8jhYodR2g0Q=Y81xQA@mail.gmail.com"
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<div class="gmail_quote">On 5 February 2016 at 17:58, Neil
Jerram <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:Neil.Jerram@metaswitch.com" target="_blank">Neil.Jerram@metaswitch.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex"><span
class="">On 05/02/16 16:31, Pavel Bondar wrote:<br>
> On 05.02.2016 12:28, Salvatore Orlando wrote:<br>
>><br>
>><br>
>> On 5 February 2016 at 04:12, Armando M. <<a
moz-do-not-send="true" href="mailto:armamig@gmail.com"><a class="moz-txt-link-abbreviated" href="mailto:armamig@gmail.com">armamig@gmail.com</a></a><br>
</span><span class="">>> <mailto:<a
moz-do-not-send="true" href="mailto:armamig@gmail.com"><a class="moz-txt-link-abbreviated" href="mailto:armamig@gmail.com">armamig@gmail.com</a></a>>>
wrote:<br>
>><br>
>><br>
>><br>
>> On 4 February 2016 at 08:22, John Belamaric<br>
</span>>> <<mailto:<a
moz-do-not-send="true"
href="mailto:jbelamaric@infoblox.com"><a class="moz-txt-link-abbreviated" href="mailto:jbelamaric@infoblox.com">jbelamaric@infoblox.com</a></a>><a
moz-do-not-send="true"
href="mailto:jbelamaric@infoblox.com"><a class="moz-txt-link-abbreviated" href="mailto:jbelamaric@infoblox.com">jbelamaric@infoblox.com</a></a>>
wrote:<br>
>><br>
>><br>
>> > On Feb 4, 2016, at 11:09 AM, Carl
Baldwin <<a moz-do-not-send="true"
href="mailto:carl@ecbaldwin.net">carl@ecbaldwin.net</a>
<mailto:<a moz-do-not-send="true"
href="mailto:carl@ecbaldwin.net">carl@ecbaldwin.net</a>>>
wrote:<br>
<span class="">>> ><br>
>> > On Thu, Feb 4, 2016 at 7:23 AM,
Pavel Bondar <<a moz-do-not-send="true"
href="mailto:pbondar@infoblox.com">pbondar@infoblox.com</a>
<mailto:<a moz-do-not-send="true"
href="mailto:pbondar@infoblox.com">pbondar@infoblox.com</a>>>
wrote:<br>
>> >> I am trying to bring more
attention to [1] to make final decision on<br>
>> >> approach to use.<br>
>> >> There are a few point that are
not 100% clear for me at this point.<br>
>> >><br>
>> >> 1) Do we plan to switch all
current clouds to pluggable ipam<br>
>> >> implementation in Mitaka?<br>
<br>
</span>I possibly shouldn't comment at all, as I don't
know the history, and<br>
wasn't around when the fundamental design decisions here
were being made.<br>
<br>
However, it seems a shame to me that this was done in a
way that needs a<br>
DB migration at all. (And I would have thought it
possible for the<br>
default pluggable IPAM driver to use the same DB state as
the<br>
non-pluggable IPAM backend, given that it is delivering
the same<br>
semantics.) Without that, I believe it should be a
no-brainer to switch<br>
unconditionally to the pluggable IPAM backend.<br>
</blockquote>
<div><br>
</div>
<div>This was indeed the first implementation attempt that
we made, but it failed spectacularly as we wrestled with
different foreign key relationships in the original and
new model.</div>
<div>Pavel has all the details, but after careful
considerations we decided to adopt a specular model with
different db tables.</div>
</div>
</div>
</div>
</blockquote>
Yeah, we had this chicken and egg problem on subnet creation.<br>
<br>
On the one hand, ipam driver create_subnet has to be called *before*
creating neutron subnet.<br>
Because for AnySubnetRequest ipam driver is responsible for
selecting cidr for subnet.<br>
<br>
On the other hand, during ipam driver create_subnet call
availability ranges has to be created,<br>
but they are linked with neutron subnet using foreign key (with
allocation pools in the middle).<br>
So availability ranges could not be created before neutron subnet
due to FK constraint in old tables.<br>
<br>
To solve this chicken and egg problem it was decided to use tables
for reference driver that have no FK to neutron subnet.<br>
And it allowed to call ipam driver create_subnet (and create
availability ranges) before creating neutron subnet.<br>
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<br>
Sorry if that's unhelpful...<br>
<span class="HOEnZb"><font color="#888888"><br>
Neil<br>
</font></span>
<div class="HOEnZb">
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