maas-devel team mailing list archive

[Robbie Williamson <robbie.williamson@xxxxxxxxxxxxx>]

On 07/19/2012 04:59 PM, Robert Collins wrote:
> On Fri, Jul 20, 2012 at 9:48 AM, Clint Byrum <clint@xxxxxxxxxx> wrote:
>> Excerpts from Gavin Panella's message of 2012-07-19 05:26:38 -0700:
>>> On 19 July 2012 10:52, Julian Edwards <julian.edwards@xxxxxxxxxxxxx> wrote:
>>> ...
>>>>  * Write the entire zone file when adding/updating node groups by generating
>>>> hostnames based on IP (like ec2 does).
>>>
>>> Something I hadn't thought about before: what is the benefit of this
>>> over just using IP addresses?
>>>
>>
>> Without this level of indirection, machines will be cemented in one
>> place on a network. While MaaS doesn't want a machine to be a special
>> snowflake, it doesn't want to require re-deploying everything just to
>> change the routing on your network.
> 
> !cite - seriously, in a cloud focused approach, I don't see how you
> get from A to B. We're anticipating RFC1918 addresses, so public
> routable changes should be of little or no consequence. And changes to
> RFC1918 space stuff is extremely rare. Add to that that graceful moves
> usually involve rotating services to avoid downtime, and my conclusion
> is that network renumbering isn't an interesting use case for us.
> (Also see again with EC2, the largest and most mature cloud around -
> they don't support network renumbering either).
> 
>> DNS is still important even when you are the ones controlling the
>> addresses. In fact, it should be a lot simpler to get right given that
>> position.
> 
> Simpler than if we didn't, yes. Simpler than not doing it at all: no.
> 
> I think we need to go back to the archetypical users and their needs -
> the seed cloud, the production + staging clouds, the hyperscale
> clouds, and investigate what jobs they are doing that DNS offers them
> value on. I suspect its approximately nothing, particularly as we
> scale and memorability diminishes in importance.
> 

+1

My $0.02: I think dynamically generated DHCP hostnames is fine. DNS is
only useful when machines are doing specific tasks, such as in a
traditional datacenter.  In this case, I'm not sure I'd even recommend
using the MAAS, unless you simply need an easy way to install and do
hardware inventory on them...a Landscape upsell seems better in terms of
what you get.  If it's truly a service of machines, then you don't care
about individual machines, and thus names are irrelevant.  You care
about their constraints, e.g. arch, cpus, disk, maybe even physical
location,  but you intend to deploy and interact with the service
overlayed...not the machine. If you happen to need to log into a
specific machine, Juju can tell you based on the status of the service.

-Robbie


-- 
Robbie Williamson <robbie.williamson@xxxxxxxxxxxxx>
Director of Engineering, Ubuntu Server
Canonical

"You can't be lucky all the time, but you can be smart everyday"
 -Mos Def