[Maas-devel] MAAS IP Allocation [was: Re: 1.6.0 beta 4 out]

[Mark Shuttleworth]

On 15/07/14 04:54, Andres Rodriguez wrote:
> Hi Julian,
> I do agree with you that it is very hard to change the IP on demand, and
> this should not be considered as part of the DHCP work.

Something like Landscape or another process might be able to change IP
addresses. So the guideline is:

 * something should be able to tell us about a machine they have
configured and want an IP address for that is not a "managed" machine
(ie. we're not doing PXE + OS install just DHCP + DNS)
 * that same thing (human or code) should be able to release the IP /
remove the unmanaged machine / change the IP / request a change in IP

>> There is a separate mechanism to permanently assign an IP to a node if the
>> admin wishes (the API for that is not coded yet but the underlying basics
>> are
>> in place).  Is this what folks want now?
>>
> I think that this is indeed something we want to be able to do. I think it
> is important for us to be able to assign an IP to a node's MAC address, so
> that when we configure things like bonding (in the future, or manually), we
> could choose what interface will be the default or the one answering ARP
> requests for the bond. We should be able to do this without even having the
> machine allocated to a user. (Only an admin should be able to do this).

Let's not worry about permissions for now. Let users get IP addresses
and release them if they need it. Later we can permission that
separately ("you need to be allocated an IP address") if we need it.

Also, don't be simplistic about "assigning to the MAC". Yes, that's true
for the base DHCP requirement. But scripted configs via cloud-init could
add aliases and other configurations on top. MAAS needs to know about those.

> I think that we can keep the current approach on how MAAS is assigning
> IP addresses, however, as briefly discussed via IRC with Julian, we
> can have a Setting option that would change this approach to basically
> do the following: 1. Pre-allocate IP address to nodes that have
> successfully "commissioned". 2. Change the IP allocation to a
> different MAC address or a different IP address, allowing DNS mapping
> to be updated without having the allocate / turn on the machine. 3. We
> could potentially allocate multiple IP's to a node, each one to a
> different MAC addresses. @James. We would really like to hear your input.

How about thinking about it differently? Instead of a system-wide
setting, how about saying:

 * you can bind an IP to a machine, in which case it is reserved for
that even if the machine is off
 * you can *unbind* an IP from a switched-off machine, which means it
will be released and a new one assigned when needed
 * if you haven't bound an IP to a machine then it is released when you
release the machine

Mark

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