[Maas-devel] Support for ARM PXE booting, esp. in absence of control over DHCP

[Julian Edwards]

On Monday 20 August 2012 14:03:08 Gavin Panella wrote:
> On 20 August 2012 13:48, Robert Collins <robert.collins at canonical.com>
> wrote: ...
> 
> > Thats going to have substantial implications in development effort and
> > product complexity. Can you enlarge on the use case(s) that caused us
> > to invalidate 'assume we have dedicated DHCP controlled by MAAS' ?
> 
> It was clear in the IoM that we have to support this use-case, where
> users want to continue managing their networks their own way. We
> thrashed through some of this during that week, and it looks like we
> can do it without /too/ much bother.
> 
> The experience of using MAAS without its own DHCP control may differ
> from the experience of using it, but only in minor ways, and that's
> okay. The idea is to make it as good as possible and present the users
> with the choice. For example, publishing custom hostnames to DNS might
> be trickier, or fragile, and we ought to be able to present that as a
> reason to choose MAAS's DHCP.

There are two specific things that won't work unless we manage DHCP:
1. Figuring out what the leases are, and hence setting a CNAME in the DNS for 
the node's configured host name.
2. Ensuring a static MAC/IP mapping.

When we say "managed" DHCP, all it means is that we are using OMAPI to set 
these static host maps.  We don't dynamically configure the DHCP server like 
Cobbler does.  There's a tool to generate a suggested config if you want to 
use it though (this will be useful in packaging).

There will be instances where the user is unable to manage their own DHCP 
server (they could be using the one in a router for example).  We've got to 
the point where the loss of functionality is fairly minimal provided it at 
least handles PXE (next-server).