[systemd-devel] [PATCH 17/17] networkd: add dhcp server support

[Lennart Poettering]

On Tue, 27.05.14 22:14, Kirill Elagin (kirelagin at gmail.com) wrote:

> >
> > The container usecase alone is already the reason why I am so very sure
> > I want this stuff, and that it needs to be in networkd, and just work. I
> > want this fully automatic, so that we can create a hundred of veth
> > tunnels, and trivially easy (simply by setting DHCPServer=yes for their
> > .network file) make them automatically configured, passing the relevant
> > configuration bits on.
> 
> 
> I'm sorry to intervene, but there are other ways to configure containers
> and similar stuff. I mean, systemd is great because it pioneered so
> many cool things. Why can't we do something new? For example, prohibit
> IPv4 for containers and VMs and require them to use IPv6 with
> link-local

we don't really ever "prohibit" anything. People can do whatever they
want to do...

That said, I think IPv4 connectivity is kinda important if we ever want
to minimize the differences between container-based virtualization and
normal systems. I want containers to be as close to a real OS as
possible and that includes being able to communicate with the usual
internet.

I mean, we will have a strong focus on making things work with IPv6
nicely, and I have the suspicion we can make a number of things nicer
with Ipv6 than with IPv4 (since we could automatically assign an
externally routable IPv6 address for each container, which is not really
doable for IPv4).

> addresses which will eliminate the need for any kind of configuration.
> Pushing IPv6 forward is a good idea. But, well, if you find this
> unacceptable, what's wrong with IPv4LL?

Ipv4LL is inherently not routable. We want something here though that
can talk to the internet if it wants to.

> DHCP is complex (well, not _that_ complex, but still) and it's not
> always required. E.g. IPv6 networks can live without DHCP by using
> link-local addresses and, say, some basic NDP. It seems to me that
> IPv4LL should suffice for all the “container use-cases”.

DHCP is actually one of the simplest protocols I am aware of...

Lennart

-- 
Lennart Poettering, Red Hat