Re: discuss: NM server defaults

[Pavel Simerda <psimerda redhat com>]

> > Sounds like a useful default for specific class of usage. I, personally,
> > would prefer the server to react on carrier at least when using DHCP.
>
> So both you and danw didn't say *why*.

It's easy. When moving a server to a new location, I want it to accomodate the new network, that's why I'm 
using DHCP after all. But sometimes, I'm only moving it to another physical network while keeping the energy 
source. Then I would still like if it could accomodate the new network. Also, sometimes I'm using this 
feature to restart the connection process by unplugging the cable, or even restarting it for all devices by 
restarting a switch.

> My guess here is that in a
> server situation, we don't want to down the interface and request a new
> DHCP lease for a brief cable plug + unplug?

I don't really see a renew/rebind upon replugging as a problem. The opposite is true. When I'm unplugging 
cables, I'm doing it for a reason. When I'm restarting network 
equipment, I'm doing it for a reason. When I restart all network equipment and only keep servers with disks 
running, I expect the network to be in fresh state in a couple of minutes. This behavior spoils such a casual 
test and keeps my network as a whole in an inconsistent state, that doesn't match the state e.g. after a 
power outage. For me, reducing the risk of surprise is one of the keys to good system administration.

> If an admin accidentally unplugs the wrong one?

Then he plugs it back and the lease is renewed/rebound. I don't see the problem with that.

> > So this might actually be an area where we as developers don't know yet
> > whether it is preferable and by which groups of people.
>
> Right, that's the goal of this thread.  Review of above branch
> appreciated.

That's nice, but apparently there are many sysadmins with exactly opposite views than I have. And it happend 
to me in the past. We often had to speak out our preferences and their weight and then decide on something 
one of us was not entirely happy with. Just like it works with the development. Fortunately, in this case the 
consensus is to provide the full feature set and let the administrators decide. The question is, to what 
degree we can provide sensible defaults for them.

In my opinion, the default is to treat DHCP connections as fully dynamic on servers as well as on laptops. 
For me a DHCP-enabled laptop and a DHCP-enabled are no different at all. But apparently this is not the only 
possible opinion and it might just as well be a minority one.

Pavel