Hi,

I would like to discuss how to handle systemd's new feature of
predictable network interface names. This is a rather hot topic in the
team I'm currently working in, and I'd like to solicit your opinions
about that.

On systems with more than one interface, the canonical way to handle
this issue in the past was "assume that eth0 is connected to network
foo, eth1 is connected to network bar, and eth2 is connected to
network baz" and to accept that things fail horribly if the order in
which network interfaces are detected changes.

While upstream's focus is as usual on desktop machines where Ethernet,
USB and WWAN interfaces come and go multiple times a day (see
upstream's reasoning in
https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/),
this seldomly happens in our happy server environment, which reduces
the breakage potential to disruptive kernel updates or vendor firmware
changes peddling with the order in which network interfaces are
enumerated.

This happens rather seldomly in my experience.

I would, however, like to stay with the new scheme since I see its
charms.

But, how would I handle this in a puppetized environment?

Currently, the code that is already, for example for a firewall
assumes that eth0 is the external interface, eth1 the internal one and
eth2 the perimeter networks.

In the new setup, all those interfaces can have different names
depending on different hardware being used. That means that the same
puppet code cannot be used on one firewall instance running on Dell
hardware and a second one running on HP hardware because BIOS indices
and/or PCI paths will vary. If I used the MAC scheme, things are even
worse since interface names will be different even on different pieces
of otherwise identical hardware.

Many of my team members thinkt hat one should simply turn of
predictable network interface names altgether and so that our old code
continues to work. I think that this would be a bad idea, but don't
have any logical arguments other than my gut feeling.

Generating udev rules to fix the network names (and assign names like
ext1, int1, per1) already in postinst of the OS does not work since we
don't know how the machine is going to be wired and even used.

Any ideas? How do _you_ do this?

Greetings
Marc

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