[Pkg-utopia-maintainers] Bug#854801: No network after netinst Stretch RC2

[Bernhard Schmidt]

Hi

On 13.02.2017 18:24, Paul Schlüter wrote:
> Am Montag, den 13.02.2017, 10:31 +0100 schrieb Bernhard Schmidt:
>> @Paul: Can you share the installer log (/var/log/installer/syslog) and
>> the content of your /etc/network/interfaces after installation? I'll try
>> to get that information myself tonight, I don't have RDNSS here in the
>> office network unfortunately.
> 
> Hi Bernhard,
> 
> please find attached
> 
> - installer-log.gz: /var/log/installer/syslog
> - interfaces: original (and current) /etc/network/interfaces
> 
> (I reverted my modification of "interfaces" after the installation of
> network-manager-gnome).

So, I've tried to reproduce the issue and failed. I'm in a qemu VM on a
network that provides IPv6 SLAAC with RDNSS and IPv4 DHCP. I have booted
using the RC2-netinst-amd64 image and installed the XFCE desktop task.

As expected I ended up with rdnssd installed (no network-manager), but
/etc/network/interfaces is properly populated and I got network
connectivity.

I think I have found the source of your problem. According to your logs
you are installing on a WiFi interface (wlp2s0). The first attempt to
write your /etc/network/interfaces shows correct stanzas for the interface

Feb  9 06:32:45 netcfg[6883]: DEBUG: Network config complete
Feb  9 06:32:45 netcfg[6883]: DEBUG: No interface given; clearing
/etc/network/interfaces
Feb  9 06:32:45 netcfg[6883]: DEBUG: Writing informative header
Feb  9 06:32:45 netcfg[6883]: DEBUG: Success!
Feb  9 06:32:45 netcfg[6883]: DEBUG: Writing loopback interface
Feb  9 06:32:45 netcfg[6883]: DEBUG: Success!
Feb  9 06:32:45 netcfg[6883]: DEBUG: Writing DHCP stanza for wlp2s0
Feb  9 06:32:45 netcfg[6883]: INFO: Detected wlp2s0 as a hotpluggable device
Feb  9 06:32:45 netcfg[6883]: DEBUG: Writing SLAAC stanza for wlp2s0
Feb  9 06:32:45 netcfg[6883]: DEBUG: Writing wireless options for wlp2s0
Feb  9 06:32:45 netcfg[6883]: DEBUG: Success!

but the second attempt in finish-install.d only writes the loopback

Feb  9 07:27:06 finish-install: info: Running
/usr/lib/finish-install.d/55netcfg-copy-config
Feb  9 07:27:06 netcfg[30397]: INFO: Starting netcfg v.1.141
Feb  9 07:27:06 netcfg[30397]: DEBUG: No interface given; clearing
/etc/network/interfaces
Feb  9 07:27:06 netcfg[30397]: DEBUG: Writing informative header
Feb  9 07:27:06 netcfg[30397]: DEBUG: Success!
Feb  9 07:27:06 netcfg[30397]: DEBUG: Writing loopback interface
Feb  9 07:27:06 netcfg[30397]: DEBUG: Success!
Feb  9 07:27:06 finish-install: info: Running
/usr/lib/finish-install.d/60cleanup

I think the code to blame is here

https://anonscm.debian.org/cgit/d-i/netcfg.git/tree/finish-install.d/55netcfg-copy-config#n42

> # Check for preseeding. If the value of the question is empty then set
> # default options. Document automatic selection changes in the template.
> if [ -z "$RET" ]; then
> 	if $NM_IS_INSTALLED; then
> 		db_set netcfg/target_network_config $CONFIG_NM
> 	else
> 		if [ "$NETCFG_CONNECTION_TYPE" = "wired" ]; then
> 			db_set netcfg/target_network_config $CONFIG_INTERFACES
> 		else # wireless
> 			db_set netcfg/target_network_config $CONFIG_LOOPBACK
> 		fi
> 	fi
> fi

in finish-install /e/n/i will never be properly populated for a wireless
installation without network-manager, although I think ifupdown would be
capable to do this (not tested, but have a look at
https://anonscm.debian.org/cgit/d-i/netcfg.git/tree/write_interface.c).
I guess the justification is that people using wireless usually would
want a GUI to roam between networks, and a interface stanza would
prevent even a (later installed) network-manager from touching the
interface.

rdnssd just triggers this more often because it will prevent
network-manager installations on the desktop tasks normally using the
wireless connectivity.

But, all in all, I think network-manager should take precedence over
rdnssd. So we can either

a) go for Cyril's suggestion and just install rdnssd in finish-install
if network-manager is not getting installed there (but honestly I have
no idea of the netcfg code base)
b) drop the Conflicts and make the rdnssd merge-hook a no-op if
network-manager is installed/running.

Bernhard