MAAS Server ISO install fails when network is disconnected

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/1172566

I am marking this medium, as I think it is a marginal use case of people that would want to install a network dependant application, without a network.

Thanks.

Issue confirmed on Trusty daily ISO.

More detail, see also attached tarball:
Apr 14 17:26:05 in-target: dpkg: error processing package maas-region-controller-min (--configure):
Apr 14 17:26:05 in-target: subprocess installed post-installation script returned error exit status 255
Apr 14 17:26:05 in-target: dpkg: dependency problems prevent configuration of maas-region-controller:
Apr 14 17:26:05 in-target: maas-region-controller depends on maas-region-controller-min (= 1.5+bzr2236-0ubuntu1); however:
Apr 14 17:26:05 in-target: Package maas-region-controller-min is not configured yet.
Apr 14 17:26:05 in-target:
Apr 14 17:26:05 in-target: dpkg: error processing package maas-region-controller (--configure):
Apr 14 17:26:05 in-target: dependency problems - leaving unconfigured
Apr 14 17:26:05 in-target: dpkg: dependency problems prevent configuration of maas:
Apr 14 17:26:05 in-target: maas depends on maas-region-controller; however:
Apr 14 17:26:05 in-target: Package maas-region-controller is not configured yet.
Apr 14 17:26:05 in-target:
Apr 14 17:26:05 in-target: dpkg: error processing package maas (--configure):
Apr 14 17:26:05 in-target: dependency problems - leaving unconfigured
Apr 14 17:26:05 in-target: dpkg: dependency problems prevent configuration of maas-dns:
Apr 14 17:26:05 in-target: maas-dns depends on maas-region-controller-min (= 1.5+bzr2236-0ubuntu1); however:
Apr 14 17:26:05 in-target: Package maas-region-controller-min is not configured yet.
Apr 14 17:26:05 in-target:
Apr 14 17:26:05 in-target: dpkg: error processing package maas-dns (--configure):
Apr 14 17:26:05 in-target: dependency problems - leaving unconfigured
Apr 14 17:26:05 in-target: Errors were encountered while processing:
Apr 14 17:26:05 in-target: maas-region-controller-min
Apr 14 17:26:05 in-target: maas-region-controller
Apr 14 17:26:05 in-target: maas
Apr 14 17:26:05 in-target: maas-dns
Apr 14 17:26:06 main-menu[220]: WARNING **: Configuring 'pkgsel' failed with error code 100
Apr 14 17:26:06 main-menu[220]: WARNING **: Menu item 'pkgsel' failed.

so the bug here is actually in 'get_default_route_ip' of the postinst for maas-region-controller-min and maas-region-controller.

They run with 'set -e' (which i'm never a fan of), and then have:

get_default_route_ip() {
   while read Iface Destination Gateway Flags RefCnt Use Metric Mask MTU Window IRTT; do [ "$Mask" = "00000000" ] && break
   done < /proc/net/route
   interface="$Iface"
   ipaddr=$(LC_ALL=C /sbin/ip -4 addr list dev "$interface" scope global)
   ipaddr=${ipaddr#* inet }
   ipaddr=${ipaddr%%/*}
        echo $ipaddr
}

That method has many issues.
a.) will stomp over global variables 'iface' 'Destination' Gateway, Flags .... and 'interface'. luckily it is only run in a subshell, so thats not really a problem here.
b.) if interface is empty it runs : ip -4 addr list dev "" scope global

ip fails, thus the method fails, and thus the dpkg postinst fails (thanks to set -e).

the simpllist fix is just to add:
 [ -n "$interface" ] || return 0

right after the loop that reads /proc/net/route.

fix in lp:~smoser/ubuntu/trusty/maas/lp-1172566.

Thanks, Scott. Further confirmation:

In previous no-network MAAS tests, the environment had no default gateway set.

So, the missing dependency claim is debunked. This is not a dependency, nor an ISO issue. Dependencies are indeed met on the Trusty ISO.

I confirmed this by successful installation of MAAS from ISO on a machine with a fully configured ip interface, but with no internet access.

The 'no-network MAAS install failure' issue that we're seeing is specifically caused by having no default gateway set.