/etc/init/network-interface.conf uses ifconfig, should use "ip" instead since ifconfig is deprecated..

As the summary says
/etc/init/network-interface.conf uses ifconfig but it should use "ip" instead:

This is the line:
ifconfig lo 127.0.0.1 up || true
It probably should be:
ip link set dev lo up || true

This command fails on a clean minimal ubuntu install since net-tools that provides ifconfig isn't installed.

There should be no need to set ip while bringing the interface up (which could interfere with future ipv4-only or ipv6-only setups) as the kernel configures it automatically.

----

cat /etc/init/network-interface.conf
# network-interface - configure network device
#
# This service causes network devices to be brought up or down as a result
# of hardware being added or removed, including that which isn't ordinarily
# removable.

description "configure network device"

emits net-device-up
emits net-device-down
emits static-network-up

start on net-device-added
stop on net-device-removed INTERFACE=$INTERFACE

instance $INTERFACE
export INTERFACE

pre-start script
    if [ "$INTERFACE" = lo ]; then
        # bring this up even if /etc/network/interfaces is broken
        ifconfig lo 127.0.0.1 up || true
        initctl emit -n net-device-up \n IFACE=lo LOGICAL=lo ADDRFAM=inet METHOD=loopback || true
    fi
    mkdir -p /run/network
    exec ifup --allow auto $INTERFACE
end script

post-stop exec ifdown --force --allow auto $INTERFACE