adding ifmetric that was accidentally left out

Change-Id: I591e2fe976b35b9fca8ab8ef78f76822b96841bf

contrib/image-elements/ifmetric/post-install.d/90-ifmetric

@@ -0,0 +1,35 @@
+#!/bin/bash
+
+set -eux
+
+install-packages ifmetric
+
+cat <<EOF > /etc/network/interfaces
+# The loopback network interface
+auto lo
+iface lo inet loopback
+
+source /etc/network/interfaces.d/*
+EOF
+
+mkdir -p /etc/network/interfaces.d
+rm /etc/network/interfaces.d/*
+
+cat <<EOF > /etc/network/interfaces.d/eth0
+# The primary network interface
+allow-hotplug eth0
+iface eth0 inet dhcp
+    metric 0
+EOF
+
+cat <<EOF > /etc/network/interfaces.d/eth1
+allow-hotplug eth1
+iface eth1 inet dhcp
+    metric 1
+EOF
+
+cat <<EOF > /etc/network/interfaces.d/eth2
+allow-hotplug eth2
+iface eth2 inet dhcp
+    metric 2
+EOF