dhclient doesn't honor metric setting in network interfaces on ubuntu 16.04

[Randy]

$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.1 LTS"

$ dpkg-query -l isc-dhcp-client
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-================================================================-=====================================-=====================================-======================================================================================================================================
ii isc-dhcp-client 4.3.3-5ubuntu12.6 amd64 DHCP client for automatically obtaining an IP address

# configure metric in network interface
$ cat /etc/network/interfaces.d/ens4.cfg
auto ens4
iface ens4 inet dhcp
  metric 1000

# dhclient set IF_METRIC=1000 environment variable for ens4
$ ps xau|egrep -i 'dhclient'
root 27906 0.0 0.0 16120 864 ? Ss 08:35 0:00 /sbin/dhclient -1 -v -pf /run/dhclient.ens3.pid -lf /var/lib/dhcp/dhclient.ens3.leases -I -df /var/lib/dhcp/dhclient6.ens3.leases ens3
root 28392 0.0 0.0 16120 868 ? Ss 08:59 0:00 /sbin/dhclient -1 -v -pf /run/dhclient.ens4.pid -lf /var/lib/dhcp/dhclient.ens4.leases -I -df /var/lib/dhcp/dhclient6.ens4.leases ens4 -e IF_METRIC=1000

$ route -nee
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface MSS Window irtt
0.0.0.0 xxx.xxx.xxx.xxx 0.0.0.0 UG 0 0 0 ens3 0 0 0
xxx.xxx.xxx.xxx 0.0.0.0 255.255.255.192 U 0 0 0 ens3 0 0 0
172.16.0.0 192.168.12.1 255.240.0.0 UG 0 0 0 ens4 0 0 0
192.168.0.0 192.168.12.1 255.255.0.0 UG 0 0 0 ens4 0 0 0
192.168.12.0 0.0.0.0 255.255.255.0 U 0 0 0 ens4 0 0 0

After ifdown ens4, ifup ens4, dhclient doens't configure metric for ens4 routes.

below patch fix this issue.

--- /etc/dhcp/dhclient-exit-hooks.d/rfc3442-classless-routes 2017-02-08 08:59:16.407956495 +0000
+++ ./rfc3442-classless-routes 2017-02-08 08:58:58.328337696 +0000
@@ -71,7 +71,7 @@

                                # set route (ip detects host routes automatically)
                                ip -4 route add "${net_address}/${net_length}" \
- ${via_arg} dev "${interface}" >/dev/null 2>&1
+ ${via_arg} dev "${interface}" ${IF_METRIC:+metric $IF_METRIC} >/dev/null 2>&1
                        done
                fi
        fi

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Stanislav Makar (smakar)]

ifmetric package will help you and patch is not needed anymore

sudo apt-get install ifmetric -y