sonic-buildimage/files/image_config/interfaces/interfaces-config.sh

#!/bin/bash

if [[ $(ifquery --running eth0) ]]; then
    ifdown --force eth0
fi

# Check if ZTP DHCP policy has been installed
if [ -e /etc/network/ifupdown2/policy.d/ztp_dhcp.json ]; then
    # Obtain port operational state information
    redis-dump -d 0 -k "PORT_TABLE:Ethernet*"  -y > /tmp/ztp_port_data.json

    if [ $? -ne 0 ] || [ ! -e /tmp/ztp_port_data.json ] || [ "$(cat /tmp/ztp_port_data.json)" = "" ]; then
        echo "{}" > /tmp/ztp_port_data.json
    fi

    # Create an input file with ztp input information
    echo "{ \"PORT_DATA\" : $(cat /tmp/ztp_port_data.json) }" > \
          /tmp/ztp_input.json
else
    echo "{ \"ZTP_DHCP_DISABLED\" : \"true\" }" > /tmp/ztp_input.json
fi

# Create /e/n/i file for existing and active interfaces, dhcp6 sytcl.conf and dhclient.conf
CFGGEN_PARAMS=" \
    -d -j /tmp/ztp_input.json \
    -t /usr/share/sonic/templates/interfaces.j2,/etc/network/interfaces \
    -t /usr/share/sonic/templates/90-dhcp6-systcl.conf.j2,/etc/sysctl.d/90-dhcp6-systcl.conf \
    -t /usr/share/sonic/templates/dhclient.conf.j2,/etc/dhcp/dhclient.conf \
"
sonic-cfggen $CFGGEN_PARAMS

[ -f /var/run/dhclient.eth0.pid ] && kill `cat /var/run/dhclient.eth0.pid` && rm -f /var/run/dhclient.eth0.pid
[ -f /var/run/dhclient6.eth0.pid ] && kill `cat /var/run/dhclient6.eth0.pid` && rm -f /var/run/dhclient6.eth0.pid

for intf_pid in $(ls -1 /var/run/dhclient*.Ethernet*.pid 2> /dev/null); do
    [ -f ${intf_pid} ] && kill `cat ${intf_pid}` && rm -f ${intf_pid}
done


# Setup eth1 if we connect to a remote chassis DB.
PLATFORM=${PLATFORM:-`sonic-cfggen -H -v DEVICE_METADATA.localhost.platform`}
CHASSISDB_CONF="/usr/share/sonic/device/$PLATFORM/chassisdb.conf"
[ -f $CHASSISDB_CONF ] && source $CHASSISDB_CONF

ASIC_CONF="/usr/share/sonic/device/$PLATFORM/asic.conf"
[ -f $ASIC_CONF ] && source $ASIC_CONF

if [[ -n "$midplane_subnet" && ($NUM_ASIC -gt 1) ]]; then
    for asic_id in `seq 0 $((NUM_ASIC - 1))`; do
       NET_NS="asic$asic_id"

       PIDS=`ip netns pids "$NET_NS" 2>/dev/null`
       if [ "$?" -ne "0" ]; then # namespace doesn't exist
          continue
       fi

       # Use /16 for loopback interface
       ip netns exec $NET_NS ip addr add 127.0.0.1/16 dev lo
       ip netns exec $NET_NS ip addr del 127.0.0.1/8 dev lo

       # Create eth1 in database instance
       ip link add name ns-eth1 link eth1-midplane type ipvlan mode l2
       ip link set dev ns-eth1 netns $NET_NS
       ip netns exec $NET_NS ip link set ns-eth1 name eth1

       # Configure IP address and enable eth1
       lc_slot_id=$(python3 -c 'import sonic_platform.platform; platform_chassis = sonic_platform.platform.Platform().get_chassis(); print(platform_chassis.get_my_slot())' 2>/dev/null)
       lc_ip_address=`echo $midplane_subnet | awk -F. '{print $1 "." $2}'`.$lc_slot_id.$((asic_id + 10))
       lc_subnet_mask=${midplane_subnet#*/}
       ip netns exec $NET_NS ip addr add $lc_ip_address/$lc_subnet_mask dev eth1
       ip netns exec $NET_NS ip link set dev eth1 up

       # Allow localnet routing on the new interfaces if midplane is using a
       # subnet in the 127/8 range.
       if [[ "${midplane_subnet#127}" != "$midplane_subnet" ]]; then
          ip netns exec $NET_NS bash -c "echo 1 > /proc/sys/net/ipv4/conf/eth1/route_localnet"
       fi
    done
fi

# Read sysctl conf files again
sysctl -p /etc/sysctl.d/90-dhcp6-systcl.conf

systemctl restart networking

# Clean-up created files
rm -f /tmp/ztp_input.json /tmp/ztp_port_data.json