[DHCP_RELAY] Updated wait_for_intf.sh to wait for ipv6 global and link local addr

[vivekrnv]

Signed-off-by: Vivek Reddy Karri vkarri@nvidia.com

Why I did it

Fixes https://github.com/sonic-net/sonic-buildimage/issues/11431

How I did it

How to verify it

• Unit Tests
• Tested on a live device

root@r-lionfish-16:/home/admin# redis-cli -n 4 hgetall "DHCP_RELAY|Vlan10"
1) "dhcpv6_servers@"
2) "fc01:2000::1"
root@r-lionfish-16:/home/admin# redis-cli -n 4 hgetall "VLAN|Vlan10"
1) "vlanid"
2) "10"
3) "dhcpv6_servers@"
4) "fc02:2000::1"
root@r-lionfish-16:/home/admin# ip addr show Vlan10
137: Vlan10@Bridge: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9100 qdisc noqueue state UP group default qlen 1000
    link/ether 1c:34:da:1c:9f:00 brd ff:ff:ff:ff:ff:ff
    inet6 fc02:2000::2/24 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::1e34:daff:fe1c:9f00/64 scope link
       valid_lft forever preferred_lft forever
root@r-lionfish-16:/home/admin# systemctl restart dhcp_relay

Syslog:

Oct  4 03:41:44.255907 r-lionfish-16 INFO dhcp_relay#supervisord 2022-10-04 00:41:44,255 INFO spawned: 'start' with pid 18
Oct  4 03:41:44.256812 r-lionfish-16 INFO dhcp_relay#supervisord 2022-10-04 00:41:44,256 INFO success: start entered RUNNING state, process has stayed up for > than 0 seconds (startsecs)
Oct  4 03:41:44.269321 r-lionfish-16 INFO dhcp_relay#supervisord 2022-10-04 00:41:44,268 INFO exited: dhcpmon-Vlan10 (exit status 0; not expected)
Oct  4 03:41:44.504875 r-lionfish-16 INFO dhcp_relay#supervisord: start Waiting until interface Vlan10 is ready...
Oct  4 03:41:44.509125 r-lionfish-16 INFO dhcp_relay#supervisord: start Interface Vlan10 is ready!
Oct  4 03:41:44.509125 r-lionfish-16 INFO dhcp_relay#supervisord: start Waiting until interface Vlan10 has a link-local ipv6 address configured....
Oct  4 03:41:44.512623 r-lionfish-16 INFO dhcp_relay#supervisord: start Link-Local address is configured on Vlan10

root@r-lionfish-16:/home/admin# docker exec -it dhcp_relay cat /usr/bin/wait_for_intf.sh
#!/usr/bin/env bash
.............................

function check_for_ipv6_link_local
{
    IFACE_NAME=$1
    echo "Waiting until interface ${IFACE_NAME} has a link-local ipv6 address configured...."

    # Status of link local address is not populated in STATE_DB
    while true; do
        HAS_LL=$(ip -6 addr show ${IFACE_NAME} scope link 2> /dev/null)
        RC=$?
        if [[ ${RC} == "0" ]] && [[ ! -z ${HAS_LL} ]]; then
            break
        fi

        sleep 1
    done

    echo "Link-Local address is configured on ${IFACE_NAME}"
}

# dhcp6relay binds to ipv6 addresses configured on these vlan ifaces
# Thus check if they are ready before launching dhcp6relay
wait_until_iface_ready Vlan10 fc02:2000::2/24
check_for_ipv6_link_local Vlan10
..........

Negative Test: Remove link local address on Vlan iface and add it back

root@r-lionfish-16:/home/admin# ip addr del fe80::1e34:daff:fe1c:9f00/64 dev Vlan10
root@r-lionfish-16:/home/admin# ip addr show Vlan10
137: Vlan10@Bridge: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9100 qdisc noqueue state UP group default qlen 1000
    link/ether 1c:34:da:1c:9f:00 brd ff:ff:ff:ff:ff:ff
    inet6 fc02:2000::2/24 scope global
       valid_lft forever preferred_lft forever
root@r-lionfish-16:/home/admin# systemctl restart dhcp_relay

root@r-lionfish-16:/home/admin# show logging -f | grep dhcp_relay
Oct  4 03:51:54.661081 r-lionfish-16 INFO dhcp_relay#supervisord 2022-10-04 00:51:54,659 INFO spawned: 'start' with pid 20
Oct  4 03:51:54.661081 r-lionfish-16 INFO dhcp_relay#supervisord 2022-10-04 00:51:54,660 INFO success: start entered RUNNING state, process has stayed up for > than 0 seconds (startsecs)
Oct  4 03:51:54.662736 r-lionfish-16 INFO dhcp_relay#supervisord 2022-10-04 00:51:54,662 INFO exited: dhcpmon-Vlan10 (exit status 0; not expected)
Oct  4 03:51:54.895207 r-lionfish-16 INFO dhcp_relay#supervisord: start Waiting until interface Vlan10 is ready...
Oct  4 03:51:54.899206 r-lionfish-16 INFO dhcp_relay#supervisord: start Interface Vlan10 is ready!
Oct  4 03:51:54.899535 r-lionfish-16 INFO dhcp_relay#supervisord: start Waiting until interface Vlan10 has a link-local ipv6 address configured....


root@r-lionfish-16:/home/admin# docker exec -it dhcp_relay supervisorctl status
dependent-startup                RUNNING   pid 12, uptime 0:01:20

root@r-lionfish-16:/home/admin# ip addr add fe80::1e34:daff:fe1c:9f00/64 dev Vlan10 scope link
root@r-lionfish-16:/home/admin#
Oct  4 03:54:37.641777 r-lionfish-16 INFO dhcp_relay#supervisord: start Link-Local address is configured on Vlan10
Oct  4 03:54:47.644881 r-lionfish-16 INFO dhcp_relay#supervisord 2022-10-04 00:54:47,644 INFO exited: start (exit status 0; expected)
Oct  4 03:54:48.674002 r-lionfish-16 INFO dhcp_relay#supervisord 2022-10-04 00:54:48,672 INFO spawned: 'dhcp6relay' with pid 539
Oct  4 03:54:48.683344 r-lionfish-16 DEBUG dhcp_relay#dhcp6relay: key: Vlan10, Operation: SET, f: dhcpv6_servers, v: fc01:2000::1
Oct  4 03:54:49.693668 r-lionfish-16 INFO dhcp_relay#supervisord 2022-10-04 00:54:49,692 INFO success: dhcp6relay entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
Oct  4 03:54:50.763750 r-lionfish-16 INFO dhcp_relay#supervisord 2022-10-04 00:54:50,762 INFO exited: dependent-startup (exit status 0; expected)

root@r-lionfish-16:/home/admin# docker exec -it dhcp_relay supervisorctl status
dependent-startup                EXITED    Oct 04 12:54 AM
dhcp-relay:dhcp6relay            RUNNING   pid 539, uptime 0:00:52
........
start                            EXITED    Oct 04 12:54 AM

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205

Description for the changelog

Link to config_db schema for YANG module changes

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