update-neutron-dvr-fip-garp.sh

#!/bin/bash -eux
# Origin: https://gist.github.com/dosaboy/37121dcfd6581066cec8f6377817a4ef
#
# Authors:
#   - edward.hope-morley@canonical.com
#
# Description:
#   Send a gratuitous arp for every floating ip in use on a node. Uses same
#   method to send garp as neutron.

# Create set of FIPs in use on this node
declare -a fips=()
for ns in `find /var/run/netns/ -name qrouter-\*`; do
    ns=`basename $ns`
    readarray -t _fips<<<"`sudo ip netns exec $ns iptables -t nat -S| egrep "SNAT\s--to-source"| awk '{print $NF}'`"
    ((${#_fips[@]}==0)) || [ -z "${_fips[0]}" ] && continue
    fips+=( ${_fips[@]} )
done

# Find corresponding fip ns for each FIP
declare -A fip_ns_index=()
for ns in `find /var/run/netns/ -name fip-\*`; do
    ns=`basename $ns`
    for fip in ${fips[@]}; do
        # of the fip is actually connected to this fip ns it will have a route to a qrouter ns via an fpr interface
        if `sudo ip netns exec $ns ip r get $fip| grep -q fpr-`; then
            fip_ns_index[$fip]=$ns
        fi
    done
done

# Send garp for each FIP
for fip in ${!fip_ns_index[@]}; do
    # there should only ever be one fg- interface per fip ns
    ns=${fip_ns_index[$fip]}
    fg_iface=`sudo ip netns exec $ns ip -br a| awk '{print $1}'| grep fg-`
    sudo ip netns exec $ns arping -A -I $fg_iface -c 1 -w 1.5 $fip
    sudo ip netns exec $ns arping -U -I $fg_iface -c 1 -w 1.5 $fip
done