vip_watchdog

#!/bin/bash

#**
#
# Simple watchdog to manage BGP announces (with Quagga/BGPd) vs. realservers states (with Keepalived)
# - a VIP which has equal or less than DROP_ROUTE_THRESHOLD members will be un-announced on the network
# - a VIP which has equal or more than REST_ROUTE_THRESHOLD members will be re-announced on the network
# 
# @date 2012
# @author pcheynier
#
# Limitations : 
# - VIPs hosting multiples services (ports) may be announced because only ONE of the services is down. 
#
#**

# Require the BGP toolkit
source /usr/local/bin/scripts/bgp.inc.sh

# --------- CONFIGURATION

# ipvsadm Path
IPVSADM="/sbin/ipvsadm"

# Default masks used to add/remove a route announce
BGP_ANNOUNCE_MASK_V4="32"
BGP_ANNOUNCE_MASK_V6="128"

# Minimal number of operational realservers to unanounce the VIP
DROP_ROUTE_THRESHOLD=0

# Minimal number of operational realservers to reanounce the VIP
REST_ROUTE_THRESHOLD=1

# --------- END OF CONF

# Check user and running processes
if [ "`id -u -n`" != "root" ]; then
        echo "Only run as root !"
        exit 255;
fi
if [ -z "`pidof bgpd`" ]; then
        echo "fatal error : quagga/bgpd not running !"
        exit 255;
fi
if [ -z "`pidof keepalived`" ]; then
        echo "fatal error : keepalived not running !"
        exit 255;
fi

# Check for needed operations
for VSERVER in `$IPVSADM -L -n | tail -n +4 | grep -v '^  ->' | awk '{ printf "%s,%s\n",$1,$2 }'`; do

    PROTO=`echo $VSERVER | cut -d',' -f1`
    VIP=`echo $VSERVER | cut -d',' -f2`
    if [ $PROTO == "UDP" ]; then IPVSADM_PROTO_SWITCH="-u"; else IPVSADM_PROTO_SWITCH="-t"; fi;

    # Get the number of real_server behind each VIP
    NB_REALSERVERS=`$IPVSADM -L -n $IPVSADM_PROTO_SWITCH $VIP | tail -n +4 | grep '^  ->' | wc -l`;

    # Check if this route is announced
    if is_v6 $VIP; then 
        BGP_ANNOUNCE_MASK=${BGP_ANNOUNCE_MASK_V6}
    else 
        BGP_ANNOUNCE_MASK=${BGP_ANNOUNCE_MASK_V4}
    fi
    VIP_NET="`echo $VIP | tr -d '[]' | rev | cut -d':' -f2- | rev`/${BGP_ANNOUNCE_MASK}"
    check_route $VIP_NET
    ROUTE_PRESENCE=$?
    # Check if we need to do something
    if [[ $NB_REALSERVERS -le $DROP_ROUTE_THRESHOLD ]] && [[ $ROUTE_PRESENCE -eq 0 ]]; then
        # There is equal or less than DROP_ROUTE_THRESHOLD, we need to remove the route
        remove_route "$VIP_NET"
    elif [[ $NB_REALSERVERS -ge $REST_ROUTE_THRESHOLD ]] && [[ $ROUTE_PRESENCE -eq 1 ]]; then
        # There is equal or more than REST_ROUTE_THRESHOLD, we need to add the route
        add_route "$VIP_NET"
    fi

done

exit 0;