_ なんちゃって

fakeなvrrpdは、マスターの応答をタイムアウト1秒のpingで見てるので、 高負荷などで応答が滞った時にパタパタ（flap）しないようにちょっと手を入れた。 　

#!/bin/sh
# This is "Fake VRRP daemon"
# Ver 1.03
# By H.Uekusa 20200716
# Put "fakevrrpd" into /usr/local/etc/rc.d
# such as below
# and do
# "service fakevrrpd enable"
# "service fakevrrpd enabled"
# "service fakevrrpd start"
#---------------------from here-----------------------
# #!/bin/sh
# # -*- coding: utf-8; mode: shell-script; -*-
# # insert `fakevrrpd_enable="YES"' in /etc/rc.conf
# # Use with fvrrpd
# # By H.Uekusa 20200630
# #
# # PROVIDE: fakevrrpd
#
# PROG="/usr/local/etc/fvrrpd"
#
# . /etc/rc.subr
#
# name=fakevrrpd
# rcvar=fakevrrpd_enable
# procname=/bin/sh
# pidfile=/var/run/fvrrpd.pid
#
# start_cmd="${name}_start"
# stop_cmd="${name}_stop"
#
# load_rc_config $name
# : ${fakevrrpd_enable:="NO"}
#
# fakevrrpd_start () {
#         echo "Starting fakevrrpd"
#         $PROG -d
# }
#
# fakevrrpd_stop () {
#         echo "Stopping fakevrrpd"
#         $PROG -k
# }
#
# run_rc_command "$1"
#-----------------------to here-----------------------
#
############### configuration valiables ################
CAT="/bin/cat"
GREP="/usr/bin/grep"
IFCONFIG="/sbin/ifconfig"
KILLA="/usr/bin/killall"
LOGGER="/usr/bin/logger"
PING="/sbin/ping"
NC="/usr/bin/nc -z -w 1 "
RESTART_NAMED="/usr/sbin/service named restart"
#
VIP="192.168.10.100"
MASK="netmask 255.255.255.0"
MASTER="192.168.10.10" #Actual master IP address
IF="em0" #Physical interface name in ifconfig
TIMEOUT="3" # Timeout for ping (Seconds)
PORT="80" #Monitor port number for back up the master
WAIT_LIMIT="60" #Limit for waiting the service port (Seconds)
DOUBLE_CHECK="YES" #Double check for Master down (YES/NO)
CHECK_LOOPNUM="4" #Number of loop for double check
CHECK_INTERVAL="2" #Sleep time for double check (Seconds)
#
PIDFILE="/var/run/fvrrpd.pid" #It must be same configuration with fakevrrpd in rc.d.
LOGNAME="fake_vrrpd" #Name on the messages
########################################################
################### main procedure #####################
main () {
STAT_PREV="0"
PID=`echo $$`
echo $PID > $PIDFILE
#
if [ "$1" == "verbose" ];then
        LOG="echo"
elif [ "$1" == "daemon" ];then
        LOG=`echo $LOGGER -is -t $LOGNAME`
else
        exit 3
fi
#
$LOG "Fake vrrpd PID is $PID"
#
while [ 1 ]; do #Infinite loop
$PING -c1 -t$TIMEOUT $MASTER >/dev/null 2>&1
STAT_NOW=`echo $?`
        if [ $STAT_NOW != $STAT_PREV ];then #Found change
                if [ $STAT_NOW != 0 ];then #Change is master down
                        if [ "$DOUBLE_CHECK" == "YES" ];then # Do double check
                                LOOP_COUNT="0"
                                while [ $LOOP_COUNT -lt $CHECK_LOOPNUM ];do
                                        $PING -c1 -t$TIMEOUT $MASTER >/dev/null 2>&1
                                        STAT_DOUBLE=`echo $?`
                                        LOOP_COUNT=`expr $LOOP_COUNT + 1`
                                        sleep $CHECK_INTERVAL
                                done
                        else
                                STAT_DOUBLE=1
                        fi
                        if [ $STAT_DOUBLE != 0 ];then # Double check is fail
                                $LOG "Master $MASTER down detected! I will become the Master"
                                $IFCONFIG $IF |$GREP $VIP >/dev/null 2>&1
                                MY_VIP_ENABLED=`echo $?`
                                if [ $MY_VIP_ENABLED != 0 ];then #My VIP is not set
                                        $PING -c1 -t$TIMEOUT $VIP >/dev/null 2>&1
                                        STAT_VIP=`echo $?`
                                        if [ $STAT_VIP != 0 ];then #Another VIP is not found
                                                $LOG "I become the Master!"
                                                $IFCONFIG $IF alias $VIP $MASK
                                                $LOG "Restarting named"
                                                $RESTART_NAMED
                                        else
                                                $LOG "The Master seems down, but there is another Master ??"
                                                $LOG "To avoid conflict, do nothing."
                                        fi
                                else
                                        $LOG "I am already the Master? Do nothing."
                                fi
                        else
                                $LOG "Master $MASTER flapped, But baked up now."
                        fi
                else #Change is master back up
                        $LOG "Master $MASTER interface back up detected! Waiting for enabling service at $PORT."
                        NC_STAT="1"
                        STAT_COUNT="0"
                        while [ $NC_STAT != 0 ];do
                                $NC $MASTER $PORT
                                NC_STAT=`echo $?`
                                echo "Status $NC_STAT"
                                echo "Count $STAT_COUNT"
                                if [ $STAT_COUNT -gt $WAIT_LIMIT ];then
                                        $LOG "Waiting for enabling service at $PORT timed out $WAIT_LIMIT sec, aborting."
                                        $IFCONFIG $IF |$GREP $VIP >/dev/null 2>&1
                                        MY_VIP_ENABLE=`echo $?`
                                        if [ $MY_VIP_ENABLE = 0 ];then #My VIP was set
                                                $LOG "Removing alias $VIP for master"
                                                $IFCONFIG $IF -alias $VIP
                                        else
                                                $LOG "VIP $VIP is already removed or not set, Nothing to do."
                                        fi
                                        $LOG "Restarting named"
                                        $RESTART_NAMED
                                        rm -f $PIDFILE
                                        exit 5
                                fi
                                STAT_COUNT=`expr $STAT_COUNT + 1`
                                sleep 1
                        done
                        $LOG "Master $MASTER service back up detected! I will become the standby"
                        $IFCONFIG $IF |$GREP $VIP >/dev/null 2>&1
                        MY_VIP_ENABLE=`echo $?`
                        if [ $MY_VIP_ENABLE = 0 ];then #My VIP was set
                                $LOG "I become the standby! Removing alias $VIP"
                                $IFCONFIG $IF -alias $VIP
                                $LOG "Restarting named"
                                $RESTART_NAMED
                        else
                                $LOG "VIP $VIP is already removed or not set, Nothing to do."
                        fi
                fi
        fi
echo "IF Status $STAT_PREV->$STAT_NOW"
STAT_PREV=`echo $STAT_NOW`
sleep 1
done
rm -f $PIDFILE
exit 4
}
########################################################
############## check arguments and execute #############
if [ "$1" == "-d" ];then #Run as daemon
        LOG=`echo $LOGGER -is -t $LOGNAME`
        $LOG "Fake vrrpd is starting as daemon"
        if [ -f "$PIDFILE" ];then #Exist PID file?
                $LOG "There is PID file at $PIDFILE,I'm exiting"
                $LOG "If you would like to start forcibly, Use -k option first"
                exit 2
        fi
        $0 -vd >/dev/null 2>&1 &
elif [ "$1" == "-h" ];then #Display help
        echo "Usage"
        echo " -d : Run as daemon"
        echo " -h : Display help"
        echo " -v : Run on foreground"
        echo " -k : Kill daemon"
elif [ "$1" == "-k" ];then #Killing existing process
        LOG=`echo $LOGGER -is -t $LOGNAME`
        if [ -f "$PIDFILE" ];then #Exist PID file?
                PIDKILL=`$CAT $PIDFILE`
                $LOG "Killing fake vrrpd $PIDKILL"
                kill -9 $PIDKILL
                rm -f $PIDFILE
                $LOG "removing PID file"
        else
                $LOG "PID file not found, killing with killall"
                $KILLA $0
        fi
        $IFCONFIG $IF |$GREP $VIP >/dev/null 2>&1
        MY_VIP_ENABLE=`echo $?`
        if [ $MY_VIP_ENABLE = 0 ];then #My VIP was set
                $LOG "Removing alias $VIP for master"
                $IFCONFIG $IF -alias $VIP
        else
                $LOG "VIP $VIP is already removed or not set, Nothing to do."
        fi
        $LOG "Restarting named"
        $RESTART_NAMED
        exit 1
elif [ "$1" == "-v" ];then #Run on foreground
        LOG="echo"
        if [ -f "$PIDFILE" ];then #Exist PID file?
                $LOG "There is PID file at $PIDFILE,I'm exiting"
                $LOG "If you would like to start forcibly, Use -k option first"
                exit 2
        fi
        main verbose
elif [ "$1" == "-vd" ];then #Run as daemon
        main daemon
else
        echo "Usage"
        echo " -d : Run as daemon"
        echo " -h : Display help"
        echo " -v : Run on foreground"
        echo " -k : Kill daemon"
fi
exit 0
########################################################