MySQL and Galera Load Balancer (GLB)

#!/bin/sh
#
# glbd          Start/Stop the Galera Load Balancer daemon.
#
# processname: glbd
# chkconfig: 2345 90 60
# description: GLB is a TCP load balancer similar to Pen. \
#              It lacks most of advanced Pen features, as \
#              the aim was to make a user-space TCP proxy which is \
#              as fast as possible. It can utilize multiple CPU cores. \
#              A list of destinations can be configured at runtime. \
#              Destination "draining" is supported. It features \
#              weight-based connection balancing (which becomes \
#              round-robin if weights are equal).

### BEGIN INIT INFO
# Provides: glbd
# Required-Start: $local_fs
# Required-Stop: $local_fs
# Default-Start:  2345
# Default-Stop: 90
# Short-Description: run glbd daemon
# Description: GLB is a TCP load balancer similar to Pen.
### END INIT INFO

prog="glbd"
proc=glbd
exec=/usr/sbin/glbd

LISTEN_PORT="8010"
CONTROL_PORT="8011"
THREADS="2"
DEFAULT_TARGETS="djdb2:8000:0.75 djdb3:8000:0.75 divjobs3:8000:0.75 divjobs4:8000:1"

stop() {
  echo -n "[`date`] $prog: stopping... "
  killall $exec &> /dev/null
  if [ $? -ne 0 ]; then
    echo "failed."
    return
  fi
  echo "done."
}

start() {
  if pidof $prog &> /dev/null ; then
    echo "[`date`] $prog: already running...";
    exit -1
  fi
  echo "[`date`] $prog: starting..."
  wait_for_connections_to_drop
  $exec --daemon --control 127.0.0.1:$CONTROL_PORT --threads $THREADS $LISTEN_PORT $DEFAULT_TARGETS
  PID=$!
  if [ $? -ne 0 ]; then
    echo "[`date`] $prog: failed to start."
    exit -1
  fi
  echo "[`date`] $prog: started, pid=$PID"
  exit 0
}

restart() {
  echo "[`date`] $prog: restarting..."
  stop
  start
}

wait_for_connections_to_drop() {
  while (netstat -na | grep -m 1 ":$LISTEN_PORT" &> /dev/null); do
    echo "[`date`] $prog: waiting for lingering sockets to clear up..."
    sleep 1s
  done;
}

getinfo() {
  echo getinfo | nc 127.0.0.1 $CONTROL_PORT && exit 0
  echo "[`date`] $prog: failed to query 'getinfo' from 127.0.0.1:$CONTROL_PORT"
  exit -1
}

getstats() {
  echo getstats | nc 127.0.0.1 $CONTROL_PORT && exit 0
  echo "[`date`] $prog: failed to query 'getstats' from 127.0.0.1:$CONTROL_PORT"
  exit -1
}

add() {
  if [ "$1" == "" ]; then
    echo $"Usage: $0 add :[:]"
    exit -1
  fi
  if [ "`echo "$1" | nc 127.0.0.1 $CONTROL_PORT`" == "Ok" ]; then
    echo "[`date`] $prog: added '$1' successfully"
    #getinfo
    exit 0
  fi
  echo "[`date`] $prog: failed to add target '$1'."
  exit -1
}

remove() {
  if [ "$1" == "" ]; then
    echo $"Usage: $0 remove :"
    exit -1
  fi
  if [ "`echo "$1:-1" | nc 127.0.0.1 $CONTROL_PORT`" == "Ok" ]; then
    echo "[`date`] $prog: removed '$1' successfully"
    #getinfo
    exit 0
  fi
  echo "[`date`] $prog: failed to remove target '$1'."
  exit -1
}

case $1 in
  start)
    start
  ;;
  stop)
    stop
  ;;
  restart)
    restart
  ;;
  getinfo)
    getinfo
  ;;
  getstats)
    getstats
  ;;
  status)
    getinfo
  ;;
  add)
    add $2
  ;;
  remove)
    remove $2
  ;;
  *)
    echo $"Usage: $0 {start|stop|restart|status|getstats|getinfo|add|remove}"
  exit 2
esac