unifi-sensu-agent-init

#!/bin/sh
### BEGIN INIT INFO
# Provides:          sensu-agent
# Required-Start:    $remote_fs $syslog
# Required-Stop:     $remote_fs $syslog
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Start sensu-agent
# Description:       Enable the Sensu Agent service
### END INIT INFO

PATH=/sbin:/usr/sbin:/bin:/usr/bin
export PATH

name=sensu-agent
program=/usr/sbin/sensu-agent
args="start"
pidfile="/var/run/sensu/$name.pid"
user="sensu"
group="sensu"
chroot="/"
chdir="/"
nice=""


# If this is set to 1, then when `stop` is called, if the process has
# not exited within a reasonable time, SIGKILL will be sent next.
# The default behavior is to simply log a message "program stop failed; still running"
KILL_ON_STOP_TIMEOUT=0

# Maximum number of open file descriptors.
MAX_OPEN_FILES=65535

# When loading default and sysconfig files, we use `set -a` to make
# all variables automatically into environment variables.
set -a
[ -r /etc/default/sensu-agent ] && . /etc/default/sensu-agent
[ -r /etc/sysconfig/sensu-agent ] && . /etc/sysconfig/sensu-agent
set +a

[ -z "$nice" ] && nice=0

trace() {
  logger -t "/etc/init.d/sensu-agent" "$@"
}

emit() {
  trace "$@"
  echo "$@"
}

start() {
  ulimit -n ${MAX_OPEN_FILES}

  # Setup any environmental stuff beforehand


  # Run the program!
  set +e
  chroot 2>&1 | grep BusyBox > /dev/null
  RC=$?
  set -e
  if [ "$RC" -eq 0 ] ; then
    start-stop-daemon -S -q -c $user -b -m \
      -p $pidfile -x $program -- $args \
      >> /var/log/sensu/sensu-agent.log 2>&1
  else
    chroot --userspec "$user":"$group" "$chroot" sh -c "
      cd \"$chdir\"
      ulimit -n ${MAX_OPEN_FILES}
      exec \"$program\" $args
      " >> /var/log/sensu/sensu-agent.log 2>&1 &
  fi

  # Generate the pidfile from here. If we instead made the forked process
  # generate it there will be a race condition between the pidfile writing
  # and a process possibly asking for status.
  echo $! > $pidfile

  emit "$name started"
  return 0
}

stop() {
  # Try a few times to kill TERM the program
  if status ; then
    pid=$(cat "$pidfile")
    trace "Killing $name (pid $pid) with SIGTERM"
    kill -TERM $pid
    # Wait for it to exit.
    for i in 1 2 3 4 5 ; do
      trace "Waiting $name (pid $pid) to die..."
      status || break
      sleep 1
    done
    if status ; then
      if [ "$KILL_ON_STOP_TIMEOUT" -eq 1 ] ; then
	trace "Timeout reached. Killing $name (pid $pid) with SIGKILL.  This may result in data loss."
	kill -KILL $pid
	emit "$name killed with SIGKILL."
      else
	emit "$name stop failed; still running."
      fi
    else
      emit "$name stopped."
    fi
  fi
}

status() {
  if [ -f "$pidfile" ] ; then
    pid=$(cat "$pidfile")
    if ps -p $pid > /dev/null 2> /dev/null ; then
      # process by this pid is running.
      # It may not be our pid, but that's what you get with just pidfiles.
      # TODO(sissel): Check if this process seems to be the same as the one we
      # expect. It'd be nice to use flock here, but flock uses fork, not exec,
      # so it makes it quite awkward to use in this case.
      return 0
    else
      return 2 # program is dead but pid file exists
    fi
  else
    return 3 # program is not running
  fi
}

force_stop() {
  if status ; then
    stop
    status && kill -KILL $(cat "$pidfile")
  fi
}


case "$1" in
  force-start|start|stop|force-stop|restart)
    trace "Attempting '$1' on sensu-agent"
    ;;
esac

case "$1" in
  force-start)
    PRESTART=no
    exec "$0" start
    ;;
  start)
    status
    code=$?
    if [ $code -eq 0 ]; then
      emit "$name is already running"
      exit $code
    else
      start
      exit $?
    fi
    ;;
  stop) stop ;;
  force-stop) force_stop ;;
  status)
    status
    code=$?
    if [ $code -eq 0 ] ; then
      emit "$name is running"
    else
      emit "$name is not running"
    fi
    exit $code
    ;;
  restart)

    stop && start
    ;;
  *)
    echo "Usage: $SCRIPTNAME {start|force-start|stop|force-start|force-stop|status|restart}" >&2
    exit 3
  ;;
esac

exit $?