metrics.sh/metrics/disk_io.sh

#!/bin/sh

init () {
  if [ -z $DISK_IO_MOUNTPOINT ]; then
    if is_osx; then
      DISK_IO_MOUNTPOINT="disk0"
    else
      DISK_IO_MOUNTPOINT="/dev/vda"
    fi
  fi
  readonly __disk_io_fifo=$TEMP_DIR/disk_io
  mkfifo $__disk_io_fifo
  __disk_io_bgproc &
}

if is_osx; then
  __disk_io_bgproc () {
    iostat -K -d -w $INTERVAL $DISK_IO_MOUNTPOINT | while read line; do
      echo $line | awk '{ print $3 }' > $__disk_io_fifo
    done
  }
else
  __disk_io_bgproc () {
    echo $(iostat -y -d 1 $DISK_IO_MOUNTPOINT)
  }
fi

collect () {
  report $(cat $__disk_io_fifo)
}

terminate () {
  if [ ! -z $__disk_io_fifo ] && [ -p $__disk_io_fifo ]; then
    rm $__disk_io_fifo
  fi
}

docs () {
  echo "Disk I/O in MB/s."
  echo "\$DISK_IO_MOUNTPOINT="
}