Watch progress of a zpool (zfs) resilver — Python 3, Qt5

resilverprogress.py

#!/usr/bin/env python3

import re, subprocess, sys

from PyQt5.QtCore import Qt, QTimer
from PyQt5.QtWidgets import (
  QApplication,
  QWidget,
  QLabel,
  QProgressBar,
  QHBoxLayout,
  QVBoxLayout,
)

percent_re = re.compile(r'([\d.]+)%')
def get_status(pool):
  output = subprocess.check_output(['gksudo', 'zpool', 'status', pool],
                                   universal_newlines=True)
  prev = percent = percent_match = None
  for line in output.split('\n'):
    if '%' in line:
      percent_match = percent_re.search(line)
      break
    prev = line
  if percent_match is None:
    return None

  percent = float(percent_match.group(1))

  return prev.strip(), percent

def init_ui(pool):
  # bit of a hack but it allows us to reload the module without a segfault
  global app, main_window, details_label, progress_bar
  try:
    app
  except NameError:
    app = QApplication(sys.argv)
  else:
    main_window.destroy()
  main_window = QWidget()
  main_window.resize(250, 150)
  main_window.move(300, 300)
  main_window.setWindowTitle('Resilver progress of {}'.format(pool))
  hbox = QHBoxLayout()
  # hbox.addStretch(1)
  vbox = QVBoxLayout()
  # vbox.addStretch(1)
  hbox.addLayout(vbox)
  main_window.setLayout(hbox)
  details_label = QLabel('loading…')
  details_label.setAlignment(Qt.AlignCenter)
  vbox.addWidget(details_label)
  progress_bar = QProgressBar()
  progress_bar.setAlignment(Qt.AlignCenter)
  vbox.addWidget(progress_bar)

def update_status(pool):
  details, percent = get_status(pool)
  details_label.setText(details)
  progress_bar.setValue(percent)
  main_window.setWindowTitle('{}% — Resilver progress of {}'.format(percent, pool))

def start_timer(pool, interval=300000):
  global timer
  timer = QTimer()
  timer.setInterval(interval)
  def handler():
    update_status(pool)
  timer.timeout.connect(handler)
  timer.start()

if __name__ == '__main__':
  pool = sys.argv[1]
  init_ui(pool)
  main_window.show()
  update_status(pool)
  start_timer(pool)
  sys.exit(app.exec_())