munin diskmon plugin ported to python

linux_diskstats.py

#!/usr/bin/env python3
# ported from https://github.com/terrorobe/munin-plugins/blob/master/alumni/linux_diskstats
# GNP GPLv2

import glob
import re as regex

class diskmon(object):
	"""docstring for diskmon"""

	poll_interval = 300

	def __init__(
		self,
		graph_width=400
	):
		super(diskmon, self).__init__()

		self.graph_width = graph_width

	def parse_diskstats(self):

		stats = False \
			or self.read_sysfs() \
			or self.read_procfs()

		diskstats = None

		for entry in stats:
			devstat = dict(zip([
				'major',
				'minor',
				'devname',
				'rd_ios',
				'rd_merges',
				'rd_sectors',
				'rd_ticks',
				'wr_ios',
				'wr_merges',
				'wr_sectors',
				'wr_ticks',
				'ios_in_prog',
				'tot_ticks',
				'rq_ticks',
			], entry))

			device = devstat['devname']

			pretty_device = None

			if re.match('/^dm-\d+$/', device):
				pretty_device = self.translate_devicemapper_name(device)

			devstat['pretty_device_name'] = pretty_device or device
			# Short device name only containing the stuff after the last '/'
			# for graph labels et al.
			devstat['short_pretty_device_name'] = devstat['pretty_device_name'].split('/')[-1]



	def translate_devicemapper_name(self, device):
		want_minor = re.search('/^dm-(\d+)$/')
		if None is want_minor:
			raise LookupError('Failed to extract devicemapper id')

		dm_major = self.find_devicemapper_major()
		if None is dm_major:
			raise LookupError('Failed to get device-mapper major number')

		for entry in next(os.walk('/dev/mapper/'))[2]:
			entry = os.path.join('/dev/mapper/', entry)
			rdev = int(os.stat(entry).st_dev)
			major, minor = (rdev // 256, rdev % 256)

			if magor == dm_major and minor == want_minor:
				return self.translate_lvm_name(entry)
			return entry

		# Return original string if the device can't be found.
		return $device;


	def read_sysfs(self):
		lines = []

		devices = next(os.walk('/sys/block'))[1]

		for cur_device in devices:
			stats_file = "/sys/block/%s/stat" % tuple(cur_device)

			with open(stats_file) as statfh:
				# Trimming whitespace
				line = statfh.readline().strip()

			elems = re.split('\s+', line)

			if len(elems) is not 11:
				raise LookupError("'%s' doesn't contain exactly 11 values. Aborting" % tuple(stats_file))

			lines.append(elems)

		return lines

	def read_procfs(self):
		lines = []

		with open('/proc/diskstats') as statfh:
			for line in statfh.readlines():
				line = line.strip()

				# Strip trailing newline and leading whitespace
				elems = re.split('\s+', line)

				# We explicitly don't support old-style diskstats
				# There are situations where only _some_ lines (e.g.
				# partitions on older 2.6 kernels) have fewer stats
				# numbers, therefore we'll skip them silently
				if len(elems) != 14:
					continue

				lines.append(elems)

		return lines

	def find_devicemapper_major(self):
		with open('/proc/devices') as devicefh:

			dm_major = None

			for line in devicefh.readlines():
				line = line.strip()

				major, name = re.split('/\s+/', line, 2)

				if not name:
					continue

				if name is 'device-mapper':
					dm_major = major
					break

		return dm_major

	def translate_lvm_name(self, entry):

		device_name = os.path.basename(entry)

		# Check for single-dash-occurence to see if this could be a lvm devicemapper device.
		if re.match('/(?<!-)-(?!-)/', device_name):

			# split device name into vg and lv parts
			vg, lv = re.split('/(?<!-)-(?!-)/', device_name, 2)

			if not vg and not lv:
				return None

			# remove extraneous dashes from vg and lv names
			vg = re.sub('/--/', '-')
			lv = re.sub('/--/', '-')

			device_name = '/'.join(vg, lv)

			# Sanity check - does the constructed device name exist?
			# Breaks unless we are root.
			if os.path.exists(os.path.join('/dev', device_name)):
				return device_name