#!/usr/bin/env python
#
# Plugin created for capturing RX and TX statistics from Linux OS
# interfaces.
# Useful to analyze package tendencies, such as total transfered, 
# dropped, framed and overrun packets. This plugin follows a very
# simple approach and outputs a nagios formatted metric syntax for
# chart creation.
#
# IMPORTANT: This script relies on `ifconfig` command, so soon it 
# will be outdated but I hope to rewrite using a better replacement 
# like ethtool or ip.
# 
# To better explain the output:
#
# - RX: Received packets
# - TX: Transfered packets
# - errors: Packets which could not be transfered/received due
#   errors
# - dropped: Normally indicates configuration/communication
#   errors (eg: One side operating in half-duplex and the other
#   in full-duplex)
# - overruns: The interface has two buffers, one for transmit
#   and the other one for receive and when one of these buffers
#   reachs its limit the surplus packets are discarted as 
#   'overrruns'
# - frame: Malformed frames
# - carrier: Physical link error. Very common in HUBS, should not
#   never occur with switch environments.
#
# Usage: check_rx_tx.py <OS Interface>
#
# Author: Marcelo Varge
#        (marcelo.varge@gmail.com)
#
#
import sys
from commands import getoutput

# Usage/Help:
def usage():
    print "Usage: %s <OS Interface>" % (sys.argv[0])
    sys.exit(-1)

# Check received parameters:
if (len(sys.argv) < 2) or (sys.argv[1].lower() == "-h"):
    usage()

# Variable/Constants definitions
interface = sys.argv[1]

capture   = ('RX packets',
             'TX packets',
            )

format    = []
final     = []

# Capture output:
out = getoutput("ifconfig %s" % interface)

if "Device not found" in out:
    print out
    sys.exit(-1)

for line in out.splitlines():
    for opt in capture:
        if opt in line:
            format.append(line.split())

# Format final output:
for line in format:
    name = line.pop(0)
    for opt in line:
        temp = opt.split(':')
        final.append(name + '_' + temp[0] + '=' + temp[1])

# Print output for nagios metrics
print "OK | " + ';'.join(final)
sys.exit(0)