check_grubentry

#!/usr/bin/env python3
#-------------------------------------------------------------------------------

import argparse
import sys
import os
import subprocess
import platform
import re

#-------------------------------------------------------------------------------

_candebug = False
def candebug():
    global _candebug
    return _candebug
def setcandebug(value):
    global _candebug
    _candebug = value

def infomsg(msg):
    if candebug() == True:
        print(msg, flush=True)

def exitnagios(status,message):
    if status=="OK":
        exitcode = 0
    elif status=="WARNING":
        exitcode = 1
    elif status=="CRITICAL":
        exitcode = 2
    elif status=="UNKNOWN":
        exitcode = 3
    else:
        exitcode = 4
    print(status+": "+message, flush=True)
    sys.exit(exitcode)

#-------------------------------------------------------------------------------

def dogrubentrycall(expectedpos):
    try:
        lines = []
        handle = open("/boot/grub/grub.cfg", "r")
        try:
            lines = handle.read().strip().splitlines()
        finally:
            handle.close()
        allcandidates = []
        for line in lines:
            line = line.strip()
            if line.startswith("menuentry "):

                singlequotes = re.findall("'([^']*)'", line)
                if len(singlequotes)>0:
                    allcandidates.append(singlequotes[0])
                doublequotes = re.findall('"([^"]*)"', line)
                if doublequotes!=None:
                    if len(doublequotes)>0:
                        allcandidates.append(doublequotes[0])
        validcandidates = []
        for item in allcandidates:
            if item.startswith("Debian GNU/Linux"):
                validcandidates.append(item)
        infomsg(validcandidates)
        expectedstring = validcandidates[expectedpos]
        infomsg("expected -> "+expectedstring)

        cmdline = ["/usr/bin/uname","--kernel-release"]
        completedproc = subprocess.run(cmdline,capture_output=True)
        output = completedproc.stdout.decode("utf-8").strip()
        errors = completedproc.stderr.decode("utf-8").strip()
        exitcode = completedproc.returncode
        version = ""
        if exitcode == 0:
            version = output.strip()
        runningending = ", with Linux "+version
        infomsg("running -> "+runningending)

        if expectedstring.endswith(runningending):
            exitnagios("OK","grub entry '"+str(expectedpos)+" - "+expectedstring+"' matches the running version '"+version+"'")
        else:
            exitnagios("WARNING","running grub entry with version '"+version+"' but it was expected '"+expectedstring+"'")
    except Exception as e:
        exitnagios("CRITICAL","internal issue - "+str(e))

#-------------------------------------------------------------------------------

def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("-e", "--expected",                                dest="expected",         default="0",                                  help="expected")
    parser.add_argument("-®", "--debug",             action="store_true",  dest="debug",            default=False,                                help="be more verbose")
    args = parser.parse_args()

    setcandebug(args.debug)

    expected = int(args.expected)
    dogrubentrycall(expected)

if __name__ == "__main__":
    main()

#-------------------------------------------------------------------------------