#!/bin/bash
#
# Title: script.monitor.sh
# Description: Script that monitors the teh3l3m3nts minecraft server
# Author: Joseph Gullo (surfrock66) (surfrock66@surfrock66.com)
#
# This is a comprehensive monitoring script to use for the teh3l3m3nts
# minecraft server. It can be used in 3 configurations for 3 types
# of monitoring:
#
# 0 - Monitoring the server process from inside the same machine.
# This configuration first checks that a java process is running;
# this would indicate that the server is running. If there is no
# java process, then the server is offline. If java is running,
# then attempt to send a command to the server initiating a "ping"
# which will print a log entry. Then, generate the current date and
# time. Parse out the most recent line of the minecraft log file,
# and parse the date and time out of that. Now we're checking to
# see if the last log entry is basically the same time as the current
# check, indicating that the server is currently accepting commands.
# Through my testing, they are usually off by about 9 seconds. First
# check that the date is the same (this thing is gonna be cron'd to
# run every 5 minutes...if it REALLY catches the server at the precise
# monent the date rolls over...fine whatever. Next, check that the
# hours are the same, again, if the 9 second delay JUST HAPPENS to
# catch it at the rollover, whatever, possible unnecessary log file.
# Finally, check that the minutes are the same...OR WITHIN 1 OF EACH
# OTHER! I believe this will alleviate most of the erroneous error alerts.
# 1 - Monitoring the server from inside the same network; the impetus
# is that if the machine is down, it won't be able to alert us to its
# status. This basically pings the server machine to see if it's running.
# 2 - Monitoring the entire network from the outside; what if the internet
# goes out at the house the server is being run at? Check to see if the
# network is reachable...mostly using a DynDNS resolver since we're all
# on residential internet.
#
# As the script proceeds, it builds a message that will be the body of
# a message should one be triggered. All errors are added to provide
# the best diagnostic steps.
#
# Potential Concerns:
# 1) Let's say the server reboots and gets stuck in the
# BIOS...will it survive the ping (passing check 1) but not send an error
# message from inside the server, meaning cron and the server are down?
# We wouldn't be alerted in this case. Investigate triggers that the
# OS is running to a point that we can be satisfied cron (and the
# internal monitoring script) is running.
# 2) What if the power goes out, but within a 5 minute cron window it
# comes back on, making the router come alive but not any of the servers
# for some reason. Ideally with the modem reset we'd get a new IP so the
# DynDNS wouldn't resolve, but it's POSSIBLE that if the IP doesn't change,
# the ping from outside the network hits the router even though the
# servers are all down. Possibly investigate pinging a specific service,
# in this setup, on surfrock66's HDA (such as subsonic)
#

#Variable that chooses whic set of script commands to run, based on location
# Must be one of the following:
# 0 = Monitoring from inside the same machine
# 1 = Monitoring from different machine inside same network
# 2 = Monitoring from different machine outside the network
MONITORLOC="0"

# This is the name of the screen holding the server process
NAME="Bukkit"
# This is the description of the server, used in sending in-game notices
DESC="teh3l3m3nts Minecraft Server"

# E-mail subject for any error e-mails going out
SUBJECT="TEH3L3M3NTS MINECRAFT SERVER MONITORING ALERT!"

# Team e-mail addresses to send alerts to
TOJOE="surfrock66@surfrock66.com"
TOMIKE="landers.mike@gmail.com"
TONATE="nathan.lowell@arvixe.com"
TOSERVER="minecraftpisspants@gmail.com"

# Temporary file to store alert message as it's constructed
MESSAGE="/tmp/message.txt"

# Address to ping the server's network from outside the network
HOSTMC="surfrock66.yourhda.com"

# Address to ping the server from inside the network
SERVERIP="192.168.1.50"

# Processname to check to see if the server is running
SERVERPROCESS="java"

# Location of the server's logfile
LOGFILE="/var/bukkit/server.log"

# Errorflag, defaults to 0 for No Error, can be set to 1 for Error
ERRORFLAG=0

# Initiate the message file that becomes the content of an alert e-mail
echo "MONITORING ALERT FOR TEH3L3M3NTS MINECRAFT SERVER!" > $MESSAGE

if [ $MONITORLOC == "2" ]; then

    #####
    #
    # Code for testing server access from another box outside the netork
    #

    # Ping the home network from outside of the network
    ping -c 1 $HOSTMC &> /dev/null
    
    # If the ping produces no response, then initiate an error message
    if [ $? -ne 0 ]; then
        echo "Ping to teh3l3m3nts server failed, network is down!" >> $MESSAGE
        # Change the flag which triggers the e-mail alert
        ERRORFLAG=1
    else
        # If the ping succeeds, add a message to the error message
        # indicating successful steps
        echo "Ping to teh3l3m3nts server succeeded, network is up!" >> $MESSAGE
    fi
    
    #
    # End of outside-network access test.
    #
    #####
    
elif [ $MONITORLOC == "1" ]; then

    #####
    #
    # Code for testing server access from another box on the same netork
    #
    
    # Ping the server machine from inside the network
    ping -c 1 $SERVERIP &> /dev/null
    
    # If the ping produces no response, then initiate an error message
    if [ $? -ne 0 ]; then
        echo "Ping to teh3l3m3nts server failed, server is down!" >> $MESSAGE
        # Change the flag which triggers the e-mail alert
        ERRORFLAG=1
    else
        # If the ping succeeds, add a message to the error message
        # indicating successful steps
        echo "Ping to teh3l3m3nts server succeeded, server is up!" >> $MESSAGE
    fi
    
    #
    # End of same-network access test.
    #
    #####
    
elif [ $MONITORLOC == "0" ]; then

    #####
    #
    # Code for testing if the server is up from the same machine
    #
    
    # Poll running services for the server's process, stores the PID
    SERVERID=$(pgrep "$SERVERPROCESS")
    # Check that the server's process is running
    if [ $SERVERID ]; then
        # Add an indicator that the process is running to the message
        echo "teh3l3m3nts minecraft server process is running!" >> $MESSAGE
        # Check that the server's logfile exists
        if [ -f $LOGFILE ]; then
            # Send a ping command to the server to generate a new timecode line
            screen -dr "$NAME" -p 0 -X stuff "$(printf "ping\r")"
            # Grab the last line of the log file...likely the above ping
            LOGEND=$(tail -1 "$LOGFILE")
            # Add the date and time to a variable in the same format as
            # the minecraft log timestamp
            DATESTR=$(date +"%Y-%m-%d %H:%M:%S")
            # Parse out just the date and time string
            TIMECODE=${LOGEND:0:19}
            # Set the date to a variable from the logfile line
            TIMECODE=${LOGEND:0:10}
            # Extract the date to a variable from the current timecode
            DATECODE=${DATESTR:0:10}
            # Check to make sure the last log entry is on the same day as
            # the current timecode
            if [ "$TIMECODE" == "$DATECODE" ]; then
                # Indicate at least the datecodes match in the e-mail message
                echo "Log being written to, datecodes match!" >> $MESSAGE
                # Parse out the hour from the log entry
                TIMECODE=${LOGEND:11:2}
                # Parse out the hour from the current timecode
                DATECODE=${DATESTR:11:2}
                # Check to make sure the last log entry is the same hour as
                # the current timecode
                if [ "$TIMECODE" == "$DATECODE" ]; then
                    # Indicate at least the hours match in the e-mail message
                    echo "Log being written to, timecode hours match!" >> $MESSAGE
                    # Parse out the minute from the log entry
                    TIMECODE=${LOGEND:14:2}
                    # Parse out the minute from the current timecode
                    DATECODE=${DATESTR:14:2}
                    # Convert the log minute to a number from a string
                    LOGMIN=$(( 10#$TIMECODE ))
                    # Convert the current minute to a number from a string
                    DATEMIN=$(( 10#$DATECODE ))
                    # Add a second variable for 1 more than the log minute
                    LOGMIN1=$(($LOGMIN+1))
                    # Check to see if the log and current minutes are within
                    # 1 of each other, which is close-enough
                    if [ "$LOGMIN" == "$DATEMIN" -o "$LOGMIN1" == "$DATEMIN" ]; then
                        # Indicate that the minutes basically match in the message
                        echo "Log being written to, timecode minutes match!" >> $MESSAGE
                    else
                        # If the last log line is too different of a minute
                        # than the current timecode, trigger an error
                        echo "Log not being written to, timecode minutes mismatch, server is OFFLINE!" >> $MESSAGE
                        # Change the flag which triggers the e-mail alert
                        ERRORFLAG=1
                    fi
                else
                    # If the last log line is a differnt hour than now,
                    # trigger an error
                    echo "Log not being written to, timecode hours mismatch, server is OFFLINE!" >> $MESSAGE
                    # Change the flag which triggers the e-mail alert
                    ERRORFLAG=1
                fi
            else
                # If the last log line is a different date than now, trigger
                # an error.
                echo "Log not being written to, datecode mismatch, server is OFFLINE!" >> $MESSAGE
                # Change the flag which triggers the e-mail alert
                ERRORFLAG=1
            fi
            
        else
            # If there is no log file, trigger an error message
            echo "There appears to be no logfile!" >> $MESSAGE
            # Change the flag which triggers the e-mail alert
            ERRORFLAG=1
        fi
    else
        # If the server's process isn't running, the initiate an error message
        echo "teh3l3m3nts minecraft server process is NOT running!" >> $MESSAGE
        # Change the flag which triggers the e-mail alert
        ERRORFLAG=1
    fi
    
    #
    # End of same-machine accss test
    #
    #####
    
fi

# Check if the error is indicated, then initiate sending messages to
# all owners.
if [ $ERRORFLAG == "1" ]; then
    echo "ERROR DETECTED, SENDING MAIL!"
    mail -s "$SUBJECT" "$TOJOE" < $MESSAGE
    mail -s "$SUBJECT" "$TOMIKE" < $MESSAGE
    mail -s "$SUBJECT" "$TONATE" < $MESSAGE
    mail -s "$SUBJECT" " $TOSERVER" < $MESSAGE
fi