You need to use logresolvemerge Perl script which is part of AWStats package. The logresolvemerge allows you to get one unique output log file, sorted on date, built from particular sources:

• Act as a log merger for any other log analyzer.
• It can read several input log files.
• It can read .gz/.bz2 log files.
• It can also makes a fast reverse DNS lookup to replace; all IP addresses into host names in resulting log file.

Step #1: Install awstats

Turn on EPEL repo from the Fedora project and use the yum command install awstats package, enter:
# yum -y install awstats
Please note that the perl based log merger script is installed at /usr/share/awstats/tools/logresolvemerge.pl.

Step #2: Grab Logs From All Other Servers / Node

Our sample setup is as follows:

	+----------+
	| apache1  + 192.168.1.10
	+-----+----+
              |
	+-----+----+
	| apache2  + 192.168.1.11
	+-----+----+
	      |
	+-----+----+
	| apache3  + 192.168.1.12
	+-----+----+
              |
------------+----------+-----------------------------
|           |          |   LAN 
------+     +-------+  +-------------+ 
Nginx |     |mysql1 |  | cachingnode |
lb1   |     |cluster|  | / stats     | 192.168.1.20
------+     +-------+  +-------------+
202.54.1.1              

Where,

• You need to fetch logs from apache1, apache2, and apache3 nodes.
• You will use caching node to build stats.

First, create a directory to store logs. Type the following commands on cachingnode (192.168.1.20)
# D=/var/logs/clusterlogs
# mkdir -p $D
# mkdir -p $D/raw
# mkdir -p $D/raw/apache{1,2,3}
# mkdir -p $D/reports
Use the rsync command to fetch log files from each server:
# rsync -azv user@apache1:/var/logs/httpd/access_logs* $D/raw/apache1
# rsync -azv user@apache2:/var/logs/httpd/access_logs* $D/raw/apache2
# rsync -azv user@apache3:/var/logs/httpd/access_logs* $D/raw/apache3

Step #3: Merge Log Files

Use logresolvemerge.pl as follows to merge all log files, enter:
# /usr/share/awstats/tools/logresolvemerge.pl $D/raw/apache1/access_logs* $D/raw/apache2/access_logs* \
$D/raw/apache3/access_logs* > $D/raw/merged_access_logs

The above will create a new file called $D/raw/merged_access_logs. You need to use this file to create logs. You can delete the rest of all files:
# rm -f $D/raw/apache1/access_logs*
# rm -f $D/raw/apache2/access_logs*
# rm -f $D/raw/apache3/access_logs*

Step #4: How Do I Generate Graphs With Webalizer?

The Webalizer is a fast, free, web-server log files analysis program. See how to install Webalizer. You need to create webalizer configuration file, enter:
# mkdir -p $D/reports/webalizer
# cp /etc/webalizer.conf.sample $D/reports/webalizer/webalizer.conf
Edit config file, enter:
# vi $D/reports/webalizer/webalizer.conf
Update it as follows:

LogFile         /var/logs/clusterlogs/raw/merged_access_logs
OutputDir       /var/www/usage
HistoryName     /var/logs/clusterlogs/raw/webalizer.hist
Incremental     yes
IncrementalName /var/logs/clusterlogs/raw/webalizer.current
HostName        cyberciti.biz

Save and close the file. To generate stats, enter:
# webalizer -c $D/reports/webalizer/webalizer.conf
Your reports will be generated and stored at /var/www/usage directory. You can access /var/www/usage using apache server running on cachingnode (http://cachingnode/usage/).

Step #5: How Do I Generate Graphs With AWStats?

AWStats is a free powerful tool that generates advanced web, streaming, ftp or mail server statistics, graphically. This log analyzer works as a CGI or from command line. See how to install AWStats under Linux. Once installed edit awstats configuration file, enter:
# vi /etc/awstats/awstats.cyberciti.biz.conf
Update config directives as follows:

LogFile="/var/logs/clusterlogs/raw/merged_access_logs"
LogFormat=1
SiteDomain="cyberciti.biz"
DirData="/var/www/usage/awstats"

Save and close the file. Type the following command at a shell prompt to generate stats, enter:
# /usr/share/awstats/wwwroot/cgi-bin/awstats.pl -update -config=cyberciti.biz

Cron Job: Fetch Log Files And Generate Stats

Create a shell script as follows using cron jobs:
# vi /etc/cron.daily/fetchapachelogs.sh
Append the code:

#!/bin/bash
# Author: Vivek Gite <vivek@nixcraft.com>, under GPL v2.0+
# --------------------------------------------------------------------
D="/var/logs/clusterlogs"
# user1@remote1:/path/to/log user2@remote2:/path/to/log
_nodes='user@apache1:/var/logs/httpd/access_logs*  user@apache2:/var/logs/httpd/access_logs*  user@apache3:/var/logs/httpd/access_logs*'
# Set full path with args
_rsync="/usr/bin/rsync -az "
_mkdir="/bin/mkdir"
_rm="/bin/rm"
_webalizer="/usr/bin/awstats"
_awstats="/usr/share/awstats/wwwroot/cgi-bin/awstats.pl"
_merge="/usr/share/awstats/tools/logresolvemerge.pl"
# log files and dirs
_mergedlog="$D/raw/merged_access_logs"
_path=""
 
# Build path and fetch log files
[ ! -d "$D/raw" ] && $_mkdir -p "$D/raw"
for f in $_nodes
do
	IFS=':'
	set -- $f
	n="$D/raw/${1##*@}"
	[ ! -d "$n" ] && $_mkdir -p "$n"
        # grab the log file
	$_rsync "$f" "$n"
	_path="$_path $n/* "
done
 
# Merge it 
$_merge "$_path" >"$_mergedlog"
 
# Generate webalizer stats
[ -f $D/reports/webalizer/webalizer.conf ] && $_webalizer -c $D/reports/webalizer/webalizer.conf &>/dev/null
 
# Generate Awstats too
# [ -x $_awstats ] && $_awstats -update -config=cyberciti.biz
 
# Add your other stats commands here
## /path/to/my_stats_app  -f "$D/reports/webalizer/webalizer.conf"
# Add your other stats commands here
 
# Clean up
$_rm -f "$_mergedlog"
$_rm -f "$_path"