Traffic accounting through proc

Traffic Accounting through /proc/net/dev

Introduction

Traffic accounting in OpenVZ can be done through data collection against /proc/net/dev in the individual containers on a HN.

Prerequisites

• OpenVZ
• RRDTool
• GNU AWK

Script

First create a directory to store your RRD files:

# mkdir /var/lib/rrd/

Then install this script:

#!/bin/sh
# Script Name:  vz_direct_traffic_log
# Author:       "Brian Harrington, Alticon Inc" <bharrington@alticon.net>
# Website:      htty://www.alticon.net

# Time to do the data collection.
for veid in `/usr/sbin/vzlist -o veid -H | sed 's/ //g'`; do

               RRDFILE="/var/lib/rrd/$veid.rrd"
 
               if ! test -e $RRDFILE; then
                       echo $RRDFILE does not exist, creating.
                       # Place your preferred RRD Creation command here
                       # TODO: please provide an example
               fi
 
               # Parse out the inbound/outbound traffic and assign them to the corresponding variables
               eval `/usr/sbin/vzctl exec $veid "grep venet0 /proc/net/dev"  |  \
                       awk -F: '{print $2}' | awk '{printf"CTIN=%-15d\nCTOUT=%-15d\n", $1, $9}'`
 
               # Send the data to the corresponding RRD time with (N)now as the update time
               /usr/bin/rrdtool update $RRDFILE N:$CTIN:$CTOUT
done

Setup

Add this to cron to run every 5 minutes:

# echo "*/5 * * * * root /path/to/script/vz_direct_traffic_log " >> \
  /etc/crontab && /etc/init.d/crontab restart

Better use the cron system of OpenVZ

# echo "*/5 * * * * root /path/to/script/vz_direct_traffic_log " >> \
  /etc/vz/cron/vz-traffic.sh && /etc/init.d/vz update-cron

To check the output of this later run:

# rrdtool fetch /var/lib/rrd/<veid>.rrd AVERAGE -s -3600

See also

• Traffic accounting with iptables
• Monitoring bandwidth of containers