Filter requests to Rails application by IP address

example.log

Started GET "/" for 220.181.108.76 at 2012-06-01 06:28:48 +0000
Processing by PostsController#index as HTML
  Rendered posts/index.html.erb within layouts/application (2.0ms)
Completed 200 OK in 4ms (Views: 3.4ms | ActiveRecord: 0.2ms)

log_filter.sh

#!/bin/bash
# Filter requests to Rails application by IP address
#
# Usage:
#   tail -f log/production.log | log_filter.sh [IP]
#
#   By default tries to obtain current IP address from $SSH_CLIENT or by querying http://ifconfig.me
if [[ $# -eq 0 ]]; then
  if [[ -z $SSH_CLIENT ]]; then
    ip=$(curl -s http://ifconfig.me)
  else
    ip=$(echo $SSH_CLIENT | sed -e "s/ .*//")
  fi
else
  ip=$1
fi

awk -v IP=$ip '$1=="Started" && $5==IP {accept=1; } $1=="Started" && $5!=IP {accept=0; } accept==1 { print; }'