Print EC2 instances by tag value

getinstances.py

#!/usr/bin/python

# Used on bastion host (jumpbox)
# e.g.: for feedserver in $(/usr/bin/getinstances feed-server); do echo $feedserver; ssh $feedserver; done;
# @todo: make VPC detection automatic

import sys
import json
import subprocess

from pprint import pprint

cluster = sys.argv[1]

cmd = 'aws ec2 describe-instances --filters "Name=tag-value,Values=' + cluster + '" "Name=instance-state-code,Values=16" "Name=vpc-id,Values=vpc-e5dd9d8d"'
push = subprocess.Popen(cmd, shell=True, stdout = subprocess.PIPE)
output, err = push.communicate()

parsed = json.loads(output)

for instances in parsed['Reservations']:
	for instance in instances['Instances']:
		print instance['PrivateIpAddress']