List all EC2 instances in a region and their public IPs (handy for populating hosts file)

ec2hosts.py

from boto.ec2 import *

import argparse
parser = argparse.ArgumentParser()
parser.add_argument("access_key", help = "AWS Access Key")
parser.add_argument("secret_key", help = "AWS Secret Key")
parser.add_argument("--region", help = "AWS Region", default = "us-east-1")
parser.add_argument("--all", help = "show not just running instances", action = "store_true")

args = parser.parse_args()

conn = connect_to_region(args.region, aws_access_key_id = args.access_key, aws_secret_access_key = args.secret_key)

instances = conn.get_only_instances()

filters = { }

if not args.all:
	filters = {
	 'instance-state-name' : 'running'
	}

instances = conn.get_only_instances(filters = filters)

for instance in instances:
	print instance.ip_address + " " + instance.tags['Name']