display ec2-name and ip-address as ssh-config or hosts file

Inspired by this instagram engineering blog, I wrote a python script to printout ec2 hostname and ip-address as ssh-config or hosts file format.

In our environment, unfortunately we don't have dns for ec2 hosts, for now. 

I use /etc/hosts. Some people use ssh-config file.

This script may help others who are in similar environment where using ssh-config or hosts file to manage ec2-host mapping.

Usage

	# display entries as ssh-config file format
	./ec2-printconfig -k <aws_key> -s <aws_secret> -r us-west-2
	# display entries as hosts file format
	./ec2-printconfig --format hosts
	# add prefix "my-" to instance name. (ex: my-foo, my-bar, ...)
	./ec2-printconfig --prefix my-
	# add domain "mydomain.com" to instance name. (ex: foo.mydomain.com, bar.mydomain.com, ...)
	./ec2-printconfig --domain mydomain.com
	# use elastic IP instead of private IP
	./ec2-printconfig --use-elastic-ip
	# filter instances. (ex: only running and monitored instances. )
	./ec2-printconfig --filter monitoring-state=enabled --filter instance-state-name=running
	# specify tag for ec2 instance name. (ex: assume there is "alias" tag)
	./ec2-printconfig -t alias

view raw usage hosted with ❤ by GitHub

ec2-printconfig script

	#! /usr/bin/env python
	import argparse
	import os
	import sys
	import boto.ec2
	def parse_args():
	parser = argparse.ArgumentParser(
	description='Display EC2 hosts in ssh-config or hosts file format',
	formatter_class=argparse.ArgumentDefaultsHelpFormatter)
	parser.add_argument('-k', '--aws-key', type=str,
	default=os.environ.get("AWS_ACCESS_KEY_ID"),
	help='Amazon EC2 Key, defaults to ENV[AWS_ACCESS_KEY_ID]')
	parser.add_argument('-s', '--aws-secret', type=str,
	default=os.environ.get("AWS_SECRET_ACCESS_KEY"),
	help='Amazon EC2 Secret, defaults to ENV[AWS_SECRET_ACCESS_KEY]')
	parser.add_argument('-r', '--region', type=str,
	default=os.environ.get("AWS_EC2_REGION"),
	help='Amazon EC2 Region, defaults to us-east-1 or ENV[AWS_EC2_REGION]')
	parser.add_argument('-t', '--tag', type=str,
	default='Name', dest='name_tag',
	help="Amazon EC2 Tag for instance name, defaults to 'Name'")
	parser.add_argument('--prefix', type=str, default='',
	help='prefix to the instance name')
	parser.add_argument('--suffix', type=str, default='',
	help='suffix to the instance name')
	parser.add_argument('--domain', type=str, default='',
	help='domain to the instance name')
	parser.add_argument('--format', choices=['ssh', 'hosts'], default='ssh',
	help='output format. ssh-config or hosts file style. ')
	parser.add_argument('--filter', type=str, action='append', default=[],
	help=('Amazon EC2 API filter to limit the result returned. '
	'(Example: --filter instance-state-name=running)'))
	parser.add_argument('--use-elastic-ip', action='store_true',
	help='use elastic IP instead of private IP')
	return parser.parse_args()
	def main(opts):
	aws_key = opts['aws_key']
	aws_secret = opts['aws_secret']
	region = opts['region']
	name_tag = opts['name_tag']
	prefix = opts['prefix']
	suffix = opts['suffix']
	domain = opts['domain']
	format = opts['format']
	filter = opts['filter']
	use_elastic_ip = opts['use_elastic_ip']
	filters = dict([f.split('=', 1) for f in filter])
	if domain and not domain.startswith('.'):
	domain = '.' + domain
	ip_addr_attr = 'ip_address' if use_elastic_ip else 'private_ip_address'
	# validation
	if not aws_key or not aws_secret:
	if not aws_key:
	print >> sys.stderr,\
	"AWS_ACCESS_KEY_ID not set in environment and not",\
	"specified by -k AWS_KEY or --aws-key AWS_KEY"
	if not aws_secret:
	print >> sys.stderr,\
	"AWS_SECRET_ACCESS_KEY not set in envoronment and not",\
	"specified by -s AWS_SECRET or --aws-secret AWS_SECRET"
	sys.exit(2)
	region = region and boto.ec2.get_region(region,
	aws_access_key_id=aws_key,
	aws_secret_access_key=aws_secret)
	conn = boto.ec2.connection.EC2Connection(aws_key, aws_secret,
	region=region)
	# list of (instance_name, ip_address)
	instances = get_ec2_instances(conn, name_tag, ip_addr_attr, filters)
	# sort by name
	instances = sorted(instances)
	# print out
	print_fn = print_ssh_config if format == 'ssh' else print_hosts
	print_fn(instances, prefix, suffix, domain)
	def get_ec2_instances(conn, name_tag, ip_addr_attr, filters):
	instances = [] # (instance_name, ip_address)
	reservations = conn.get_all_instances(filters=filters)
	for reservation in reservations:
	for instance in reservation.instances:
	instance_name = instance.tags.get(name_tag)
	ip_address = getattr(instance, ip_addr_attr)
	if instance_name and ip_address:
	pair = (instance_name, ip_address)
	instances.append(pair)
	return instances
	def print_ssh_config(instances, prefix, suffix, domain):
	""" Print out as ssh-config file format """
	for instance_name, ip_address in instances:
	instance_name = prefix + instance_name + suffix + domain
	# double quote if name contains space
	instance_name = '"{0}"'.format(
	instance_name) if ' ' in instance_name else instance_name
	print "Host %s" % instance_name
	print "Hostname %s" % ip_address
	print ""
	def print_hosts(instances, prefix, suffix, domain):
	""" Print out as hosts file format """
	for instance_name, ip_address in instances:
	if ' ' in instance_name:
	continue # skip if name contains space.
	instance_name = prefix + instance_name + suffix + domain
	print "%s\t%s" % (ip_address, instance_name)
	if __name__ == '__main__':
	args = vars(parse_args())
	main(args)

view raw ec2-printconfig.py hosted with ❤ by GitHub