Script to name all ec2 instances after the node name allocated to the elasticsearch running on that instance.

ec2names.py

#!/usr/bin/python

# Script to name all ec2 instances after the node name allocated to the
# elasticsearch running on that instance. This makes it easy to track back
# to the physical system from visualization tools like bigdesk and head.
#
# Run directly on any elasticsearch node or port forward 9200 to a node in the
# cluster. Simple run without arguments:
# ./ec2names.py
#
# For further configuration, see help:
# ./ec2names.py --help
#
# Suggest croning the script to keeps the names in sync over restarts and new
# nodes.
#
# EC2 credentials are taken from the environment variables:
#  AWS_ACCESS_KEY_ID
#  AWS_SECRET_ACCESS_KEY
#  EC2_REGION
#
# Use in conjunction with ec2-ssh for ssh coolness:
# http://github.com/Instagram/ec2-ssh
#
# (c) 2012 Barnaby Gray

import os
import sys
import boto.ec2
import urllib2
import json
import optparse
import string
import re

def main():
    parser = optparse.OptionParser()
    parser.add_option('--es', help='host:port of an elasticsearch node', default='localhost:9200')
    parser.add_option('--template', help='template for name', default='$name')
    parser.add_option('--group', help='limit to security group(s), eg. group1,group2')
    (options, args) = parser.parse_args()
    
    # first ask elasticsearch for node info
    resp = urllib2.urlopen('http://%s/_cluster/nodes' % options.es)
    nodes = json.load(resp)
    t = string.Template(options.template)
    re_addr = re.compile(r'inet\[/(.+):.+\]')
    ip_to_name = {}
    for node in nodes['nodes'].itervalues():
        m = re_addr.match(node['transport_address'])
        if m:
            ip_to_name[m.group(1)] = t.safe_substitute(node)
    
    # now the ec2 magic
    region = os.getenv('EC2_REGION')
    if not region:
        print 'Please set environment variable EC2_REGION.'
        print 'eg: export EC2_REGION=eu-west-1'
        sys.exit(-1)
    ec2 = boto.ec2.connect_to_region(region)
    
    filters = {}
    if options.group:
        filters['group-name'] = options.group.split(',')
    for r in ec2.get_all_instances(filters=filters):
        for inst in r.instances:
            name = ip_to_name.get(inst.private_ip_address)
            if name and inst.tags.get('Name') != name:
                inst.add_tag('Name', name)
                print 'Set Name: %s on instance %s' % (name, inst.id)
    
if __name__ == '__main__':
    main()