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1#! /usr/bin/env python
2
3import argparse
4import os
5import sys
6
7import boto.ec2
8
9
10def parse_args():
11    parser = argparse.ArgumentParser(
12        description='Display EC2 hosts in ssh-config or hosts file format',
13        formatter_class=argparse.ArgumentDefaultsHelpFormatter)
14
15    parser.add_argument('-k', '--aws-key', type=str,
16        default=os.environ.get("AWS_ACCESS_KEY_ID"),
17        help='Amazon EC2 Key, defaults to ENV[AWS_ACCESS_KEY_ID]')
18    parser.add_argument('-s', '--aws-secret', type=str,
19        default=os.environ.get("AWS_SECRET_ACCESS_KEY"),
20        help='Amazon EC2 Secret, defaults to ENV[AWS_SECRET_ACCESS_KEY]')
21    parser.add_argument('-r', '--region', type=str,
22        default=os.environ.get("AWS_EC2_REGION"),
23        help='Amazon EC2 Region, defaults to us-east-1 or ENV[AWS_EC2_REGION]')
24
25    parser.add_argument('-t', '--tag', type=str,
26        default='Name', dest='name_tag',
27        help="Amazon EC2 Tag for instance name, defaults to 'Name'")
28
29    parser.add_argument('--prefix', type=str, default='',
30        help='prefix to the instance name')
31    parser.add_argument('--suffix', type=str, default='',
32        help='suffix to the instance name')
33    parser.add_argument('--domain', type=str, default='',
34        help='domain to the instance name')
35
36    parser.add_argument('--format', choices=['ssh', 'hosts'], default='ssh',
37        help='output format. ssh-config or hosts file style. ')
38    parser.add_argument('--filter', type=str, action='append', default=[],
39        help=('Amazon EC2 API filter to limit the result returned. '
40              '(Example: --filter instance-state-name=running)'))
41    parser.add_argument('--use-elastic-ip', action='store_true',
42        help='use elastic IP instead of private IP')
43
44    return parser.parse_args()
45
46
47def main(opts):
48    aws_key = opts['aws_key']
49    aws_secret = opts['aws_secret']
50    region = opts['region']
51    name_tag = opts['name_tag']
52    prefix = opts['prefix']
53    suffix = opts['suffix']
54    domain = opts['domain']
55    format = opts['format']
56    filter = opts['filter']
57    use_elastic_ip = opts['use_elastic_ip']
58
59    filters = dict([f.split('=', 1) for f in filter])
60    if domain and not domain.startswith('.'):
61        domain = '.' + domain
62
63    ip_addr_attr = 'ip_address' if use_elastic_ip else 'private_ip_address'
64
65    # validation
66    if not aws_key or not aws_secret:
67        if not aws_key:
68            print >> sys.stderr,\
69            "AWS_ACCESS_KEY_ID not set in environment and not",\
70            "specified by -k AWS_KEY or --aws-key AWS_KEY"
71        if not aws_secret:
72            print >> sys.stderr,\
73            "AWS_SECRET_ACCESS_KEY not set in envoronment and not",\
74            "specified by -s AWS_SECRET or --aws-secret AWS_SECRET"
75        sys.exit(2)
76
77    region = region and boto.ec2.get_region(region,
78        aws_access_key_id=aws_key,
79        aws_secret_access_key=aws_secret)
80
81    conn = boto.ec2.connection.EC2Connection(aws_key, aws_secret,
82        region=region)
83
84    # list of (instance_name, ip_address)
85    instances = get_ec2_instances(conn, name_tag, ip_addr_attr, filters)
86
87    # sort by name
88    instances = sorted(instances)
89
90    # print out
91    print_fn = print_ssh_config if format == 'ssh' else print_hosts
92    print_fn(instances, prefix, suffix, domain)
93
94
95def get_ec2_instances(conn, name_tag, ip_addr_attr, filters):
96    instances = []  # (instance_name, ip_address)
97    reservations = conn.get_all_instances(filters=filters)
98    for reservation in reservations:
99        for instance in reservation.instances:
100            instance_name = instance.tags.get(name_tag)
101            ip_address = getattr(instance, ip_addr_attr)
102            if instance_name and ip_address:
103                pair = (instance_name, ip_address)
104                instances.append(pair)
105    return instances
106
107
108def print_ssh_config(instances, prefix, suffix, domain):
109    """ Print out as ssh-config file format """
110    for instance_name, ip_address in instances:
111        instance_name = prefix + instance_name + suffix + domain
112        # double quote if name contains space
113        instance_name = '"{0}"'.format(
114            instance_name) if ' ' in instance_name else instance_name
115        print "Host %s" % instance_name
116        print "Hostname %s" % ip_address
117        print ""
118
119
120def print_hosts(instances, prefix, suffix, domain):
121    """ Print out as hosts file format """
122    for instance_name, ip_address in instances:
123        if ' ' in instance_name:
124            continue  # skip if name contains space.
125        instance_name = prefix + instance_name + suffix + domain
126        print "%s\t%s" % (ip_address, instance_name)
127
128
129if __name__ == '__main__':
130    args = vars(parse_args())
131    main(args)