#!/usr/bin/env python3

import argparse
import boto.ec2
import json
import re
import sys

parser = argparse.ArgumentParser(description = 'Find out information about EC2 instances')
parser.add_argument('--region', default = 'us-west-2', help = 'The AWS region to search')
parser.add_argument('--limit', type = int, default = 1, help = 'How many results to report, 0 will return all')
parser.add_argument('--output', default = 'private_ip_address', help = 'The output to fetch for each instance; json will output a json object will all of the outputs')
parser.add_argument('filters', nargs = argparse.REMAINDER, help = 'Regular expressions to apply to each tag')
args = parser.parse_args()

ec2 = boto.ec2.connect_to_region('us-west-2')

if not args.filters:
    raise Exception('You must specify at least one instance')

def include_instance(instance):
    if instance.state != 'running':
        return

    if not args.filters:
        return instance

    for filter in args.filters:
        for tag_key in instance.tags:
            tag_value = instance.tags[tag_key]
            tag = '{}={}'.format(tag_key, tag_value).lower()

            if re.search(filter, tag_value):
                return instance


def filter():
    for reservation in ec2.get_all_instances():
        for instance in reservation.instances:
            if include_instance(instance):
                yield instance

for i, instance in enumerate(filter(), 1):
    if args.output == 'json':
        print(json.dumps(instance.__dict__, default = str))
    else:
        print(getattr(instance, args.output))

    if args.limit and i >= args.limit:
        break

$ ssh `ec2 prod-server`

ec2 --limit 0 --output json | jq '.instance_type' | sort | uniq -c | sort -nr

  27 "t2.micro"
   5 "m3.medium"
   1 "c4.xlarge"