AWS Lambda function that returns Elastic Beanstalk instance ip address(es)

ebIP.py

import boto3
import json
import re

print('Loading function')

def launch_time(item):
  return (item.launch_time)

def lambda_handler(event, context):
    print("Received event: " + json.dumps(event, indent=2))

    env_name = event['env_name']
    server_number = event.get('server_num')
        
    filters = [{'Name':'tag:elasticbeanstalk:environment-name','Values':[env_name]},
               {'Name':'instance-state-name','Values':['running']}]
    ec2 = boto3.resource('ec2', region_name='ap-northeast-1')
    instances = ec2.instances.filter(Filters=filters).all()
    if not len(list(instances)):
        raise Exception("no instances found for: " + env_name)

    instances_by_launch_time = sorted(instances, key=launch_time)
    if server_number:
        public_ip = instances_by_launch_time[int(server_number) - 1].public_ip_address
    else:
        public_ip = "\n".join(map(lambda x:x.public_ip_address, instances_by_launch_time))

    print("env_name: " + env_name + ", server: " + str(server_number))
    print(instances_by_launch_time)
    print(public_ip)
        
    return public_ip