Create the ssh_config from for all the aws machines

aws_ssh_config.py

#!/usr/bin/python

"""AWS EC2 SSH config Generator."""

import boto3
import os
import sys

# The location and name of our generated config file
path_to_config = '/.ssh/aws_demo'

# The SSH key we use to connet to those instances
path_to_ssh_key = "~/.ssh/xxx.pem"

def main():
    """Main."""
    try:
        """
        Using the security credentialsa and the location we set
        when we run `$ awscli configure` we connect to AWS
        and get the list of instances on the specific location
        """
        aws_client = boto3.client('ec2')
        paginator = aws_client.get_paginator('describe_instances')
        response_iterator = paginator.paginate(
            DryRun=False,
            PaginationConfig={
                'MaxItems': 100,
                'PageSize': 10
            }
        )

        """
        Open the config file we specified to be written
        """
        ssh_config_file = open(os.path.expanduser(
            '~') + path_to_config, 'w')

        ssh_config_file.write("##########################\n")
        ssh_config_file.write("##### AWS SSH CONFIG #####\n")
        ssh_config_file.write("##########################\n\n")

        """
        We iterate the results and read the tags for each instance.
        Using those tags we create an ssh config entry for each instance.
        and append it to the config file.

        host <client>.<environment>.<name>
            Hostname <ec2-public-ip>
            IdentityFile <path_to_ssh_key>

        """
        for page in response_iterator:
            for reservation in page['Reservations']:
                for instance in reservation['Instances']:
                    try:
                        host_line = ""
                        host = ""
                        env = ""
                        try:
                            public_ip = instance['PublicIpAddress']
                        except KeyError:
                            try:
                                public_ip = instance['PrivateIpAddress']
                            except KeyError:
                                sys.stderr.write(
                                    'Cannot lookup ip address for instance %s,'
                                    ' skipped it.'
                                    % instance['InstanceId'])
                                continue
                        for tag in instance['Tags']:
                            if tag['Key'] == "Name":
                                name = tag['Value']

                        host = "{}".format(name).replace(" ", "-")
                        host_line += "host {}\n".format(host.lower())
                        host_line += "    Hostname {}\n".format(public_ip)
                        host_line += "    IdentityFile {}\n".format(
                            path_to_ssh_key)
                        ssh_config_file.write(host_line)
                    except Exception as e:
                        raise e

        print("File updated: " + os.path.expanduser('~') + path_to_config)
    except Exception as e:
        print(e)

if __name__ == '__main__':
    main()