issh - CLI script to access an EC2 instance via SSH using the instance ID

README.md

Luzifer / issh

I was tired to search the IP for an autoscaling or ELB instance in the EC2 instances table, copy and then SSH to it so I wrote a small script to help me with this. The goal was to provide just the instance ID (and if required also username and port) to ssh into the instance.

Requirements

• Python 2 (Tested 2.7)
• boto

Demo

luzifer@knut-workstation01 ~> issh -u ubuntu i-7f98d53c
Welcome to Ubuntu 14.04.1 LTS (GNU/Linux 3.13.0-35-generic x86_64)
[...]
ubuntu@ip-10-5-40-97:~$ logout
Connection to 10.5.40.97 closed.
luzifer@knut-workstation01 ~>

Help

luzifer@knut-workstation01 ~> issh -h
usage: issh [-h] [-p port] [-u user] instance_id

Searches instance IP and connects via SSH

positional arguments:
  instance_id  ID of the instance in format "i-XXXXX"

optional arguments:
  -h, --help   show this help message and exit
  -p port      Port to connect to (default 22)
  -u user      User to use for connection (default current username)
luzifer@knut-workstation01 ~>

issh.py

#!/usr/bin/env python2

import os, sys, argparse, boto.ec2

def main():
  parser = argparse.ArgumentParser(description='Searches instance IP and connects via SSH')
  parser.add_argument('-p', type=int, default=22, metavar='port', help='Port to connect to (default 22)')
  parser.add_argument('-u', type=str, default=None, metavar='user', help='User to use for connection (default current username)')
  parser.add_argument('instance_id', type=str, help='ID of the instance in format "i-XXXXX"')
  args = parser.parse_args()

  if None in [os.getenv('EC2_REGION'), os.getenv('AWS_ACCESS_KEY_ID'), os.getenv('AWS_SECRET_ACCESS_KEY')]:
    print 'Please provide these environment variables: EC2_REGION, AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY'
    sys.exit(1)

  if os.getenv('EC2_REGION') not in [r.name for r in boto.ec2.regions()]:
    print 'Region "{}" derived from environment variable EC2_REGION is not a valid region.'.format(os.getenv('EC2_REGION'))
    sys.exit(1)

  ec2_connection = boto.ec2.connect_to_region(os.getenv('EC2_REGION'),
    aws_access_key_id=os.getenv('AWS_ACCESS_KEY_ID'), 
    aws_secret_access_key=os.getenv('AWS_SECRET_ACCESS_KEY'))

  instances = ec2_connection.get_only_instances([args.instance_id])
  if len(instances) != 1:
    print 'Did not found a single instance for ID {}'.format(args.instance_id)
    sys.exit(1)
  instance = instances[0]

  if instance.private_ip_address is not None:
    _call_ssh(instance.private_ip_address, args.u, args.p)
  else:
    _call_ssh(instance.ip_address, args.u, args.p)

def _call_ssh(ip, user=None, port=None):
  args = ['/usr/bin/ssh']
  if port is not None:
    args.append('-p {}'.format(port))
  if user is not None:
    args.append('{}@{}'.format(user, ip))
  else:
    args.append('{}'.format(ip))
    
  os.execv('/usr/bin/ssh', args)

if __name__ == '__main__':
  main()