Wait for SSH Connection to become ready with progress bar when trying to connect to Amazon EC2 server

sshready.py

import subprocess
import boto.ec2
import sys

def _progressBar(state):
    progress_bar = '=' * state
    sys.stdout.write('\r'+progress_bar)
    sys.stdout.flush()

# recursive function to wait until the ssh connection is ready
def _awaitAWSInstanceSSHReady(instance, loops):
    time_interval = 5
    key_path = '.uwa/'+AWS_REGION + '/'+AWS_SSH_KEY_NAME + '.pem'
    fnull = open(os.devnull, 'w')
    Process = subprocess.Popen(["ssh", "-i", key_path, "-o", "StrictHostKeyChecking no", "ec2-user@"+instance.public_dns_name, "ls"], stdin = fnull, stdout = fnull, stderr = fnull)
    
    Process.poll()

    while (Process.returncode == None):
        loops += 1
        _progressBar(loops)
        time.sleep(time_interval)
        Process.poll()
    
    if (Process.returncode == 0):
        return True
    elif (Process.returncode == 255):
        _progressBar(loops)
        time.sleep(time_interval)
        _awaitAWSInstanceSSHReady(instance, loops + 1)
    else:
        raise Exception('SSH weird error', instance.public_dns_name)