Wait for port

wait_for_port.py

#!/usr/bin/env python

import os
import sys
import time
import telnetlib

check_timeout = int(os.environ.get('CHECK_TIMEOUT', 1))
sleep_interval = int(os.environ.get('SLEEP_INTERVAL', 1))
port_to_check = int(os.environ.get('PORT_TO_CHECK'))
max_retries = int(os.environ.get('MAX_RETRIES', 20))
host = os.environ.get('HOST', 'localhost')

failed_attempts = 0
successful_attempts = 0

for _ in range(max_retries):
    try:
        conn = telnetlib.Telnet(host, port_to_check, check_timeout)
        successful_attempts += 1
        sys.stdout.write('Port %s:%s is active. Wil recheck in %s seconds\n' % (
        host, port_to_check, sleep_interval))
        time.sleep(sleep_interval)
    except Exception, e:
        sys.stderr.write('%s\n' % repr(e))
        sys.stdout.write('Sleeping %s sec before checking service status\n' % sleep_interval)
        time.sleep(sleep_interval)

if successful_attempts > failed_attempts:
    sys.stdout.write('Port %s is now active :)\n' % port_to_check)
    sys.exit(0)
else:
    sys.stderr.write('Service dit not started after %s retries\n' % max_retries)
    sys.exit(1)