postgresql-sync.py

# coding: utf-8
from datetime import datetime
from time import sleep
from sys import exit

from psycopg2 import connect, OperationalError


def wait_for_database(delay=4, retries=10, host='db', dbname='postgres',
                      user='postgres'):
    for _ in range(retries):
        try:
            connection = connect(host=host, dbname=dbname, user=user)
        except OperationalError:
            print("Couldn't connect to PostgreSQL at <%s>, retrying in %d s." %
                  (datetime.now(), delay))
            sleep(delay)
        else:
            print("Succesfully connected to PostgreSQL.")
            connection.close()
            return 0

    print("Error: maximum number of retries (%d) reached." % retries)
    return -1

if __name__ == '__main__':
    exit(wait_for_database())