#!/usr/bin/python
import json
import os
import subprocess
import time
import syslog

def ping_redis(cmd):
    output = ''
    while True:
        try:
            output = subprocess.check_output(cmd, shell=True)
        except subprocess.CalledProcessError as e:
            syslog.syslog(syslog.LOG_ERR, 'ping redis failed, cmd : {}'.format(cmd))

        if 'PONG' in output:
            break
        syslog.syslog(syslog.LOG_ERR, 'ping response : {}'.format(output))
        time.sleep(1)

database_config_file = "/var/run/redis/sonic-db/database_config.json"

data = {}
while True:
    if os.path.isfile(database_config_file):
        with open(database_config_file, "r") as read_file:
            data = json.load(read_file)
        break
    time.sleep(1)
    syslog.syslog(syslog.LOG_ERR, 'config file {} does not exist right now'.format(database_config_file))

while True:
    if 'INSTANCES' in data:
        for inst in data["INSTANCES"]:
            port = data["INSTANCES"][inst]["port"]
            cmd = "redis-cli -p " + str(port) + " ping"
            ping_redis(cmd)
        break
    time.sleep(1)
    syslog.syslog(syslog.LOG_ERR, 'config file {} does not have INSTANCES'.format(database_config_file))