test_dns_records.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright 2017, Florent Thiery
'''
Checks that DNS records are provided by the customer servers are correctly set
'''
import subprocess
import os
import sys
import imp

GREEN = '\033[92m'
RED = '\033[91m'
DEF = '\033[0m'


def get_dns_servers():
    servers = list()
    with open('/etc/resolv.conf', 'r') as f:
        d = f.read().strip()
        for l in d.split('\n'):
            if l.startswith('nameserver '):
                servers.append(l.split('nameserver ')[1])
    return servers

resolvers = get_dns_servers()


def get_result(output):
    for line in output.split('\n'):
        if "has address " in line:
            return line.split("has address ")[1]


def check_dns(hostname, expected_ip):
    all_ok = True
    for resolver in resolvers:
        status, output = subprocess.getstatusoutput("host %s %s" % (hostname, resolver))
        success = (status == 0)
        if success:
            color = GREEN
            address = get_result(output)
            if address != expected_ip:
                print('Expected ip was: %s, got %s' % (expected_ip, address))
                color = RED
                all_ok = False
        else:
            color = RED
            all_ok = False
            address = "FAIL"
        print('%sDNS resolution of %s on server %s returned %s%s' % (color, hostname, resolver, address, DEF))
    return all_ok


os.chdir(os.path.dirname(__file__))
if os.path.isfile('../utils.py'):
    all_ok = True
    es_utils = imp.load_source('es_utils', '../utils.py')
    conf = es_utils.load_conf()

    ip = conf.get('NETWORK_IP_NAT')
    if not ip or ip == '0':
        ip = conf.get('NETWORK_IP')

    conf_resolvers_keys = (
        'NETWORK_DNS1',
        'NETWORK_DNS2',
    )
    for conf_resolver_key in conf_resolvers_keys:
        conf_resolver = conf.get(conf_resolver_key)
        if conf_resolver and conf_resolver != '0' and conf_resolver not in resolvers:
            print('Resolver %s not configured on the system' % conf_resolver)
            all_ok = False
     
    conf_servers = (
        'MS_SERVER_NAME',
        'MONITOR_SERVER_NAME',
        'CM_SERVER_NAME',
    )
    for s in conf_servers:
        hostname = conf.get(s)
        ok = check_dns(hostname, ip)
        if not ok:
            all_ok = False
else:
    print('conf.sh not found')
    sys.exit(1)

if not all_ok:
    sys.exit(1)
else:
    sys.exit(0)