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))
        if status == 0:
            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 not os.path.isfile('../utils.py'):
    print('conf.sh not found')
    sys.exit(1)

es_utils = imp.load_source('es_utils', '../utils.py')
conf = es_utils.load_conf()

all_ok = True
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

ip = conf.get('NETWORK_IP_NAT')
if not ip or ip == '0':
    ip = conf.get('NETWORK_IP')
if not ip or ip == '0':
    if not all_ok:
        sys.exit(1)
    print('No IP set in configuration file, unable to test DNS.')
    sys.exit(2)

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

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