From ffe4417c630537b1fd51292c86877fbea66862fb Mon Sep 17 00:00:00 2001 From: Petr Viktorin Date: Fri, 19 Sep 2014 15:57:44 +0200 Subject: [PATCH] ipa-replica-prepare: Wait for the DNS entry to be resolvable It takes some time after the DNS record is added until it propagates to Bind. In automated installations, it might happen that replica-install is attempted before the hostname is resolvable; in that case the connection check would fail. Wait for the name to be resolvable at the end of replica-prepare. Mention that this can be interrupted (Ctrl+C). Provide an option to skip the wait. In case DNS is not managed by IPA, this reminds the admin of the necessary configuration and checks their work, but it's possible to skip (either by interrupting it interactively, or by the option). https://fedorahosted.org/freeipa/ticket/4551 Reviewed-By: Petr Spacek --- ipaserver/install/ipa_replica_prepare.py | 53 ++++++++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/ipaserver/install/ipa_replica_prepare.py b/ipaserver/install/ipa_replica_prepare.py index 2e91ddd92..7768fd311 100644 --- a/ipaserver/install/ipa_replica_prepare.py +++ b/ipaserver/install/ipa_replica_prepare.py @@ -21,9 +21,12 @@ import os import shutil import tempfile +import time from optparse import OptionGroup from ConfigParser import SafeConfigParser +import dns.resolver + from ipaserver.install import certs, installutils, bindinstance, dsinstance from ipaserver.install.replication import enable_replication_version_checking from ipaserver.plugins.ldap2 import ldap2 @@ -64,6 +67,9 @@ class ReplicaPrepare(admintool.AdminTool): parser.add_option("--ca", dest="ca_file", default=paths.CACERT_P12, metavar="FILE", help="location of CA PKCS#12 file, default /root/cacert.p12") + parser.add_option('--no-wait-for-dns', dest='wait_for_dns', + action='store_false', default=True, + help="do not wait until the replica is resolvable in DNS") group = OptionGroup(parser, "SSL certificate options", "Only used if the server was installed using custom SSL certificates") @@ -290,6 +296,9 @@ class ReplicaPrepare(admintool.AdminTool): if options.ip_address: self.add_dns_records() + if options.wait_for_dns: + self.wait_for_dns() + def copy_ds_certificate(self): options = self.options @@ -452,6 +461,50 @@ class ReplicaPrepare(admintool.AdminTool): raise admintool.ScriptError( "Could not add reverse DNS record for the replica: %s" % e) + def check_dns(self, replica_fqdn): + """Return true if the replica hostname is resolvable""" + resolver = dns.resolver.Resolver() + exceptions = (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer, + dns.resolver.Timeout, dns.resolver.NoNameservers) + + try: + dns_answer = resolver.query(replica_fqdn, 'A', 'IN') + except exceptions: + try: + dns_answer = resolver.query(replica_fqdn, 'AAAA', 'IN') + except exceptions: + return False + except Exception as e: + self.log.warn('Exception while waiting for DNS record: %s: %s', + type(e).__name__, e) + + return True + + def wait_for_dns(self): + options = self.options + + # Make sure replica_fqdn has a trailing dot, so the + # 'search' directive in /etc/resolv.conf doesn't apply + replica_fqdn = self.replica_fqdn + if not replica_fqdn.endswith('.'): + replica_fqdn += '.' + + if self.check_dns(replica_fqdn): + self.log.debug('%s A/AAAA record resolvable', replica_fqdn) + return + + self.log.info('Waiting for %s A or AAAA record to be resolvable', + replica_fqdn) + print 'This can be safely interrupted (Ctrl+C)' + + try: + while not self.check_dns(replica_fqdn): + time.sleep(1) + except KeyboardInterrupt: + self.log.info('Interrupted') + else: + self.log.debug('%s A/AAAA record resolvable', replica_fqdn) + def copy_info_file(self, source, dest): """Copy a file into the info directory