Make dnsmasq aware of all names
Each dnsmasq instance on a network is not aware of other dnsmasq's leases. When dnsmasq is launched with --no-hosts and is not provided an --addn-hosts file, it can resolve only the hosts to which it gives a dhcp lease and no more. i.e.: If dnsmasq service n°1 gives a lease to instance n°1, and dnsmasq service n°2 gives a lease to instance n°2, both VM instances and dnsmasq services being on the same network: instance n°1 can not resolve instance n°2, because instance n°1 queries dnsmasq n°1, and since it did not give the lease to instance n°2, it can not resolve it (it is not aware of its existence). Same issue if instance n°2 tries to resolve instance n°1. The solution is to provide dnsmasq with an --addn-hosts file of all hosts on the network. With an --addn-hosts file, each dnsmasq instance is aware of all the hosts on the network even if they do not give the lease for a host, therefore each dnsmasq instance can resolve any host on their network even if they did not provide the lease for it themselves. Change-Id: Ic6d4f7854d250889dded5491e4693fcdce32ed00 Fixes: bug #1242712
This commit is contained in:
Yves-Gwenael Bourhis
parent
1ed0b46373
commit
c1402b22a6
@ -324,6 +324,7 @@ class Dnsmasq(DhcpLocalProcess):
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'--pid-file=%s' % self.get_conf_file_name(
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'pid', ensure_conf_dir=True),
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'--dhcp-hostsfile=%s' % self._output_hosts_file(),
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'--addn-hosts=%s' % self._output_addn_hosts_file(),
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'--dhcp-optsfile=%s' % self._output_opts_file(),
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'--leasefile-ro',
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]
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@ -390,6 +391,7 @@ class Dnsmasq(DhcpLocalProcess):
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self._release_unused_leases()
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self._output_hosts_file()
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self._output_addn_hosts_file()
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self._output_opts_file()
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if self.active:
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cmd = ['kill', '-HUP', self.pid]
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@ -399,40 +401,67 @@ class Dnsmasq(DhcpLocalProcess):
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LOG.debug(_('Reloading allocations for network: %s'), self.network.id)
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self.device_manager.update(self.network)
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def _iter_hosts(self):
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"""Iterate over hosts.
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For each host on the network we yield a tuple containing:
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(
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port, # a DictModel instance representing the port.
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alloc, # a DictModel instance of the allocated ip and subnet.
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host_name, # Host name.
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name, # Host name and domain name in the format 'hostname.domain'.
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)
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"""
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for port in self.network.ports:
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for alloc in port.fixed_ips:
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hostname = 'host-%s' % alloc.ip_address.replace(
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'.', '-').replace(':', '-')
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fqdn = '%s.%s' % (hostname, self.conf.dhcp_domain)
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yield (port, alloc, hostname, fqdn)
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def _output_hosts_file(self):
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"""Writes a dnsmasq compatible hosts file."""
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r = re.compile('[:.]')
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"""Writes a dnsmasq compatible dhcp hosts file.
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The generated file is sent to the --dhcp-hostsfile option of dnsmasq,
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and lists the hosts on the network which should receive a dhcp lease.
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Each line in this file is in the form::
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'mac_address,FQDN,ip_address'
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IMPORTANT NOTE: a dnsmasq instance does not resolve hosts defined in
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this file if it did not give a lease to a host listed in it (e.g.:
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multiple dnsmasq instances on the same network if this network is on
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multiple network nodes). This file is only defining hosts which
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should receive a dhcp lease, the hosts resolution in itself is
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defined by the `_output_addn_hosts_file` method.
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"""
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buf = six.StringIO()
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filename = self.get_conf_file_name('host')
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LOG.debug(_('Building host file: %s'), filename)
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for (port, alloc, hostname, name) in self._iter_hosts():
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set_tag = ''
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# (dzyu) Check if it is legal ipv6 address, if so, need wrap
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# it with '[]' to let dnsmasq to distinguish MAC address from
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# IPv6 address.
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ip_address = alloc.ip_address
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if netaddr.valid_ipv6(ip_address):
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ip_address = '[%s]' % ip_address
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for port in self.network.ports:
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for alloc in port.fixed_ips:
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name = 'host-%s.%s' % (r.sub('-', alloc.ip_address),
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self.conf.dhcp_domain)
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set_tag = ''
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# (dzyu) Check if it is legal ipv6 address, if so, need wrap
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# it with '[]' to let dnsmasq to distinguish MAC address from
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# IPv6 address.
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ip_address = alloc.ip_address
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if netaddr.valid_ipv6(ip_address):
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ip_address = '[%s]' % ip_address
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LOG.debug(_('Adding %(mac)s : %(name)s : %(ip)s'),
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{"mac": port.mac_address, "name": name,
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"ip": ip_address})
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LOG.debug(_('Adding %(mac)s : %(name)s : %(ip)s'),
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{"mac": port.mac_address, "name": name,
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"ip": ip_address})
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if getattr(port, 'extra_dhcp_opts', False):
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if self.version >= self.MINIMUM_VERSION:
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set_tag = 'set:'
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if getattr(port, 'extra_dhcp_opts', False):
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if self.version >= self.MINIMUM_VERSION:
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set_tag = 'set:'
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buf.write('%s,%s,%s,%s%s\n' %
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(port.mac_address, name, ip_address,
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set_tag, port.id))
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else:
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buf.write('%s,%s,%s\n' %
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(port.mac_address, name, ip_address))
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buf.write('%s,%s,%s,%s%s\n' %
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(port.mac_address, name, ip_address,
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set_tag, port.id))
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else:
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buf.write('%s,%s,%s\n' %
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(port.mac_address, name, ip_address))
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utils.replace_file(filename, buf.getvalue())
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LOG.debug(_('Done building host file %s'), filename)
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@ -459,6 +488,25 @@ class Dnsmasq(DhcpLocalProcess):
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for ip, mac in old_leases - new_leases:
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self._release_lease(mac, ip)
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def _output_addn_hosts_file(self):
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"""Writes a dnsmasq compatible additional hosts file.
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The generated file is sent to the --addn-hosts option of dnsmasq,
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and lists the hosts on the network which should be resolved even if
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the dnsmaq instance did not give a lease to the host (see the
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`_output_hosts_file` method).
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Each line in this file is in the same form as a standard /etc/hosts
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file.
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"""
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buf = six.StringIO()
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for (port, alloc, hostname, fqdn) in self._iter_hosts():
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# It is compulsory to write the `fqdn` before the `hostname` in
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# order to obtain it in PTR responses.
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buf.write('%s\t%s %s\n' % (alloc.ip_address, fqdn, hostname))
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addn_hosts = self.get_conf_file_name('addn_hosts')
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utils.replace_file(addn_hosts, buf.getvalue())
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return addn_hosts
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def _output_opts_file(self):
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"""Write a dnsmasq compatible options file."""
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@ -672,6 +672,7 @@ class TestDnsmasq(TestBase):
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'--except-interface=lo',
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'--pid-file=/dhcp/%s/pid' % network.id,
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'--dhcp-hostsfile=/dhcp/%s/host' % network.id,
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'--addn-hosts=/dhcp/%s/addn_hosts' % network.id,
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'--dhcp-optsfile=/dhcp/%s/opts' % network.id,
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'--leasefile-ro']
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@ -962,7 +963,8 @@ tag:44444444-4444-4444-4444-444444444444,option:bootfile-name,pxelinux3.0"""
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self.safe.assert_called_once_with('/foo/opts', expected)
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def test_reload_allocations(self):
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@property
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def _test_reload_allocation_data(self):
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exp_host_name = '/dhcp/cccccccc-cccc-cccc-cccc-cccccccccccc/host'
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exp_host_data = ('00:00:80:aa:bb:cc,host-192-168-0-2.openstacklocal,'
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'192.168.0.2\n'
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@ -974,8 +976,23 @@ tag:44444444-4444-4444-4444-444444444444,option:bootfile-name,pxelinux3.0"""
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'openstacklocal,[fdca:3ba5:a17a:4ba3::3]\n'
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'00:00:0f:rr:rr:rr,host-192-168-0-1.openstacklocal,'
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'192.168.0.1\n').lstrip()
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exp_addn_name = '/dhcp/cccccccc-cccc-cccc-cccc-cccccccccccc/addn_hosts'
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exp_addn_data = (
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'192.168.0.2\t'
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'host-192-168-0-2.openstacklocal host-192-168-0-2\n'
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'fdca:3ba5:a17a:4ba3::2\t'
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'host-fdca-3ba5-a17a-4ba3--2.openstacklocal '
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'host-fdca-3ba5-a17a-4ba3--2\n'
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'192.168.0.3\thost-192-168-0-3.openstacklocal '
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'host-192-168-0-3\n'
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'fdca:3ba5:a17a:4ba3::3\t'
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'host-fdca-3ba5-a17a-4ba3--3.openstacklocal '
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'host-fdca-3ba5-a17a-4ba3--3\n'
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'192.168.0.1\t'
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'host-192-168-0-1.openstacklocal '
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'host-192-168-0-1\n'
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).lstrip()
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exp_opt_name = '/dhcp/cccccccc-cccc-cccc-cccc-cccccccccccc/opts'
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exp_opt_data = "tag:tag0,option:router,192.168.0.1"
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fake_v6 = 'gdca:3ba5:a17a:4ba3::1'
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fake_v6_cidr = 'gdca:3ba5:a17a:4ba3::/64'
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exp_opt_data = """
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@ -988,6 +1005,14 @@ tag:tag1,option:classless-static-route,%s,%s
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tag:tag1,249,%s,%s""".lstrip() % (fake_v6,
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fake_v6_cidr, fake_v6,
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fake_v6_cidr, fake_v6)
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return (exp_host_name, exp_host_data,
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exp_addn_name, exp_addn_data,
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exp_opt_name, exp_opt_data,)
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def test_reload_allocations(self):
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(exp_host_name, exp_host_data,
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exp_addn_name, exp_addn_data,
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exp_opt_name, exp_opt_data,) = self._test_reload_allocation_data
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exp_args = ['kill', '-HUP', 5]
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@ -1008,36 +1033,14 @@ tag:tag1,249,%s,%s""".lstrip() % (fake_v6,
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self.assertTrue(ip_map.called)
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self.safe.assert_has_calls([mock.call(exp_host_name, exp_host_data),
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mock.call(exp_addn_name, exp_addn_data),
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mock.call(exp_opt_name, exp_opt_data)])
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self.execute.assert_called_once_with(exp_args, 'sudo')
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def test_reload_allocations_stale_pid(self):
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exp_host_name = '/dhcp/cccccccc-cccc-cccc-cccc-cccccccccccc/host'
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exp_host_data = ('00:00:80:aa:bb:cc,host-192-168-0-2.openstacklocal,'
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'192.168.0.2\n'
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'00:00:f3:aa:bb:cc,host-fdca-3ba5-a17a-4ba3--2.'
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'openstacklocal,[fdca:3ba5:a17a:4ba3::2]\n'
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'00:00:0f:aa:bb:cc,host-192-168-0-3.openstacklocal,'
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'192.168.0.3\n'
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'00:00:0f:aa:bb:cc,host-fdca-3ba5-a17a-4ba3--3.'
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'openstacklocal,[fdca:3ba5:a17a:4ba3::3]\n'
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'00:00:0f:rr:rr:rr,host-192-168-0-1.openstacklocal,'
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'192.168.0.1\n').lstrip()
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exp_host_data.replace('\n', '')
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exp_opt_name = '/dhcp/cccccccc-cccc-cccc-cccc-cccccccccccc/opts'
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exp_opt_data = "tag:tag0,option:router,192.168.0.1"
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fake_v6 = 'gdca:3ba5:a17a:4ba3::1'
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fake_v6_cidr = 'gdca:3ba5:a17a:4ba3::/64'
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exp_opt_data = """
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tag:tag0,option:dns-server,8.8.8.8
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tag:tag0,option:classless-static-route,20.0.0.1/24,20.0.0.1
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tag:tag0,249,20.0.0.1/24,20.0.0.1
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tag:tag0,option:router,192.168.0.1
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tag:tag1,option:dns-server,%s
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tag:tag1,option:classless-static-route,%s,%s
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tag:tag1,249,%s,%s""".lstrip() % (fake_v6,
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fake_v6_cidr, fake_v6,
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fake_v6_cidr, fake_v6)
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(exp_host_name, exp_host_data,
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exp_addn_name, exp_addn_data,
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exp_opt_name, exp_opt_data,) = self._test_reload_allocation_data
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with mock.patch('__builtin__.open') as mock_open:
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mock_open.return_value.__enter__ = lambda s: s
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@ -1057,9 +1060,11 @@ tag:tag1,249,%s,%s""".lstrip() % (fake_v6,
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dm.reload_allocations()
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self.assertTrue(ipmap.called)
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self.safe.assert_has_calls([mock.call(exp_host_name,
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exp_host_data),
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mock.call(exp_opt_name, exp_opt_data)])
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self.safe.assert_has_calls([
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mock.call(exp_host_name, exp_host_data),
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mock.call(exp_addn_name, exp_addn_data),
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mock.call(exp_opt_name, exp_opt_data),
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])
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mock_open.assert_called_once_with('/proc/5/cmdline', 'r')
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def test_release_unused_leases(self):
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