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[network] Configure DNS resolution 

Configure DNS resolution for instances.

Closes-Bug: #1541192

Co-Authored-By: Matt Kassawara <mkassawara@gmail.com>

Change-Id: I7e536291bb0966969b3153481c734f71cb3cad5f
(cherry picked from commit f3eff8dfa9)
This commit is contained in:
Robin Cernin 2016-05-12 10:30:13 +02:00 committed by venkatamahesh
parent e752ead8a7
commit 41d65e5458
2 changed files with 98 additions and 0 deletions
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97
doc/networking-guide/source/config-dns-resolution.rst Normal file
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.. _config-dns-resolution:
=============================
Name resolution for instances
=============================
The Networking service offers several methods to configure name
resolution (DNS) for instances. Most deployments should implement
case 1 or 2. Case 3 requires security considerations to prevent
leaking internal DNS information to instances.
Case 1: Each virtual network uses unique DNS resolver(s)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In this case, the DHCP agent offers one or more unique DNS resolvers
to instances via DHCP on each virtual network. You can configure a DNS
resolver when creating or updating a subnet. To configure more than
one DNS resolver, use a comma between each value.
* Configure a DNS resolver when creating a subnet.
.. code-block:: console
$ neutron subnet-create --dns-nameserver DNS_RESOLVER
Replace ``DNS_RESOLVER`` with the IP address of a DNS resolver reachable
from the virtual network. For example:
.. code-block:: console
$ neutron subnet-create --dns-nameserver 8.8.8.8,8.8.4.4
.. note::
This command requires other options outside the scope of this
content.
* Configure a DNS resolver on an existing subnet.
.. code-block:: console
$ neutron subnet-update --dns-nameserver DNS_RESOLVER SUBNET_ID_OR_NAME
Replace ``DNS_RESOLVER`` with the IP address of a DNS resolver reachable
from the virtual network and ``SUBNET_ID_OR_NAME`` with the UUID or name
of the subnet. For example, using the ``selfservice`` subnet:
.. code-block:: console
$ neutron subnet-update --dns-nameserver 8.8.8.8,8.8.4.4 selfservice
Case 2: All virtual networks use same DNS resolver(s)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In this case, the DHCP agent offers the same DNS resolver(s) to
instances via DHCP on all virtual networks.
* In the ``dhcp_agent.ini`` file, configure one or more DNS resolvers. To
configure more than one DNS resolver, use a comma between each value.
.. code-block:: ini
[DEFAULT]
dnsmasq_dns_servers = DNS_RESOLVER
Replace ``DNS_RESOLVER`` with the IP address of a DNS resolver reachable
from all virtual networks. For example:
.. code-block:: ini
[DEFAULT]
dnsmasq_dns_servers = 8.8.8.8, 8.8.4.4
.. note::
You must configure this option for all eligible DHCP agents and
restart them to activate the values.
Case 3: All virtual networks use DNS resolver(s) on the host
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In this case, the DHCP agent offers the DNS resolver(s) in the
``resolv.conf`` file on the host running the DHCP agent via DHCP to
instances on all virtual networks.
* In the ``dhcp_agent.ini`` file, enable advertisement of the DNS resolver(s)
on the host.
.. code-block:: ini
[DEFAULT]
dnsmasq_local_resolv = True
.. note::
You must configure this option for all eligible DHCP agents and
restart them to activate the values.

1
doc/networking-guide/source/config.rst
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@ -11,3 +11,4 @@ the `Configuration Reference
config-server.rst
config-ml2-plug-in.rst
config-dns-resolution.rst