140 lines
4.5 KiB
ReStructuredText
140 lines
4.5 KiB
ReStructuredText
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Copyright 2016 Hewlett Packard Enterprise Development Company LP
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Licensed under the Apache License, Version 2.0 (the "License"); you may
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not use this file except in compliance with the License. You may obtain
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a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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License for the specific language governing permissions and limitations
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under the License.
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.. _pools:
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================
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DNS Server Pools
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================
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Overview
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========
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In designate we support the concept of multiple "pools" of DNS Servers.
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This allows operators to scale out their DNS Service by adding more pools, avoiding
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the scalling problems that some DNS servers have for number of zones, and the total
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number of records hosted by a single server.
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This also allows providers to have tiers of service (i.e. the difference
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between GOLD vs SILVER tiers may be the number of DNS Servers, and how they
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are distributed around the world.)
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In a private cloud situation, it allows operators to separate internal and
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external facing zones.
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To help users create zones on the correct pool we have a "scheduler" that is
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responsible for examining the zone being created and the pools that are
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available for use, and matching the zone to a pool.
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The filters are pluggable (i.e. operator replaceable) and all follow a simple
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interface.
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The zones are matched using "zone attributes" and "pool attributes". These are
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key: value pairs that are attached to the zone when it is being created, and
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the pool. The pool attributes can be updated by the operator in the future,
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but it will **not** trigger zones to be moved from one pool to another.
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.. note::
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Currently the only zone attribute that is accepted is the `pool_id` attribute.
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As more filters are merged there will be support for dynamic filters.
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Target vs. Nameserver
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=====================
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One thing that can be confusing about pools is the differentiation
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between a target and a nameserver. The target is where Designate will
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try to write the change, while a namserver is where Designate checks
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that the change exists.
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A great example of this is `bind's stealth master system
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<http://www.zytrax.com/books/dns/ch4/#stealth>`_. In this
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configuration, there could be a stealth master that you configure as
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your target and a set of slaves pointed to that master as your
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nameservers. Designate will write to the master and then look for the
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changes on the slaves before considering the change active.
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Another example would be where Designate uses an API backend such as
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DynDNS or even another Designate instance. In this situation, you will
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typically have a single target with a set of nameservers to test that
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meet your requirements.
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Yet another example is when using a Designate agent. In this scenario
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your agent instances are the targets and the nameservers the agent
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updates would be checked for the correct information.
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Managing Pools
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==============
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In mitaka we moved the method of updating pools to a CLI in `designate-manage`
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There is a YAML file that defines the pool, and is used to load this information into the database.
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.. literalinclude:: ../../etc/designate/pools.yaml.sample
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:language: yaml
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Designate Manage Pools Command Reference
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----------------------------------------
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Update Pools Information
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^^^^^^^^^^^^^^^^^^^^^^^^
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.. code-block:: console
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designate-manage pool update [options]
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Options:
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""""""""
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--file Input file (Default: ``/etc/designate/pools.yaml``)
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--dry_run Simulate an update. (Default: False)
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--delete Delete Pools that are not in the input file (Defaults: False)
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.. warning::
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| Running with ``--delete True`` can be **extremely** dangerous.
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| It will delete any pools that are not in the supplied YAML file, and any
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| zones that are in that Pool.
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| Before running with ``--delete True`` we recommend operators run with
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| ``--delete True --dry_run True`` to view the outcome.
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Generate YAML File
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^^^^^^^^^^^^^^^^^^
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.. code-block:: console
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designate-manage pool generate_file [options]
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Options:
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""""""""
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--file YAML file output too (Default: ``/etc/designate/pools.yaml``)
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Generate YAML File from Liberty Config
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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.. code-block:: console
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designate-manage pool export_from_config [options]
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Options:
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""""""""
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--file YAML file output too (Default: ``/etc/designate/pools.yaml``)
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