7705b0b2d6
Remove the sphinxcontrib-seqdiag dependency as the Pillow upgrade to version 10.x (from OpenStack upper constraints) breaks its usage. In the ironic source docs, reference the svg files in the rst files, and keep the .diag files in the doc/source/images/ directory as backup. Closes-Bug: #2026345 Change-Id: I54cea22e963441b729d4201ad9f8a055a65b54f8
83 lines
2.9 KiB
ReStructuredText
83 lines
2.9 KiB
ReStructuredText
.. _agent_token:
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===========
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Agent Token
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===========
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Purpose
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=======
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The concept of agent tokens is to provide a mechanism by which the
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relationship between an operating deployment of the Bare Metal Service
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and an instance of the ``ironic-python-agent`` is verified. In a sense,
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this token can be viewed as a session identifier or authentication token.
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.. warning::
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This functionality does not remove the risk of a man-in-the-middle attack
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that could occur from connection intercept or when TLS is not used for
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all communication.
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This becomes useful in the case of deploying an "edge" node where intermediate
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networks are not trustworthy.
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How it works
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============
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These tokens are provided in one of two ways to the running agent.
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1. A pre-generated token which is embedded into virtual media ISOs.
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2. A one-time generated token that are provided upon the first "lookup"
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of the node.
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In both cases, the tokens are a randomly generated using the Python
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``secrets`` library. As of mid-2020, the default length is 43 characters.
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Once the token has been provided, the token cannot be retrieved or accessed.
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It remains available to the conductors, and is stored in memory of the
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``ironic-python-agent``.
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.. note::
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In the case of the token being embedded with virtual media, it is read
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from a configuration file with-in the image. Ideally this should be paired
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with Swift temporary URLs.
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With the token is available in memory in the agent, the token is embedded with
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``heartbeat`` operations to the ironic API endpoint. This enables the API to
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authenticate the heartbeat request, and refuse "heartbeat" requests from the
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``ironic-python-agent``. As of the Victoria release, use of Agent Token is
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required for all agents and the previously available setting to force this
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functionality to be mandatory, ``[DEFAULT]require_agent_token`` no longer has
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any effect.
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.. warning::
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If the Bare Metal Service is updated, and the version of
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``ironic-python-agent`` should be updated to enable this feature.
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In addition to heartbeats being verified, commands from the
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``ironic-conductor`` service to the ``ironic-python-agent`` also include the
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token, allowing the agent to authenticate the caller.
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With Virtual Media
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------------------
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.. figure:: ./../images/agent-token-with-virtual-media.svg
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:width: 100%
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With PXE/iPXE/etc.
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------------------
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.. figure:: ./../images/agent-token-with-pxe-ipxe.svg
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:width: 100%
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Agent Configuration
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===================
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An additional setting which may be leveraged with the ``ironic-python-agent``
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is a ``agent_token_required`` setting. Under normal circumstances, this
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setting can be asserted via the configuration supplied from the Bare Metal
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service deployment upon the ``lookup`` action, but can be asserted via the
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embedded configuration for the agent in the ramdisk. This setting is also
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available via kernel command line as ``ipa-agent-token-required``.
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