582b2e991c
Implement cross-referencing to configuration options through out the Ironic documentation. Closes-Bug: #2076111 Change-Id: I28712a3a92eb7e7d9875e49ea3ed8800168262fe
110 lines
4.9 KiB
ReStructuredText
110 lines
4.9 KiB
ReStructuredText
===================
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Ironic Python Agent
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===================
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Overview
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========
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*Ironic Python Agent* (also often called *IPA* or just *agent*) is a
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Python-based agent which handles *ironic* bare metal nodes in a
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variety of actions such as inspect, configure, clean and deploy images.
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IPA is distributed over nodes and runs, inside of a ramdisk, the
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process of booting this ramdisk on the node.
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For more information see the
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:ironic-python-agent-doc:`ironic-python-agent documentation <>`.
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Drivers
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=======
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Starting with the Kilo release all deploy interfaces (except for fake ones) are
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using IPA. For nodes using the :ref:`direct-deploy` interface, the conductor
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prepares a swift temporary URL or a local HTTP URL for the image. IPA then
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handles the whole deployment process: downloading an image from swift, putting
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it on the machine and doing any post-deploy actions.
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Requirements
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------------
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Using IPA requires it to be present and configured on the deploy ramdisk, see
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:ref:`deploy-ramdisk`
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.. _ipa-proxies:
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Using proxies for image download
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================================
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Overview
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--------
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When using the :ref:`direct-deploy`, IPA supports using proxies for downloading
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the user image. For example, this could be used to speed up download by using
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a caching proxy.
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Steps to enable proxies
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-----------------------
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#. Configure the proxy server of your choice (for example
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`Squid <http://www.squid-cache.org/Doc/>`_,
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`Apache Traffic Server <https://docs.trafficserver.apache.org/en/latest/index.html>`_).
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This will probably require you to configure the proxy server to cache the
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content even if the requested URL contains a query, and to raise the maximum
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cached file size as images can be pretty big. If you have HTTPS enabled in
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swift (see :swift-doc:`swift deployment guide <deployment_guide.html>`),
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it is possible to configure the proxy server to talk to swift via HTTPS
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to download the image, store it in the cache unencrypted and return it to
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the node via HTTPS again. Because the image will be stored unencrypted in
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the cache, this approach is recommended for images that do not contain
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sensitive information. Refer to your proxy server's documentation to
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complete this step.
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#. Set :oslo.config:option:`glance.swift_temp_url_cache_enabled` in the ironic conductor config
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file to ``True``. The conductor will reuse the cached swift temporary URLs
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instead of generating new ones each time an image is requested, so that the
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proxy server does not create new cache entries for the same image, based on
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the query part of the URL (as it contains some query parameters that change
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each time it is regenerated).
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#. Set :oslo.config:option:`glance.swift_temp_url_expected_download_start_delay` option in the
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ironic conductor config file to the value appropriate for your hardware.
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This is the delay (in seconds) from the time of the deploy request (when
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the swift temporary URL is generated) to when the URL is used for the image
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download. You can think of it as roughly the time needed for IPA ramdisk to
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startup and begin download. This value is used to check if the swift
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temporary URL duration is large enough to let the image download begin. Also
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if temporary URL caching is enabled, this will determine if a cached entry
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will still be valid when the download starts. It is used only if
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:oslo.config:option:`glance.swift_temp_url_cache_enabled` is ``True``.
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#. Increase :oslo.config:option:`glance.swift_temp_url_duration` option in the ironic conductor
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config file, as only non-expired links to images will be returned from the
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swift temporary URLs cache. This means that if
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``swift_temp_url_duration=1200`` then after 20 minutes a new image will be
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cached by the proxy server as the query in its URL will change. The value of
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this option must be greater than or equal to
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:oslo.config:option:`glance.swift_temp_url_expected_download_start_delay`.
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#. Add one or more of ``image_http_proxy``, ``image_https_proxy``,
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``image_no_proxy`` to driver_info properties in each node that will use the
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proxy.
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Advanced configuration
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======================
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Out-of-band vs. in-band power off on deploy
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-------------------------------------------
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After deploying an image onto the node's hard disk, Ironic will reboot
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the machine into the new image. By default this power action happens
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``in-band``, meaning that the ironic-conductor will instruct the IPA
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ramdisk to power itself off.
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Some hardware may have a problem with the default approach and
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would require Ironic to talk directly to the management controller
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to switch the power off and on again. In order to tell Ironic to do
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that, you have to update the node's ``driver_info`` field and set the
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``deploy_forces_oob_reboot`` parameter with the value of **True**. For
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example, the below command sets this configuration in a specific node::
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baremetal node set <UUID or name> --driver-info deploy_forces_oob_reboot=True
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