Update refarch with information about image_download_source

Change-Id: Ia06b01e89d79bf0f65d95dd0c20e91b456b8acae
(cherry picked from commit e79f163837)
This commit is contained in:
Dmitry Tantsur 2021-05-03 17:35:26 +02:00
parent 21e618d333
commit 78e10ce59c
2 changed files with 20 additions and 7 deletions

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@ -27,6 +27,8 @@ You can specify this deploy interface when creating or updating a node::
``agent``. This is because before the Kilo release **ironic-python-agent**
used to only support this deploy interface.
.. _image_download_source:
Deploy with custom HTTP servers
-------------------------------

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@ -312,15 +312,26 @@ the space requirements are different:
* The deployment kernel and ramdisk are always cached during the deployment.
* The ``iscsi`` deploy method requires caching of the whole instance image
locally during the deployment. The image has to be converted to the raw
format, which may increase the required amount of disk space, as well as
the CPU load.
* When ``[agent]image_download_source`` is set to ``http`` and Glance is used,
the conductor will download instances images locally to serve them from its
HTTP server. Use ``swift`` to publish images using temporary URLs and convert
them on the node's side.
When ``[agent]image_download_source`` is set to ``local``, it will happen
even for HTTP(s) URLs. For standalone case use ``http`` to avoid unnecessary
caching of images.
In both cases a cached image is converted to raw if ``force_raw_images``
is ``True`` (the default).
.. note::
This is not a concern for the ``direct`` deploy interface, as in this case
the deployment ramdisk downloads the image and either streams it to the
disk or caches it in memory.
``image_download_source`` can also be provided in the node's
``driver_info`` or ``instance_info``. See :ref:`image_download_source`.
* The ``iscsi`` deploy method always requires caching of the whole instance
image locally during the deployment. The image has to be converted to the raw
format, which may increase the required amount of disk space, as well as the
CPU load.
* When network boot is used, the instance image kernel and ramdisk are cached
locally while the instance is active.