diskimage-builder/diskimage_builder/elements/no-final-image/README.rst

==============
no-final-image
==============

This is a noop element which can be used to indicate to diskimage-builder that
it should not bother creating a final image out of the generated filesystem.
It is useful in cases where an element handles all of the image building
itself, such as ironic-python-agent-ramdisk or Docker images.  In those cases
the final image normally generated by diskimage-builder is not the desired
output, so there's no reason to spend time creating it.

Elements that wish to behave this way should include this element in their
element-deps file.
Generalize logic for skipping final image generation Since the ironic-agent element builds the ramdisk and extracts the kernel itself, there's no need to actually generate an image at the end of the process. Previously the unnecessary image was being deleted, but this wastes a bunch of time compressing and converting the image. It's better to just not create the image at all. This change adds a noop element called no-final-image that disk-image-create looks for in the element list and, if found, will cause it to skip the final image generation. This is more flexible than the previous ironic-agent-specific method that would have required changes to disk-image-create for every element that wanted to behave similarly. Note that this cannot be done using an environment variable, because element environments.d entries do not propagate out to disk-image-create. It also doesn't make sense as a user option because it should be set by the element author, not the user. Change-Id: I168feb18f0d578b3babbe4784d3ef75e755e1ebd 2016-06-24 18:29:19 +00:00			`==============`
			`no-final-image`
			`==============`

			`This is a noop element which can be used to indicate to diskimage-builder that`
			`it should not bother creating a final image out of the generated filesystem.`
			`It is useful in cases where an element handles all of the image building`
Remove the deprecated ironic-agent element Despite having several issues (like missing firmware), it is still used by people. It seems that the only way to stop that is to remove it. Change-Id: I4baed8e8ab663c624dcc8d06ff0293d57b082abb 2021-01-21 13:06:08 +00:00			`itself, such as ironic-python-agent-ramdisk or Docker images. In those cases`
			`the final image normally generated by diskimage-builder is not the desired`
			`output, so there's no reason to spend time creating it.`
Generalize logic for skipping final image generation Since the ironic-agent element builds the ramdisk and extracts the kernel itself, there's no need to actually generate an image at the end of the process. Previously the unnecessary image was being deleted, but this wastes a bunch of time compressing and converting the image. It's better to just not create the image at all. This change adds a noop element called no-final-image that disk-image-create looks for in the element list and, if found, will cause it to skip the final image generation. This is more flexible than the previous ironic-agent-specific method that would have required changes to disk-image-create for every element that wanted to behave similarly. Note that this cannot be done using an environment variable, because element environments.d entries do not propagate out to disk-image-create. It also doesn't make sense as a user option because it should be set by the element author, not the user. Change-Id: I168feb18f0d578b3babbe4784d3ef75e755e1ebd 2016-06-24 18:29:19 +00:00
			`Elements that wish to behave this way should include this element in their`
			`element-deps file.`