iPXE to use Swift Temporary URLs¶
This adds support for generating Swift temporary URLs for the deploy ramdisk and kernel when booting with iPXE.
Currently the iPXE driver requires an external HTTP server to serve
the deploy ramdisk and kernel. When used with Glance, the
ironic-conductor fetches the images from it and place them under the
HTTP root directory, and if a rebalance happens in the hash right the
ironic-conductor taking over the node have to do the same thing,
fetch the images and cache it locally to be able to manage that node.
Having an external HTTP server should not be required when Glance is used with a Swift backend, with Swift we can generate temporary URLs that can be passed to iPXE to download the images without requiring credentials.
The proposed implementation consists in having the iPXE driver to create a Swift tempurl 0 for the deploy ramdisk and kernel that the node will boot as part of the config generation.
This also proposes adding a boolean configuration option under
pxe group called
ipxe_use_swift. If True this will tell iPXE to
not cache the images in the disk and generate the Swift tempurl for the
ramdisk and kernel, if False, iPXE will continue to cache the images
under the HTTP root directory. Defaults to False.
Note that in order to keep compatibility with Nova behavior,
kernel/ramdisk of the user image still have to be cached in case
netboot is required. Doing otherwise will make it impossible for user
to reboot the instance from within when tempurls have expired or the image
is deleted from Glance altogether.
Continue to use an external HTTP server and caching the images on the disk.
Data model impact¶
State Machine Impact¶
REST API impact¶
Client (CLI) impact¶
RPC API impact¶
Driver API impact¶
Nova driver impact¶
There’s a positive security impact because the Swift temporary URLs does have an expiration time and the images in the external HTTP server will be available until the instance is destroyed.
Other end user impact¶
There is a scaling benefit to download directly from Swift since a Swift cluster can be scaled horizontally by adding new nodes.
Other deployer impact¶
Add the new
ipxe_use_swiftconfiguration option under the
Get the PXE driver to generate the Swift temporary URLs as part of the configuration generation when
Skip caching the image on the disk when
Unittests will be added.
Upgrades and Backwards Compatibility¶
The iPXE documentation will be updated to reflect the changes made by this spec.