buildextend-installer: ship live PXE artifacts inside live ISO #1643
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We're going to be implementing the ISO image in terms of the rootfs, so this option will no longer provide any savings.
Personal Opinion: I'm fine with that assuming we coordinate the changes and try to keep downtime minimalish. |
Its contents are already compressed, and we can use the lack of a compression wrapper to unify the ISO and PXE images. It turns out that the kernel allows uncompressed appended initrds, we just need to pad the previous image to a 4-byte boundary.
Requires fedora-coreos-config/live bootloader config changes to append /images/ignition.img as an additional initrd.
It seems to be conventional in Fedora/RHEL to put the kernel in /images/pxeboot/vmlinuz and the initramfs in /images/pxeboot/initrd.img. Requires matching fedora-coreos-config/live bootloader config changes.
Embed bit-for-bit copies of the initrd and rootfs in the ISO so that users can copy them out again. Place the squashfs at the beginning of the rootfs image so 20live can find it. Always keep the osmet files in the rootfs and the rootfs stream hash in the base initrd.
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Okay, CI is green, and I've dropped the last /hold |
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/lgtm |
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/override continuous-integration/jenkins/pr-merge |
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@dustymabe discovered that the kernel does allow uncompressed appended initrds; it just needs them to start on a 4-byte boundary. This allows us to refactor the live ISO as a wrapper around bit-for-bit copies of the live PXE artifacts. That's useful because Fedora and RHEL users may expect to be able to copy PXE artifacts out of the ISO image.
Switch to an uncompressed rootfs image; pad the initramfs image appropriately so the two can still be concatenated. Move the ISO Ignition padding area to a separate file so the PXE initramfs artifact doesn't need to include padding. Move the kernel and initramfs to the paths within the ISO that Fedora and RHEL conventionally use, and put the rootfs image next to them. Put the rootfs stream hash in the initrd, and the osmet files in the rootfs, for both sets of artifacts.
There are several changes here that interlock with fedora-coreos-config, and no ratchet. I've temporarily added a commit to run cosa CI against coreos/fedora-coreos-config#548, but I propose that we ultimately merge over red and accept the transient CI break.