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Originally, to reflash from Classic to Ubuntu Core, we rebooted with a grub entry that would use specific `root=` and `init=` script to reflash the disk. We do not need a full reboot most of the time and we can just instead prepare an initramfs to switch when shutting down. Systemd will switch to `/run/initramfs` and run `/shutdown` in there. However, on 16.04, systemd is unmounting mounts which makes this not as easy. So instead there we still reboot to grub, but instead of using `init=` and mount the root disk, we provide an initrd which can do the flashing, simplifying the method we have been using.
78 lines
2.3 KiB
Bash
Executable File
78 lines
2.3 KiB
Bash
Executable File
#!/bin/bash
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# flash.sh: Install a flashing process to reboot to a new disk image
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#
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# Copyright (C) 2023-2024 Canonical Ltd
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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#
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# This produces an Ubuntu Core image for testing in file `pc.img.gz`.
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# It will initialize the spread user as well as the project directory
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# (which has to be defined in `PROJECT_PATH`).
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# This is expected to be called from spread.
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# This is to reflash a spread runner.
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# This script takes one argument: a gzipped image to be flashed onto the disk.
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# After successfully running this script, a reboot or power down will
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# flash the machine with the given image.
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set -eux
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DEBIAN_FRONTEND=noninteractive apt install -y --no-install-recommends dracut-core busybox-initramfs
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[ -d /run/initramfs ] || mkdir -p /run/initramfs
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systemd-mount --property=DefaultDependencies=no --options=exec,size=2G none --type=tmpfs /run/initramfs
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cp -T "${1}" /run/initramfs/image.gz
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for try in /usr/lib/systemd/systemd-shutdown /lib/systemd/systemd-shutdown; do
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if [ -x "${try}" ]; then
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systemd_shutdown="${try}"
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fi
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done
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/usr/lib/dracut/dracut-install --ldd -D/run/initramfs -a umount systemctl dd "${systemd_shutdown}"
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/usr/lib/dracut/dracut-install --ldd -D/run/initramfs /usr/lib/initramfs-tools/bin/busybox /bin/busybox
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ln -s busybox /run/initramfs/bin/sh
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ln -s busybox /run/initramfs/bin/gunzip
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if [ -b /dev/vda ]; then
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DISK=/dev/vda
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elif [ -b /dev/sda ]; then
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DISK=/dev/sda
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elif [ -b /dev/nvme0n1 ]; then
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DISK=/dev/nvme0n1
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else
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echo "Cannot find disk" 2>&1
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exit 1
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fi
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cat <<EOF >/run/initramfs/shutdown
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#!/bin/sh
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echo "SHUTTING DOWN"
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set -eu
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umount -l /oldroot
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gunzip -c /image.gz | dd of='${DISK}' bs=32M
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exec '${systemd_shutdown}' "\${@}"
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EOF
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chmod +x /run/initramfs/shutdown
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