## Switch oracle-cloud-instances to Debian

## Debootstrap debian on arm64

Original credits for this page:

• https://sj14.gitlab.io/post/2021/01-30-free-k8s-cloud-cluster/
• https://serverfault.com/questions/528075/is-it-possible-to-on-line-shrink-a-ext4-volume-with-lvm

# Resize rootfs without LVM

1. Create a ubuntu-instance ( Canonical Ubuntu 24.04 Minimal aarch64 )
2. Connect to the node, using ubuntu as the username, become root.
3. Add the following files, make them executable, and rebuild initramfs.

/etc/initramfs-tools/hooks/resizefs

#!/bin/sh

set -e

PREREQS=""

prereqs() { echo "$PREREQS"; }

case $1 in
    prereqs)
        prereqs
        exit 0
    ;;
esac

. /usr/share/initramfs-tools/hook-functions

copy_exec /sbin/e2fsck
copy_exec /sbin/resize2fs

exit 0

/etc/initramfs-tools/scripts/local-premount/resizefs

#!/bin/sh

set -e

PREREQS=""

prereqs() { echo "$PREREQS"; }

case "$1" in
    prereqs)
        prereqs
        exit 0
    ;;
esac

# simple device example
/sbin/e2fsck -yf /dev/sda1
/sbin/resize2fs /dev/sda1 6G
/sbin/e2fsck -yf /dev/sda1

chmod +x /etc/initramfs-tools/hooks/resizefs /etc/initramfs-tools/scripts/local-premount/resizefs

update-initramfs -u && update-grub

4. Remove growpart and resizefs from /etc/cloud/cloud.cfg, and reboot.

   Filesystem      Size  Used Avail Use% Mounted on
   /dev/sda1       5.8G  1.8G  4.0G  32% /
   

5. Run cfdisk /dev/sda and resize sda1 as a partition with 10GB, resize rootfs with resize2fs /dev/sda1.
6. Verify that you have a smaller rootfs.

## Debootstrap debian

1. apt update && apt install debootstrap -y
2. cfdisk /dev/sda, create a new 6gb partition
3. pvcreate /dev/sda2 && vgcreate base /dev/sda2 && lvcreate -L5G base –name root
4. mkfs.ext4 /dev/mapper/base-root -L root -m0 && mount /dev/mapper/base-root /mnt/
5. debootstrap trixie /mnt http://deb.debian.org/debian
6. mount –bind /dev /mnt/dev; mount –bind /sys /mnt/sys; mount –bind /proc /mnt/proc; cp /etc/fstab /mnt/etc/fstab

mkdir -p /mnt/root/.ssh
chmod 0700 /mnt/root/.ssh
cp /home/ubuntu/.ssh/authorized_keys /mnt/root/.ssh/authorized_keys
chmod 0600 /mnt/root/.ssh/authorized_keys

8. chroot /mnt
9. apt install ssh sudo python3-simplejson lvm2 -y
10. sed ’s/cloudimg-rootfs/root/g’ -i /etc/fstab

echo 'auto enp0s6' > /etc/network/interfaces.d/repair
echo 'iface enp0s6 inet dhcp' >> /etc/network/interfaces.d/repair
systemctl enable systemd-networkd

12. mkdir /boot/efi && mount -a
13. apt install grub-efi-arm64 linux-image-arm64 -y
14. grub-install /dev/sda && update-grub
15. exit
16. reboot
17. delete ssh-key, and re-connect as root
18. pvcreate /dev/sda1
19. vgextend base /dev/sda1 && pvmove -n root /dev/sda2 /dev/sda1
20. vgreduce base /dev/sda2 && pvremove /dev/sda2
21. fdisk /dev/sda, delete sda2, resize sda1 to 20G
22. reboot
23. pvresize /dev/sda1 && lvresize -r -L20G /dev/base/root