Kevin Veen-Birkenbach f79bac2927 Release version 1.0.0
2026-05-12 23:38:38 +02:00
2026-05-12 17:03:59 +02:00
2026-05-12 17:03:59 +02:00
2026-05-12 17:03:59 +02:00
2026-05-12 23:38:38 +02:00
2026-05-12 17:03:59 +02:00
2026-05-12 23:38:38 +02:00
2026-05-12 23:38:38 +02:00

Arch Linux with LUKS and btrfs on a Hetzner server

A small Python CLI (hal) that wraps every step of installing, encrypting, and maintaining an Arch Linux server on Hetzner Dedicated hardware with software RAID, LUKS full-disk encryption, btrfs on top of LVM, and remote unlock via dropbear in the initramfs.

Author: Kevin Veen-Birkenbach <kevin@veen.world> — veen.world
License: MIT — see LICENSE

Install the CLI

make install   # → pip install --user -e .
hal --help

After install, every step below is a single hal subcommand.

Subcommand reference

Run hal --help, hal <group> --help, or hal <group> <target> --help for the live reference.

Top-level

Command What it does
hal status <host> Ping + port scan + SSH banner. No login.
hal diagnose <host> Rescue → chroot, runs a fixed inspection script. Pipe with tee to save.
hal unlock <host> Send the LUKS passphrase from the keyring to dropbear (cryptroot-unlock).
hal forget <host> Clear the cached LUKS passphrase from libsecret.

hal connect <target> <host> [cmd]

Open a shell, or run cmd non-interactively.

Target Where it goes
rescue Hetzner Rescue OS
server Booted Arch system
chroot Rescue → chroot of installed Arch (LUKS-unlocks + mounts first)

hal setup <target> <host> — one-time install operations

Target What it does
image --autosetup PATH In rescue: upload autosetup, run installimage. Destructive.
dropbear Booted Arch: install dropbear + mkinitcpio plugins, copy authorized_keys, patch HOOKS.
grub Rescue → chroot: install grub package, write LUKS-aware /etc/default/grub, grub-install on every boot disk.
encrypt-root Rescue: LUKS-encrypt /dev/md1, preserve data via /oldroot copy. Destructive on /dev/md1. Confirms before format.

hal fix <target> <host> — recovery + maintenance operations

Target What it does
boot Patch PermitRootLogin, enable persistent journald.
network Rewrite .network files to match by MACAddress= instead of interface name.
grub Refresh Stage1 + core.img in MBR (Arch doesn't do this automatically after grub upgrades).
kernel Roll the linux package back to the previous version (cache or archive.archlinux.org).
static-ip Replace ip=dhcp in /etc/default/grub with a static cmdline IP derived from /etc/systemd/network/*.network.
upgrade Full pacman -Syyu + initramfs rebuild + grub-install on every boot disk.
expand-fs On booted Arch: lvresize -l +100%FREE /dev/vg0/root && btrfs filesystem resize max /.

The LUKS passphrase is prompted (hidden) on first use and cached in the libsecret keyring per host — subsequent runs against the same host don't prompt.

Setup flow

Each section is a small handful of hal commands. Click into the corresponding table row above for what each one actually does.

Set the server IP/hostname once per shell — every block below uses $SERVER:

export SERVER=your_server_ip   # e.g. 46.4.224.77 or boot.echoserver

1. Install Arch via installimage

hal connect rescue "$SERVER"                              # verify rescue is up
hal setup image "$SERVER" --autosetup autosetup           # see autosetup.example
hal connect rescue "$SERVER" reboot

Tip: copy autosetup.example to autosetup, edit DRIVE1/DRIVE2/HOSTNAME, then run setup image.

2. Boot Arch, install the dropbear stack

hal connect server "$SERVER"                              # verify SSH works
hal connect server "$SERVER" pacman -Syyu                 # bring system current
hal setup dropbear "$SERVER"                              # dropbear + mkinitcpio plugins + HOOKS

3. Convert root to LUKS

Activate Rescue in the Hetzner Robot UI, then:

hal connect server "$SERVER" reboot                       # boots back into rescue
hal connect rescue "$SERVER"                              # verify rescue is up
hal setup encrypt-root "$SERVER"                          # LUKS conversion — DESTRUCTIVE
hal setup grub "$SERVER"                                  # initial GRUB for LUKS boot
hal fix static-ip "$SERVER"                               # static initramfs IP — Hetzner DHCP is fragile

Deactivate Rescue in the Hetzner Robot UI, then:

hal connect rescue "$SERVER" reboot                       # final reboot into encrypted system

4. Day-to-day use

After every reboot the system blocks at dropbear in initramfs waiting for the LUKS passphrase. From your client:

hal status "$SERVER"                                      # wait for dropbear / sshd
hal unlock "$SERVER"                                      # send passphrase to dropbear
hal connect server "$SERVER"                              # normal SSH after unlock

5. Expand the root filesystem later

If the autosetup gave you a small root LV and the rest is free LVM space:

hal fix expand-fs "$SERVER"

Debugging an unresponsive server

The server isn't booting / SSH never comes up:

# 1. Reach the server's chroot
hal connect rescue "$SERVER"                              # via Hetzner Robot → Rescue first
hal diagnose "$SERVER" | tee "diag-$(date +%F-%H%M).log"

# 2. Apply best-guess fixes in roughly this order
hal fix boot "$SERVER"                                    # sshd config + journald
hal fix network "$SERVER"                                 # interface naming drift
hal fix grub "$SERVER"                                    # stale MBR after grub upgrades
hal fix static-ip "$SERVER"                               # DHCP-in-initramfs fragility

# 3. Last-resort kernel rollback (if a kernel bump is the suspect)
hal fix kernel "$SERVER"

# 4. Or, after fixing whatever was broken, upgrade everything cleanly
hal fix upgrade "$SERVER"

Every hal chroot command makes its own backups (<file>.hal-backup) before mutating anything, so individual fixes can be reverted by hand.

Sources

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