scripts: Add a script to bootstrap NixOS on Linode.com

scripts/linode-bootstrap.sh

@@ -0,0 +1,154 @@
+#!/bin/sh
+
+################################################################################
+#
+# Bootstrap NixOS on Linode.
+#
+# Based on (read this so you know what's going on):
+#
+#   https://gist.github.com/nocoolnametom/a359624afce4278f16e2760fe65468ccd
+#
+# Prerequisites:
+#
+#   1. Create three (3) disk images:
+#
+#      - Installer: 650MB (or big enough for the NixOS ISO)
+#      - Swap: 256MB (Linode recommendation)
+#      - NixOS: >= 4GB
+#
+#   2. Boot from the Rescue page with disks set up like:
+#
+#      - /dev/sda -> Installer Disk
+#      - /dev/sdb -> Swap Disk
+#      - /dev/sdc -> NixOS Disk
+#
+#      NOTE: This is the default setting but it's different than the
+#      instructions from nocoolnametom.
+#
+#   3. When you are booted into Finnix (step 2) pipe this script to sh:
+#
+#          curl -k <url> | sh
+#
+#      The machine will stop running after NixOS was written to the
+#      installer disk.
+#
+#   4. Create a new configuration profile for installing NixOS:
+#
+#        - Kernel: Direct
+#        - /dev/sda -> Installer Disk
+#        - /dev/sdb -> Swap
+#        - /dev/sdc -> NixOS
+#        - Filesystem/Boot Helpers: All off
+#
+#      NOTE: Disk order is unimportant here, except that the installer
+#      disk should be on /dev/sda.
+#
+#   5. Reboot into the installer profile.
+#
+#      NOTE: You'll need to quickly press TAB when the Grub menu
+#      appears and enter the following before pressing ENTER:
+#
+#          console=ttyS0
+#
+#   6. Run this script again, just like in step 3.
+#
+#   7. Create the final configuration for your new server and boot
+#      into NixOS (more details can be found in the guide referenced
+#      above).
+
+################################################################################
+set -e
+set -u
+set -x
+
+################################################################################
+# FIXME: Calculate this URL at run time:
+NIXOS_URL="https://d3g5gsiof5omrk.cloudfront.net/nixos/18.09/nixos-18.09.1834.9d608a6f592/nixos-minimal-18.09.1834.9d608a6f592-x86_64-linux.iso"
+
+################################################################################
+# Label the disks so the rest of the script only uses labels.
+label_disks() {
+  e2label /dev/sda installer
+  e2label /dev/sdc nixos
+  swaplabel -L swap /dev/sdb
+}
+
+################################################################################
+# Download the NixOS ISO and write it to the installer disk.
+write_installer_to_disk() {
+  curl -k "$NIXOS_URL" \
+    | dd bs=1M of=/dev/disk/by-label/installer
+
+  sync
+}
+
+################################################################################
+# Prepare NixOS disk and swap disk:
+prep_nixos_disks() {
+  mount /dev/disk/by-label/nixos /mnt
+  swapon /dev/disk/by-label/swap
+}
+
+################################################################################
+# Given a disk label, update the hardware configuration so the UUID is
+# replaced with a disk lable.
+hardware_uuid_to_label() {
+  label=$1
+  uuid=$(blkid --match-tag UUID --output value /dev/disk/by-label/"$label")
+
+  sed -i \
+      -e "s|/dev/disk/by-uuid/$uuid|/dev/disk/by-label/$label|" \
+      /mnt/etc/nixos/hardware-configuration.nix
+}
+
+################################################################################
+# Update configuration.nix with recommended Grub settings:
+update_grub_settings() {
+  # Remove all current grub lines:
+  sed -i \
+      -e '/boot\.loader\.grub/d' \
+      -e '/boot\.kernelParams/d' \
+      -e '/^}$/d' \
+      /mnt/etc/nixos/configuration.nix
+
+  cat >> /mnt/etc/nixos/configuration.nix <<EOF
+  boot.loader.grub.enable = true;
+  boot.loader.grub.version = 2;
+  boot.loader.grub.device = "nodev";
+  boot.loader.grub.copyKernels = true;
+  boot.loader.grub.fsIdentifier = "label";
+  boot.loader.grub.extraConfig = "serial; terminal_input serial; terminal_output serial";
+  boot.kernelParams = [ "console=ttyS0" ];
+}
+EOF
+}
+
+################################################################################
+# Enable SSH and allow root to login (So you can use NixOps later).
+enable_ssh() {
+  # Remove the closing curly:
+  sed -i -e '/^}$/d' /mnt/etc/nixos/configuration.nix
+
+  cat >> /mnt/etc/nixos/configuration.nix <<EOF
+  services.openssh.enable = true;
+  services.openssh.permitRootLogin = "yes";
+  services.openssh.openFirewall = true;
+}
+EOF
+}
+
+################################################################################
+if [ "$(hostname)" = "finnix" ]; then
+  label_disks
+  write_installer_to_disk
+  halt
+else
+  prep_nixos_disks
+  nixos-generate-config --root /mnt
+  hardware_uuid_to_label nixos
+  hardware_uuid_to_label swap
+  update_grub_settings
+  enable_ssh
+  nixos-install
+  shutdown now
+fi