Raspberry Pi Headless Bootstrap Script

pi-bootstrap

#!/bin/bash

# pi-bootstrap
#
# Setup an Ubuntu Raspberry Pi image for headless boot.
#
# Copyright Nikolay Botev, MIT License
#

# Default settings
#
DEFAULT_VOLUME=/Volumes/system-boot
DEFAULT_HOSTNAME="ubuntu-$(date +%Y%m%d)"
DEFAULT_WIFI_REGION=US
DEFAULT_SSH_KEY="$HOME/.ssh/id_rsa.pub"

# Gather settings input
#
echo -n "Enter the hostname for the new VM [$DEFAULT_HOSTNAME]: " && read IN_HOSTNAME
HOSTNAME="${IN_HOSTNAME:-$DEFAULT_HOSTNAME}"

echo -n "Enter the name of a Wi-Fi network to connect to [leave blank for no Wi-FI]: " && read WIFI_NAME
if [ -n "$WIFI_NAME" ]; then
  echo -n "Enter the password of Wi-Fi network $WIFI_NAME: " && read WIFI_PASS
  echo -n "Enter the Wi-Fi region [$DEFAULT_WIFI_REGION]: " && read IN_WIFI_REGION
  WIFI_REGION="${IN_WIFI_REGION:-$DEFAULT_WIFI_REGION}"
fi

echo -n "Enter the path of your SSH key file [$DEFAULT_SSH_KEY]: " && read IN_SSH_KEY
SSH_KEY="${IN_SSH_KEY:-$DEFAULT_SSH_KEY}"

echo -n "Enter the boot volume location [$DEFAULT_VOLUME]: " && read IN_VOLUME
VOLUME="${IN_VOLUME:-$DEFAULT_VOLUME}"

# Confirm settings
#
echo
echo "Hostname:          $HOSTNAME"
echo "Wi-Fi Netowrk:     ${WIFI_NAME:-(no wifi)}"
if [ -n "$WIFI_NAME" ]; then
  echo "Wi-Fi Region:      $WIFI_REGION"
fi
echo "SSH Key file:      $SSH_KEY"
echo "Linux Boot Volume: $VOLUME"
echo "Press return to continue."
read

# Execute
#
# - Set hostname
echo "Setting hostname to $HOSTNAME ..."
# https://cloudinit.readthedocs.io/en/latest/topics/modules.html#update-hostname
cat >> "$VOLUME/user-data" <<!

hostname: $HOSTNAME"
!

# - Configure Wi-Fi connection
if [ -n "$WIFI_NAME" ]; then
  echo "Setting up Wi-Fi connection to $WIFI_NAME ..."
  cp "$VOLUME/network-config" "$VOLUME/network-config.orig"
  cat >> "$VOLUME/network-config" <<!
wifis:
  wlan0:
    dhcp4: true
    optional: true
    access-points:
      "$WIFI_NAME":
        password: "$WIFI_PASS"
!

  echo "Setting Wi-Fi region to $WIFI_REGION ..."
  echo "Removing world visibility of Wi-Fi password ..."
  cat >> "$VOLUME/user-data" <<!

runcmd:
- [ sed, -i, -e, s/REGDOMAIN=.*/REGDOMAIN=US/, /etc/default/crda ]
- [ iw, reg, set, US ]
- [ mv, /boot/firmware/network-config.orig, /boot/firmware/network-config ]
- [ chmod, -R, go-rwx, /etc/netplan/ ]
!
fi

# - Enable mDNS (aka Bonjour / Zeroconf)
echo "Setting up avahi-daemon ..."
cat >> "$VOLUME/user-data" <<!

package_update: true
package_upgrade: true
packages:
- avahi-daemon
!

# - Configure user SSH key login
# https://askubuntu.com/questions/1302840/ubuntu-setup-user-data-ssh
# https://g.masse.me/blog/2020/01/14/HOW-TO-pre-configure-your-Ubuntu-installation-for-a-Raspberry-Pi/
echo "Adding user SSH key ..."
cat >> "$VOLUME/user-data" <<!

system_info:
  default_user:
    ssh_authorized_keys:
      - $(cat "$SSH_KEY")
    sudo: ALL=(ALL) NOPASSWD:ALL
!

echo "Disabling SSH password auth ..."
sed -i.bak -e "s/ssh_pwauth: true/ssh_pwauth: false/" "$VOLUME/user-data"
rm "$VOLUME/user-data.bak"

echo "All done."