====== Ubuntu on Raspberry Pi ======

Notes for configuring Ubuntu 20.04.1 LTS on Raspberry Pi.

===== Custom Ubuntu image =====

I currently use a customized Ubuntu image that includes the following modifications:

  * Disabled resizing of partitions and filesystems to use entire SD card on first boot in cloud-init
  * Disabled automatic patching of Ubuntu on first boot via cloud-init
  * Add users, SSH keys, and sudo configuration for [[:ansible|Ansible]]

===== First boot =====

On first boot you can find the Pi on the network from a DHCP server (or any other host that has an ARP cache for the subnet including this host) using the following:

<code>
#!/bin/bash
echo "The following Raspberry Pi 4 devices have been found:"
arp -a | grep dc:a6
# add MAC for other models...
</code>

==== Grow filesystem and disable cloud-init ====

After logging in you should reconfigure the filesystem and disable cloud-init to ensure that it does not automatically modify the filesytem or partitions in future updates.

<code>
# disable
touch /etc/cloud/cloud-init.disabled

# manually modify the partition table and grow the filesystem
parted /dev/mmcblk0
resizepart # configure partition 2 as desired
quit
resize2fs /dev/mmcblk0p2

# optional: remove cloud-init completely
apt-get purge cloud-init
# if you do not remove cloud-init be sure not to allow your
# configuration to be overwritten in future updates to the package
</code>

Another option is to create a small 1Mb partition after your root partition to ensure that it can never be grown into the empty space on your SD card.

Next do the following:

<code>
# disable the unattended upgrades service (you can re-enable later if you prefer)
systemctl disable unattended-upgrades

# install python for Ansible
apt install python

# set editor to Vim (optional)
update-alternatives --config editor

# set a hostname
echo "$MYHOSTNAME" > /etc/hostname

# don't forget to update /etc/hosts
</code>

Configure network interface for static use:

<code>
# /etc/netplan/99-static.yaml
network:
    version: 2
    renderer: networkd
    ethernets:
        eth0:
            addresses:
                - 10.1.2.3/24
            gateway4: 10.1.2.1
            link-local: [ ]
            nameservers:
                search: [subnet.quay.net, quay.net]
                addresses:
                    - 10.1.2.53
</code>

Test netplan configuration:

<code>
netplan try

# if that works, remove any other config files and run:
netplay apply

# once successfully tested you should also remove the default config from cloud-init
# (add to Ansible playbook in future)
rm -f /etc/netplan/50-cloud-init.yaml
</code>

==== Ansible playbooks ====

<code>
# standard configuration for all Raspberry Pi systems
# this playbook does the following:
#  - base configurations (raspi_ubuntu)
#  - time service config (chrony)
#  - firewall config (nftables)
ansible-playbook -l raspi.in.quay.net raspi_ubuntu.yml

# regenerate SSHD keys on host after build
# NOTE: Ubuntu ships with a default set of SSHD keys
ansible-playbook -l raspi.in.quay.net regen_sshd_keys.yml
</code>

Add the following to Ansible plays in the future:

  * default editor
  * prune packages
  * configre motd
  * apt install lm-sensors

===== Hardware notes =====

Quick reference for Raspberry Pi hardware tools on Ubuntu.

==== Configuring RTC on Ubuntu 20.04 LTS ====

<code>
# Install the I2C tools to access the bus and configure your RTC
apt install i2c-tools

# Enable your RTC in the Pi boot config
RTCMODEL=ds3231
echo "dtoverlay=i2c-rtc,$RTCMODEL" >> /boot/firmware/usercfg.txt 

# show I2C bus config
#  - 68 = hardware detected
#  - UU = dtoverlay configured correctly and driver is loaded
i2cdetect -y 1
</code>

//Reference: [[https://pimylifeup.com/raspberry-pi-rtc/|Raspberry Pi RTC: Adding a Real Time Clock//

===== Reference =====

//See also: [[pi|Raspberry Pi]]//

  * [[https://wiki.ubuntu.com/ARM/RaspberryPi|Ubuntu Wiki: ARM/RaspberryPi]]
  * [[https://elinux.org/RPiconfig|RPiconfig]]
  * [[https://ubuntu.com/download/raspberry-pi|Ubuntu Raspberry Pi Downloads]]
  * [[https://ubuntu.com/tutorials/how-to-install-ubuntu-on-your-raspberry-pi#1-overview|How to install Ubuntu Server on your Raspberry Pi]]
  * [[https://netplan.io/examples/|Netplan configuration examples]]