No DHCP IP on eth0 with Ubuntu Server 26.04 (64-bit) on Raspberry Pi 4b

This week I was attempting to get up and running with Ubuntu Server 26.04 (64-bit) on a Pi 4b using Raspberry Pi Imager 1.8.5. I noticed this same problem both times I went through this process.

I used the option to edit and apply configuration settings in the Raspberry Pi Imager

General Tab:

• Set hostname

• Set username and password

• unchecked Configure wireless LAN

• set locale settings

Services:

• Enable SSH

• Allow Public Key Authentication Only (and pasted in my public key)

Then I flashed the microSD card, booted the Pi with it, watched a lot of stuff go by and then saw that it was trying and failing to reach the Ubuntu repos to update itself. The eth0 interface link light was on and maybe also flashing activity, but the system was unreachable on the network. Logging in on the console showed no assigned IP to eth0 even though /etc/netplan/50-cloud-init.yaml contained:

network:
  version: 2
  ethernets:
    eth0:
      optional: true
      dhcp4: true

In the end, all I had to do was run sudo netplan apply from the console and it picked up its eth0 IP and other info via DHCP.

Disconnect and power off USB peripheral from the Linux command line

I have a headless Proxmox PVE node that I sometimes need to mount USB storage to. When I'm done with it I can unmount the filesystem on it easily enough with the umount command but then I still have the drive and partitions still connected to the system. (In my case, that looks something like this below with my nvme drives and partitions showing up afterwards.)

root@pm:~# lsblk
NAME                         MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda                            8:0    0   1.9T  0 disk 
└─sda1                         8:1    0   1.9T  0 part

 

In a modern desktop environment on Linux you can find buttons or menu options to 'eject' storage like this but it wasn't obvious to me how to do it from the command line for a USB HDD enclosure. [edit: so the `eject` manual page suggests that running `eject /dev/sda` might have also worked. I'll try it next time!]

So I did a Kagi search and found a solution on Reddit that worked.

From https://www.reddit.com/r/linuxquestions/comments/1dq4ha3/comment/lao9dnq/

Echoing the usb port number to /sys/bus/usb/drivers/usb/unbind works for regular usb devices, like external drives or hubs. It removes them from from the bus and stops them consuming power, just as if they were physically unplugged. You need both the bus number and port, which you can get via lsusb -t. For example if the device is on bus 01 port 3, you would use

echo 1-3 | sudo tee /sys/bus/usb/drivers/usb/unbind

Echoing the same to /sys/bus/usb/drivers/usb/bind plugs it back in.

 

Upgrade self-hosted GitLab instance on Ubuntu after falling too far behind

I recently ran into a signing key issue on an Ubuntu system running gitlab-ee from the official GitLab repos but didn't notice for a while so my normal automatic upgrades hadn't been working to keep it updated. This may have also been affecting other package upgrades... not sure yet.

Anyway, the first thing to solve was getting the latest repo key installed. Downloading and running the script mentioned in step 2 of https://docs.gitlab.com/install/package/ubuntu/?tab=Enterprise+Edition did the trick for the key. 

Afterwards, I was faced with the issue of being multiple Minor revisions behind. This manifested as this error:

Stop optical discs from automatically mounting in Ubuntu 25.10

 I was recently using MakeMKV to rip some old DVDs to watch using Jellyfin/Plex and ran into an issue where the drive seemed to be in contention between GNOME and MakeMKV.

Manually unmounting the DVD in the GNOME dock and restarting MakeMKV seemed to allow it to continue so I had a quick look for how to change that desktop normally useful behaviour while I was working on this task.

 I tried installing dconf-editor but trying to change the org/gnome/desktop/automount value to false gave me a cryptic error about something not being available for editing. Same with other values in that same section. It may have been because I was trying to run it as root rather than my current desktop user or something like that, but since the advice to use that tool was from a decade ago and I'm running Ubuntu 25.10, I had another look around.

I found the gsettings command line utility.

Running gsettings set org.gnome.desktop.media-handling automount false as my logged in user took effect immediately without logging out and in again and I didn't see the MakeMKV problems again.

Afterwards, I ran gsettings set org.gnome.desktop.media-handling automount true to revert to the normally useful default automount behaviour.