[pvspain]

I run calibre-server on a headless Linode VM. I am also a paying supporter of this project.

Around 6 months ago, there was a change to the source for calibre-server that introduced a dependency for graphics libraries. This is most unusual for an application designed to run headless.

A possible scenario was the unintentional introduction to the server source of a dependency previously only used in the GUI calibre client which imported a Qt module.

I tried to point this out to Kovid Goyal but was treated quite rudely and given the standard answer of install the graphics libraries. Going down this path led to a situation where the graphics library versions on the calibre build server fell behind the version of the same library on the vanilla Ubuntu 20.04 long term support (LTS) version on Linode VMs. This would only be reconciled by updating dependencies on the calibre build server to LTS versions. I diplomatically pointed this out, but again Kovid Goyal would not investigate.

It is now possible (Calibre 6.21) once again to install calibre-server on vanilla Ubuntu 20.04 LTS on Linode VMs. The requirement for graphics libraries for calibre-server remains in place, and can be resolved by this command:
sudo apt install libopengl0 libglx0 libxcomposite1 libxdamage1 libxrandr2 libxtst6 libxkbfile1

I hope this may help other hapless souls who only want to run calibre headless on Ubuntu.

If this of interest to you, I have developed a systemd daemon for autorestart of calibre server, and nginx pass-through setup enabling SSL server and also client certificates for improved security. I am happy to share the code.