Since I always forget about the timezone settings when spinning up Domino in a container, I just wanted to document it here for my own records. The key here is to provide an environment setting directly when issuing the run command. For me this would be the Central European timezone like so:

docker run -d --name domdev -v /local/notesdata:/local/notesdata --hostname domdev.local --cap-add=SYS_PTRACE -e TZ=Europe/Berlin -p 1352:1352 -p 80:80 -p 443:443 domino-container:12.0.2FP6

This uses the latest 12.0.2 image from HCL, uses a "real" folder on my server's hard disk as a mounted data folder (not a volume), sets the relevant ports and the timezone to Europe/Berlin. That's it folks